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201. Precise near-infrared photometry, accounting for precipitable water vapour at SPECULOOS Southern Observatory.

Author

Pedersen, Peter P, Murray, C A, Queloz, D, Gillon, M, Demory, B O, Triaud, A H M J, de Wit, J, Delrez, L, Dransfield, G, Ducrot, E, Garcia, L J, Gómez Maqueo Chew, Y, Günther, M N, Jehin, E, McCormac, J, Niraula, P, Pozuelos, F J, Rackham, B V, Schanche, N, and Sebastian, D

Subjects
PRECIPITABLE water, WATER vapor, PHOTOMETRY, OBSERVATORIES, LIGHT curves
Abstract

The variability induced by precipitable water vapour (PWV) can heavily affect the accuracy of time-series photometric measurements gathered from the ground, especially in the near-infrared. We present here a novel method of modelling and mitigating this variability, as well as open-sourcing the developed tool – Umbrella. In this study, we evaluate the extent to which the photometry in three common bandpasses (r ′, i ′, z ′), and SPECULOOS' primary bandpass (I + z ′), are photometrically affected by PWV variability. In this selection of bandpasses, the I + z ′ bandpass was found to be most sensitive to PWV variability, followed by z ′, i ′, and r ′. The correction was evaluated on global light curves of nearby late M- and L-type stars observed by SPECULOOS' Southern Observatory (SSO) with the I + z ′ bandpass, using PWV measurements from the LHATPRO and local temperature/humidity sensors. A median reduction in RMS of 1.1 per cent was observed for variability shorter than the expected transit duration for SSO's targets. On timescales longer than the expected transit duration, where long-term variability may be induced, a median reduction in RMS of 53.8 per cent was observed for the same method of correction. [ABSTRACT FROM AUTHOR]

Published
2023
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202. CHEOPS observations of the HD 108236 planetary system: A fifth planet, improved ephemerides, and planetary radii

Author

Bonfanti, A, Delrez, L, Hooton, MJ, Wilson, TG, Fossati, L, Alibert, Y, Hoyer, S, Mustill, AJ, Osborn, HP, Adibekyan, V, Gandolfi, D, Salmon, S, Sousa, SG, Tuson, A, Van Grootel, V, Cabrera, J, Nascimbeni, V, Maxted, PFL, Barros, SCC, Billot, N, Bonfils, X, Borsato, L, Broeg, C, Davies, MB, Deleuil, M, Demangeon, ODS, Fridlund, M, Lacedelli, G, Lendl, M, Persson, C, Santos, NC, Scandariato, G, Szabó, GM, Collier Cameron, A, Udry, S, Benz, W, Beck, M, Ehrenreich, D, Fortier, A, Isaak, KG, Queloz, D, Alonso, R, Asquier, J, Bandy, T, Bárczy, T, Barrado, D, Barragán, O, Baumjohann, W, Beck, T, Bekkelien, A, Bergomi, M, Brandeker, A, Busch, MD, Cessa, V, Charnoz, S, Chazelas, B, Corral Van Damme, C, Demory, BO, Erikson, A, Farinato, J, Futyan, D, Garcia Muñoz, A, Gillon, M, Guedel, M, Guterman, P, Hasiba, J, Heng, K, Hernandez, E, Kiss, L, Kuntzer, T, Laskar, J, Lecavelier Des Etangs, A, Lovis, C, Magrin, D, Malvasio, L, Marafatto, L, Michaelis, H, Munari, M, Olofsson, G, Ottacher, H, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piazza, D, Piotto, G, Pollacco, D, Ragazzoni, R, Rando, N, Ratti, F, Rauer, H, Ribas, I, Rieder, M, Rohlfs, R, Safa, F, Salatti, M, Ségransan, D, Simon, AE, Smith, AMS, Sordet, M, Hooton, Matthew John [0000-0003-0030-332X], Queloz, Didier [0000-0002-3012-0316], and Apollo - University of Cambridge Repository

Subjects
planets and satellites: detection, stars: fundamental parameters, ephemerides, planets and satellites: fundamental parameters
Abstract

The detection of a super-Earth and three mini-Neptunes transiting the bright ($V$ = 9.2 mag) star HD 108236 (also known as TOI-1233) was recently reported on the basis of TESS and ground-based light curves. We perform a first characterisation of the HD 108236 planetary system through high-precision CHEOPS photometry and improve the transit ephemerides and system parameters. We characterise the host star through spectroscopic analysis and derive the radius with the infrared flux method. We constrain the stellar mass and age by combining the results obtained from two sets of stellar evolutionary tracks. We analyse the available TESS light curves and one CHEOPS transit light curve for each known planet in the system. We find that HD 108236 is a Sun-like star with $R_{\star}=0.877\pm0.008 R_{\odot}$, $M_{\star}=0.869^{+0.050}_{-0.048} M_{\odot}$, and an age of $6.7_{-5.1}^{+4.0}$ Gyr. We report the serendipitous detection of an additional planet, HD 108236 f, in one of the CHEOPS light curves. For this planet, the combined analysis of the TESS and CHEOPS light curves leads to a tentative orbital period of about 29.5 days. From the light curve analysis, we obtain radii of $1.615\pm0.051$, $2.071\pm0.052$, $2.539_{-0.065}^{+0.062}$, $3.083\pm0.052$, and $2.017_{-0.057}^{+0.052}$ $R_{\oplus}$ for planets HD 108236 b to HD 108236 f, respectively. These values are in agreement with previous TESS-based estimates, but with an improved precision of about a factor of two. We perform a stability analysis of the system, concluding that the planetary orbits most likely have eccentricities smaller than 0.1. We also employ a planetary atmospheric evolution framework to constrain the masses of the five planets, concluding that HD 108236 b and HD 108236 c should have an Earth-like density, while the outer planets should host a low mean molecular weight envelope.

Published
2021
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203. The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS

Author

Lendl, M, Csizmadia, S, Deline, A, Fossati, L, Kitzmann, D, Heng, K, Hoyer, S, Salmon, S, Benz, W, Broeg, C, Ehrenreich, D, Fortier, A, Queloz, D, Bonfanti, A, Brandeker, A, Collier Cameron, A, Delrez, L, Garcia Muñoz, A, Hooton, MJ, Maxted, PFL, Morris, BM, Van Grootel, V, Wilson, TG, Alibert, Y, Alonso, R, Asquier, J, Bandy, T, Bárczy, T, Barrado, D, Barros, SCC, Baumjohann, W, Beck, M, Beck, T, Bekkelien, A, Bergomi, M, Billot, N, Biondi, F, Bonfils, X, Bourrier, V, Busch, MD, Cabrera, J, Cessa, V, Charnoz, S, Chazelas, B, Corral Van Damme, C, Davies, MB, Deleuil, M, Demangeon, ODS, Demory, BO, Erikson, A, Farinato, J, Fridlund, M, Futyan, D, Gandolfi, D, Gillon, M, Guterman, P, Hasiba, J, Hernandez, E, Isaak, KG, Kiss, L, Kuntzer, T, Lecavelier Des Etangs, A, Lüftinger, T, Laskar, J, Lovis, C, Magrin, D, Malvasio, L, Marafatto, L, Michaelis, H, Munari, M, Nascimbeni, V, Olofsson, G, Ottacher, H, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piazza, D, Piotto, G, Pollacco, D, Ratti, F, Rauer, H, Ragazzoni, R, Rando, N, Ribas, I, Rieder, M, Rohlfs, R, Safa, F, Santos, NC, Scandariato, G, Ségransan, D, Simon, AE, Singh, V, Smith, AMS, Sordet, M, Sousa, SG, Steller, M, Szabó, GM, Thomas, N, Tschentscher, M, Queloz, Didier [0000-0002-3012-0316], Hooton, Matthew John [0000-0003-0030-332X], and Apollo - University of Cambridge Repository

Subjects
planets and satellites: atmospheres, techniques: photometric, planets and satellites: individual: WASP-189 b
Abstract

The CHEOPS space mission dedicated to exoplanet follow-up was launched in December 2019, equipped with the capacity to perform photometric measurements at the 20 ppm level. As CHEOPS carries out its observations in a broad optical passband, it can provide insights into the reflected light from exoplanets and constrain the short-wavelength thermal emission for the hottest of planets by observing occultations and phase curves. Here, we report the first CHEOPS observation of an occultation, namely, that of the hot Jupiter WASP-189b, a $M_P \approx 2 M_J$ planet orbiting an A-type star. We detected the occultation of WASP-189 b at high significance in individual measurements and derived an occultation depth of $dF = 87.9 \pm 4.3$ppm based on four occultations. We compared these measurements to model predictions and we find that they are consistent with an unreflective atmosphere heated to a temperature of $3435 \pm 27$K, when assuming inefficient heat redistribution. Furthermore, we present two transits of WASP-189b observed by CHEOPS. These transits have an asymmetric shape that we attribute to gravity darkening of the host star caused by its high rotation rate. We used these measurements to refine the planetary parameters, finding a $\sim25\%$ deeper transit compared to the discovery paper and updating the radius of WASP-189b to $1.619\pm0.021 R_J$. We further measured the projected orbital obliquity to be $\lambda = 86.4^{+2.9}_{-4.4}$deg, a value that is in good agreement with a previous measurement from spectroscopic observations, and derived a true obliquity of $\Psi = 85.4\pm4.3$deg. Finally, we provide reference values for the photometric precision attained by the CHEOPS satellite: for the V=6.6 mag star, and using a one-hour binning, we obtain a residual RMS between 10 and 17ppm on the individual light curves, and 5.7ppm when combining the four visits.

Published
2021
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204. The CHEOPS mission

Author

Benz, W, Broeg, C, Fortier, A, Rando, N, Beck, T, Beck, M, Queloz, D, Ehrenreich, D, Maxted, PFL, Isaak, KG, Billot, N, Alibert, Y, Alonso, R, António, C, Asquier, J, Bandy, T, Bárczy, T, Barrado, D, Barros, SCC, Baumjohann, W, Bekkelien, A, Bergomi, M, Biondi, F, Bonfils, X, Borsato, L, Brandeker, A, Busch, MD, Cabrera, J, Cessa, V, Charnoz, S, Chazelas, B, Collier Cameron, A, Corral Van Damme, C, Cortes, D, Davies, MB, Deleuil, M, Deline, A, Delrez, L, Demangeon, O, Demory, BO, Erikson, A, Farinato, J, Fossati, L, Fridlund, M, Futyan, D, Gandolfi, D, Garcia Munoz, A, Gillon, M, Guterman, P, Gutierrez, A, Hasiba, J, Heng, K, Hernandez, E, Hoyer, S, Kiss, LL, Kovacs, Z, Kuntzer, T, Laskar, J, Lecavelier Des Etangs, A, Lendl, M, López, A, Lora, I, Lovis, C, Lüftinger, T, Magrin, D, Malvasio, L, Marafatto, L, Michaelis, H, De Miguel, D, Modrego, D, Munari, M, Nascimbeni, V, Olofsson, G, Ottacher, H, Ottensamer, R, Pagano, I, Palacios, R, Pallé, E, Peter, G, Piazza, D, Piotto, G, Pizarro, A, Pollaco, D, Ragazzoni, R, Ratti, F, Rauer, H, Ribas, I, Rieder, M, Rohlfs, R, Safa, F, Salatti, M, Santos, NC, Scandariato, G, Ségransan, D, Simon, AE, Smith, AMS, Sordet, M, Sousa, SG, Steller, M, Szabó, GM, Benz, W [0000-0001-7896-6479], and Apollo - University of Cambridge Repository

Subjects
High-precision transit photometry, Exoplanets, Physics::Space Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, CHEOPS, Small mission, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The CHaracterising ExOPlanet Satellite (CHEOPS) was selected in 2012, as the first small mission in the ESA Science Programme and successfully launched in December 2019. CHEOPS is a partnership between ESA and Switzerland with important contributions by ten additional ESA Member States. CHEOPS is the first mission dedicated to search for transits of exoplanets using ultrahigh precision photometry on bright stars already known to host planets. As a follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible, existing radii measurements or provide first accurate measurements for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys and to following phase curves. CHEOPS will provide prime targets for future spectroscopic atmospheric characterisation. Requirements on the photometric precision and stability have been derived for stars with magnitudes ranging from 6 to 12 in the V band. In particular, CHEOPS shall be able to detect Earth-size planets transiting G5 dwarf stars in the magnitude range between 6 and 9 by achieving a photometric precision of 20 ppm in 6 hours of integration. For K stars in the magnitude range between 9 and 12, CHEOPS shall be able to detect transiting Neptune-size planets achieving a photometric precision of 85 ppm in 3 hours of integration. This is achieved by using a single, frame-transfer, back-illuminated CCD detector at the focal plane assembly of a 33.5 cm diameter telescope. The 280 kg spacecraft has a pointing accuracy of about 1 arcsec rms and orbits on a sun-synchronous dusk-dawn orbit at 700 km altitude. The nominal mission lifetime is 3.5 years. During this period, 20% of the observing time is available to the community through a yearly call and a discretionary time programme managed by ESA.

Published
2021
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205. Six transiting planets and a chain of Laplace resonances in TOI-178

Author

Leleu, A, Alibert, Y, Hara, NC, Hooton, MJ, Wilson, TG, Robutel, P, Delisle, JB, Laskar, J, Hoyer, S, Lovis, C, Bryant, EM, Ducrot, E, Cabrera, J, Delrez, L, Acton, JS, Adibekyan, V, Allart, R, Allende Prieto, C, Alonso, R, Alves, D, Anderson, DR, Angerhausen, D, Anglada Escude´, G, Asquier, J, Barrado, D, Barros, SCC, Baumjohann, W, Bayliss, D, Beck, M, Beck, T, Bekkelien, A, Benz, W, Billot, N, Bonfanti, A, Bonfils, X, Bouchy, F, Bourrier, V, Boueundefined, G, Brandeker, A, Broeg, C, Buder, M, Burdanov, A, Burleigh, MR, Baundefinedrczy, T, Cameron, AC, Chamberlain, S, Charnoz, S, Cooke, BF, Corral Van Damme, C, Correia, ACM, Cristiani, S, Damasso, M, Davies, MB, Deleuil, M, Demangeon, ODS, Demory, BO, Di Marcantonio, P, Di Persio, G, Dumusque, X, Ehrenreich, D, Erikson, A, Figueira, P, Fortier, A, Fossati, L, Fridlund, M, Futyan, D, Gandolfi, D, Garciaundefined Munoundefinedz, A, Garcia, LJ, Gill, S, Gillen, E, Gillon, M, Goad, MR, Gonzaundefinedlez Hernaundefinedndez, JI, Guedel, M, Guundefinednther, MN, Haldemann, J, Henderson, B, Heng, K, Hogan, AE, Isaak, K, Jehin, E, Jenkins, JS, Jordaundefinedn, A, Kiss, L, Kristiansen, MH, Lam, K, Lavie, B, Lecavelier Des Etangs, A, Lendl, M, Lillo-Box, J, Lo Curto, G, Magrin, D, Martins, CJAP, Maxted, PFL, McCormac, J, Mehner, A, Micela, G, Molaro, P, Moyano, M, Hooton, Matthew John [0000-0003-0030-332X], and Apollo - University of Cambridge Repository

Subjects
techniques: photometric, planets and satellites: detection, planets and satellites: dynamical evolution and stability, Astrophysics::Earth and Planetary Astrophysics, celestial mechanics, techniques: spectroscopic
Abstract

Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at a 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152(-0.070/+0.073) to 2.87(-0.13/+0.14) Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02(+0.28/-0.23) to 0.177(+0.055/-0.061) times the Earth's density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.

Published
2021
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206. Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops

Author

Maxted, P F L, primary, Ehrenreich, D, additional, Wilson, T G, additional, Alibert, Y, additional, Cameron, A Collier, additional, Hoyer, S, additional, Sousa, S G, additional, Olofsson, G, additional, Bekkelien, A, additional, Deline, A, additional, Delrez, L, additional, Bonfanti, A, additional, Borsato, L, additional, Alonso, R, additional, Anglada Escudé, G, additional, Barrado, D, additional, Barros, S C C, additional, Baumjohann, W, additional, Beck, M, additional, Beck, T, additional, Benz, W, additional, Billot, N, additional, Biondi, F, additional, Bonfils, X, additional, Brandeker, A, additional, Broeg, C, additional, Bárczy, T, additional, Cabrera, J, additional, Charnoz, S, additional, Corral Van Damme, C, additional, Csizmadia, Sz, additional, Davies, M B, additional, Deleuil, M, additional, Demangeon, O D S, additional, Demory, B-O, additional, Erikson, A, additional, Florén, H G, additional, Fortier, A, additional, Fossati, L, additional, Fridlund, M, additional, Futyan, D, additional, Gandolfi, D, additional, Gillon, M, additional, Guedel, M, additional, Guterman, P, additional, Heng, K, additional, Isaak, K G, additional, Kiss, L, additional, Laskar, J, additional, Lecavelier des Etangs, A, additional, Lendl, M, additional, Lovis, C, additional, Magrin, D, additional, Nascimbeni, V, additional, Ottensamer, R, additional, Pagano, I, additional, Pallé, E, additional, Peter, G, additional, Piotto, G, additional, Pollacco, D, additional, Pozuelos, F J, additional, Queloz, D, additional, Ragazzoni, R, additional, Rando, N, additional, Rauer, H, additional, Reimers, C, additional, Ribas, I, additional, Salmon, S, additional, Santos, N C, additional, Scandariato, G, additional, Simon, A E, additional, Smith, A M S, additional, Steller, M, additional, Swayne, M I, additional, Szabó, Gy M, additional, Ségransan, D, additional, Thomas, N, additional, Udry, S, additional, Van Grootel, V, additional, and Walton, N A, additional

Published
2021
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207. The changing face of AU Mic b: stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS

Author

Szabó, Gy. M., primary, Gandolfi, D., additional, Brandeker, A., additional, Csizmadia, Sz., additional, Garai, Z., additional, Billot, N., additional, Broeg, C., additional, Ehrenreich, D., additional, Fortier, A., additional, Fossati, L., additional, Hoyer, S., additional, Kiss, L., additional, des Etangs, A. Lecavelier, additional, Maxted, P. F. L., additional, Ribas, I., additional, Alibert, Y., additional, Alonso, R., additional, Anglada Escudé, G., additional, Bárczy, T., additional, Barros, S. C. C., additional, Barrado, D., additional, Baumjohann, W., additional, Beck, M., additional, Beck, T., additional, Bekkelien, A., additional, Bonfils, X., additional, Benz, W., additional, Borsato, L., additional, Busch, M-D., additional, Cabrera, J., additional, Charnoz, S., additional, Collier Cameron, A., additional, Van Damme, C. Corral, additional, Davies, M. B., additional, Delrez, L., additional, Deleuil, M., additional, Demangeon, O. D. S., additional, Demory, B.-O., additional, Erikson, A., additional, Fridlund, M., additional, Futyan, D., additional, García Muñoz, A., additional, Gillon, M., additional, Guedel, M., additional, Guterman, P., additional, Heng, K., additional, Isaak, K. G., additional, Lacedelli, G., additional, Laskar, J., additional, Lendl, M., additional, Lovis, C., additional, Luntzer, A., additional, Magrin, D., additional, Nascimbeni, V., additional, Olofsson, G., additional, Osborn, H. P., additional, Ottensamer, R., additional, Pagano, I., additional, Pallé, E., additional, Peter, G., additional, Piazza, D., additional, Piotto, G., additional, Pollacco, D., additional, Queloz, D., additional, Ragazzoni, R., additional, Rando, N., additional, Rauer, H., additional, Santos, N. C., additional, Scandariato, G., additional, Ségransan, D., additional, Serrano, L. M., additional, Sicilia, D., additional, Simon, A. E., additional, Smith, A. M. S., additional, Sousa, S. G., additional, Steller, M., additional, Thomas, N., additional, Udry, S., additional, Van Grootel, V., additional, Walton, N. A., additional, and Wilson, T. G., additional

Published
2021
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208. CHEOPS precision phase curve of the Super-Earth 55 Cancri e

Author

Morris, B. M., primary, Delrez, L., additional, Brandeker, A., additional, Cameron, A. C., additional, Simon, A. E., additional, Futyan, D., additional, Olofsson, G., additional, Hoyer, S., additional, Fortier, A., additional, Demory, B.-O., additional, Lendl, M., additional, Wilson, T. G., additional, Oshagh, M., additional, Heng, K., additional, Ehrenreich, D., additional, Sulis, S., additional, Alibert, Y., additional, Alonso, R., additional, Anglada Escudé, G., additional, Barrado, D., additional, Barros, S. C. C., additional, Baumjohann, W., additional, Beck, M., additional, Beck, T., additional, Bekkelien, A., additional, Benz, W., additional, Bergomi, M., additional, Billot, N., additional, Bonfils, X., additional, Bourrier, V., additional, Broeg, C., additional, Bárczy, T., additional, Cabrera, J., additional, Charnoz, S., additional, Davies, M. B., additional, De Miguel Ferreras, D., additional, Deleuil, M., additional, Deline, A., additional, Demangeon, O. D. S., additional, Erikson, A., additional, Floren, H. G., additional, Fossati, L., additional, Fridlund, M., additional, Gandolfi, D., additional, García Muñoz, A., additional, Gillon, M., additional, Guedel, M., additional, Guterman, P., additional, Isaak, K., additional, Kiss, L., additional, Laskar, J., additional, Lecavelier des Etangs, A., additional, Lieder, M., additional, Lovis, C., additional, Magrin, D., additional, Maxted, P. F. L., additional, Nascimbeni, V., additional, Ottensamer, R., additional, Pagano, I., additional, Pallé, E., additional, Peter, G., additional, Piotto, G., additional, Pizarro Rubio, A., additional, Pollacco, D., additional, Pozuelos, F. J., additional, Queloz, D., additional, Ragazzoni, R., additional, Rando, N., additional, Rauer, H., additional, Ribas, I., additional, Santos, N. C., additional, Scandariato, G., additional, Smith, A. M. S., additional, Sousa, S. G., additional, Steller, M., additional, Szabó, Gy. M., additional, Ségransan, D., additional, Thomas, N., additional, Udry, S., additional, Ulmer, B., additional, Van Grootel, V., additional, and Walton, N. A., additional

Published
2021
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209. A large sub-Neptune transiting the thick-disk M4 V TOI-2406

Author

Wells, R. D., primary, Rackham, B. V., additional, Schanche, N., additional, Petrucci, R., additional, Gómez Maqueo Chew, Y., additional, Demory, B.-O., additional, Burgasser, A. J., additional, Burn, R., additional, Pozuelos, F. J., additional, Günther, M. N., additional, Sabin, L., additional, Schroffenegger, U., additional, Gómez-Muñoz, M. A., additional, Stassun, K. G., additional, Van Grootel, V., additional, Howell, S. B., additional, Sebastian, D., additional, Triaud, A. H. M. J., additional, Apai, D., additional, Plauchu-Frayn, I., additional, Guerrero, C. A., additional, Guillén, P. F., additional, Landa, A., additional, Melgoza, G., additional, Montalvo, F., additional, Serrano, H., additional, Riesgo, H., additional, Barkaoui, K., additional, Bixel, A., additional, Burdanov, A., additional, Chen, W. P., additional, Chinchilla, P., additional, Collins, K. A., additional, Daylan, T., additional, de Wit, J., additional, Delrez, L., additional, Dévora-Pajares, M., additional, Dietrich, J., additional, Dransfield, G., additional, Ducrot, E., additional, Fausnaugh, M., additional, Furlan, E., additional, Gabor, P., additional, Gan, T., additional, Garcia, L., additional, Ghachoui, M., additional, Giacalone, S., additional, Gibbs, A. B., additional, Gillon, M., additional, Gnilka, C., additional, Gore, R., additional, Guerrero, N., additional, Henning, T., additional, Hesse, K., additional, Jehin, E., additional, Jenkins, J. M., additional, Latham, D. W., additional, Lester, K., additional, McCormac, J., additional, Murray, C. A., additional, Niraula, P., additional, Pedersen, P. P., additional, Queloz, D., additional, Ricker, G., additional, Rodriguez, D. R., additional, Schroeder, A., additional, Schwarz, R. P., additional, Scott, N., additional, Seager, S., additional, Theissen, C. A., additional, Thompson, S., additional, Timmermans, M., additional, Twicken, J. D., additional, and Winn, J. N., additional

Published
2021
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210. SPECULOOS: Ultracool dwarf transit survey

Author

Sebastian, D., Gillon, M., Ducrot, E., Pozuelos, F. J., Garcia, L. J., Günther, M. N., Delrez, L., Queloz, D., Demory, B. O., Triaud, A. H. M. J., Burgasser, A., de Wit, J., Burdanov, A., Dransfield, G., Jehin, E., McCormac, J., Murray, C. A., Niraula, P., Pedersen, P. P., Rackham, B. V., Sohy, S., Thompson, S., and Van Grootel, V.

Subjects
520 Astronomy, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Context. One of the most promising avenues for the detailed study of temperate Earth-sized exoplanets is the detection of such planets in transit in front of stars that are small and near enough to make it possible to carry out a thorough atmospheric characterisation with next-generation telescopes, such as the James Webb Space telescope (JWST) or Extremely Large Telescope (ELT). In this context, the TRAPPIST-1 planets form a unique benchmark system that has garnered the interest of a large scientific community. Aims. The SPECULOOS survey is an exoplanet transit survey targeting a volume-limited (40 pc) sample of ultracool dwarf stars (of spectral type M7 and later) that is based on a network of robotic 1 m telescopes especially designed for this survey. The strategy for brighter and earlier targets leverages on the synergy with the ongoing TESS space-based exoplanet transit survey. Methods. We define the SPECULOOS target list as the sum of three non-overlapping sub-programmes incorporating the latest type objects (Teff ≲ 3000 K). Programme 1 features 365 dwarfs that are small and near enough to make it possible to detail atmospheric characterisation of an ‘Earth-like’ planet with the upcoming JWST. Programme 2 features 171 dwarfs of M5-type and later for which a significant detection of a planet similar to TRAPPIST-1b should be within reach of TESS. Programme 3 features 1121 dwarfs that are later than M6-type. These programmes form the basis of our statistical census of short-period planets around ultracool dwarf stars. Results. Our compound target list includes 1657 photometrically classified late-type dwarfs, with 260 of these targets classified, for the first time, as possible nearby ultracool dwarf stars. Our general observational strategy was to monitor each target between 100 and 200 h with our telescope network, making efficient use of the synergy with TESS for our Programme 2 targets and a proportion of targets in our Programme 1. Conclusions. Based on Monte Carlo simulations, we expect to detect up to a few dozen temperate, rocky planets. We also expect a number of them to prove amenable for atmospheric characterisation with JWST and other future giant telescopes, which will substantially improve our understanding of the planetary population of the latest-type stars.

Published
2021
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211. enCHEOPS observations of the HD 108236 planetary system: a fifth planet, improved ephemerides, and planetary radii

Author

Bonfanti, A., Delrez, L., Hooton, M. J., Wilson, T. G., Fossati, L., Alibert, Y., Hoyer, S., Mustill, A. J., Osborn, H. P., Adibekyan, V., Gandolfi, D., Salmon, S., Sousa, S. G., Tuson, A., Van Grootel, V., Cabrera, J., Nascimbeni, V., Maxted, P. F. L., Barros, S. C. C., Billot, N., Bonfils, X., Borsato, L., Broeg, C., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Fridlund, M., Lacedelli, G., Lendl, M., Persson, C., Santos, N. C., Scandariato, G., Szabó, Gy. M., Collier Cameron, A., Udry, S., Benz, W., Beck, M., Ehrenreich, D., Fortier, A., Isaak, K. G., Queloz, D., Alonso, R., Asquier, J., Bandy, T., Bárczy, T., Barrado, D., Barragán, O., Baumjohann, W., Beck, T., Bekkelien, A., Bergomi, M., Brandeker, A., Busch, M.-D., Cessa, V., Charnoz, S., Chazelas, B., Corral Van Damme, C., Demory, B.-O., Erikson, A., Farinato, J., Futyan, D., Garcia Muñoz, A., Gillon, M., Guedel, M., Guterman, P., Hasiba, J., Heng, K., Hernandez, E., Kiss, L., Kuntzer, T., Laskar, J., Lecavelier des Etangs, A., Lovis, C., Magrin, D., Malvasio, L., Marafatto, L., Michaelis, H., Munari, M., Olofsson, G., Ottacher, H., Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piazza, D., Piotto, G., Pollacco, D., Ragazzoni, R., Rando, N., Ratti, F., Rauer, H., Ribas, I., Rieder, M., Rohlfs, R., Safa, F., Salatti, M., Ségransan, D., Simon, A. E., Smith, A. M. S., Sordet, M., Steller, M., Thomas, N., Tschentscher, M., Van Eylen, V., Viotto, V., Walter, I., Walton, N. A., Wildi, F., and Wolter, D.

Subjects
530 Physics, 520 Astronomy, 620 Engineering
Abstract

Context. The detection of a super-Earth and three mini-Neptunes transiting the bright (V = 9.2 mag) star HD 108236 (also known as TOI-1233) was recently reported on the basis of TESS and ground-based light curves. Aims. We perform a first characterisation of the HD 108236 planetary system through high-precision CHEOPS photometry and improve the transit ephemerides and system parameters. Methods. We characterise the host star through spectroscopic analysis and derive the radius with the infrared flux method. We constrain the stellar mass and age by combining the results obtained from two sets of stellar evolutionary tracks. We analyse the available TESS light curves and one CHEOPS transit light curve for each known planet in the system. Results. We find that HD 108236 is a Sun-like star with R⋆ = 0.877 ± 0.008 R⊙, M⋆ = 0.869−0.048+0.050 M⊙, and an age of 6.7−5.1+4.0 Gyr. We report the serendipitous detection of an additional planet, HD 108236 f, in one of the CHEOPS light curves. For this planet, the combined analysis of the TESS and CHEOPS light curves leads to a tentative orbital period of about 29.5 days. From the light curve analysis, we obtain radii of 1.615 ± 0.051, 2.071 ± 0.052, 2.539−0.065+0.062, 3.083 ± 0.052, and 2.017−0.057+0.052 R⊕ for planets HD 108236 b to HD 108236 f, respectively. These values are in agreement with previous TESS-based estimates, but with an improved precision of about a factor of two. We perform a stability analysis of the system, concluding that the planetary orbits most likely have eccentricities smaller than 0.1. We also employ a planetary atmospheric evolution framework to constrain the masses of the five planets, concluding that HD 108236 b and HD 108236 c should have an Earth-like density, while the outer planets should host a low mean molecular weight envelope. Conclusions. The detection of the fifth planet makes HD 108236 the third system brighter than V = 10 mag to host more than four transiting planets. The longer time span enables us to significantly improve the orbital ephemerides such that the uncertainty on the transit times will be of the order of minutes for the years to come. A comparison of the results obtained from the TESS and CHEOPS light curves indicates that for a V ~ 9 mag solar-like star and a transit signal of ~500 ppm, one CHEOPS transit light curve ensures the same level of photometric precision as eight TESS transits combined, although this conclusion depends on the length and position of the gaps in the light curve.

Published
2021
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212. I. Methods and performance tests on light curves from Kepler , K2, TESS, and CHEOPS

Author

Van Grootel, V., Pozuelos, F. J., Thuillier, A., Charpinet, S., Delrez, L., Beck, M., Fortier, A., Hoyer, S., Sousa, S. G., Barlow, B. N., Billot, N., D��vora-Pajares, M., ��stensen, R. H., Alibert, Y., Alonso, R., Anglada Escud��, G., Asquier, J., Barrado, D., Barros, S. C. C., Baumjohann, W., Beck, T., Bekkelien, A., Benz, W., Bonfils, X., Brandeker, A., Broeg, C., Bruno, G., B��rczy, T., Cabrera, J., Cameron, A. C., Charnoz, S., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Demory, B.-O., Ehrenreich, D., Erikson, A., Fossati, L., Fridlund, M., Futyan, D., Gandolfi, D., Gillon, M., Guedel, M., Heng, K., Isaak, K. G., Kiss, L., Laskar, J., Lecavelier des Etangs, A., Lendl, M., Lovis, C., Magrin, D., Maxted, P. F. L., Mecina, M., Mustill, A. J., Nascimbeni, V., Olofsson, G., Ottensamer, R., Pagano, I., Pall��, E., Peter, G., Piotto, G., Plesseria, J.-Y., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Ribas, I., Santos, N. C., Scandariato, G., S��gransan, D., Silvotti, R., Simon, A. E., Smith, A. M. S., Steller, M., Szab��, G. M., Thomas, N., Udry, S., Viotto, V., Walton, N. A., Westerdorff, K., Wilson, T. G., Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Space Sciences, Technologies and Astrophysics Research Institute (STAR), Université de Liège, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève = University of Geneva (UNIGE), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre Spatial de Liège (CSL), ANR-17-CE31-0018,INSIDE,Inversion astérosismique de la stratification en carbone / oxygène des noyaux d'étoiles de faible masse évoluées(2017), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Cavendish Laboratory, University of Cambridge [UK] (CAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Instituto de Astrofísica e Ciências do Espaço (IASTRO), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Université de Genève (UNIGE), European Space Agency (ESA), Institut de Physique du Globe de Paris (IPGP), and Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 520 Astronomy, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Q1, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 620 Engineering, QB600, QC, Astrophysics::Galaxy Astrophysics, QB, QB799
Abstract

Context. Hot subdwarfs experienced strong mass loss on the red giant branch (RGB) and are now hot and small He-burning objects. These stars constitute excellent opportunities for addressing the question of the evolution of exoplanetary systems directly after the RGB phase of evolution.\ud \ud Aims. In this project we aim to perform a transit survey in all available light curves of hot subdwarfs from space-based telescopes (Kepler, K2, TESS, and CHEOPS) with our custom-made pipeline SHERLOCK in order to determine the occurrence rate of planets around these stars as a function of orbital period and planetary radius. We also aim to determine whether planets that were previously engulfed in the envelope of their red giant host star can survive, even partially, as a planetary remnant.\ud \ud Methods. For this first paper, we performed injection-and-recovery tests of synthetic transits for a selection of representative Kepler, K2, and TESS light curves to determine which transiting bodies in terms of object radius and orbital period we will be able to detect with our tools. We also provide estimates for CHEOPS data, which we analyzed with the pycheops package.\ud \ud Results. Transiting objects with a radius less than or similar to 1.0 R-circle times can be detected in most of the Kepler, K2, and CHEOPS targets for the shortest orbital periods (1 d and shorter), reaching values as low as similar to 0.3 R-circle times in the best cases. Sub-Earth-sized bodies are only reached for the brightest TESS targets and for those that were observed in a significant number of sectors. We also give a series of representative results for larger planets at greater distances, which strongly depend on the target magnitude and on the length and quality of the data.\ud \ud Conclusions. The TESS sample will provide the most important statistics for the global aim of measuring the planet occurrence rate around hot subdwarfs. The Kepler, K2, and CHEOPS data will allow us to search for planetary remnants, that is, very close and small (possibly disintegrating) objects.

Published
2021
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213. The EBLM project – VIII. First results for M-dwarf mass, radius, and effective temperature measurements using CHEOPS light curves

Author

Swayne, M., Maxted, P. F. L., Triaud, A. H. M. J., Sousa, S. G., Broeg, C., Florén, Hans Gustav Axel, Guterman, P., Simon, A. E., Boisse, I., Bonfanti, A., Martin, D., Santerne, A., Salmon, S., Standing, M. R., Van Grootel, V., Wilson, T. G., Alibert, Y., Alonso, R., Anglada Escudé, G., Asquier, J., Bárczy, T., Barrado, D., Barros, S. C. C., Battley, M., Baumjohann, W., Beck, M., Beck, T., Bekkelien, A., Benz, W., Billot, N., Bonfils, X., Brandeker, Alexis, Busch, M.-D., Cabrera, J., Charnoz, S., Collier Cameron, A., Csizmadia, Sz., Davies, M. B., Deleuil, M., Deline, A., Delrez, L., Demangeon, O. D. S., Demory, B.-O., Dransfield, G., Ehrenreich, D., Erikson, A., Fortier, A., Fossati, L., Fridlund, M., Futyan, D., Gandolfi, D., Gillon, M., Guedel, M., Hébrard, G., Heidari, N., Hellier, C., Heng, K., Hobson, M., Hoyer, S., Isaak, K. G., Kiss, L., Kunovac Hodžić, V., Lalitha, S., Laskar, J., Lecavelier des Etangs, A., Lendl, M., Lovis, C., Magrin, D., Marafatto, L., McCormac, J., Miller, N., Nascimbeni, V., Olofsson, Göran, Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piotto, G., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Ribas, I., Santos, N. C., Scandariato, G., Ségransan, D., Smith, A. M. S., Steinberger, M., Steller, M., Szabó, Gy. M., Thomas, N., Udry, S., Walter, I., Walton, N. A., Willett, E., Swayne, M., Maxted, P. F. L., Triaud, A. H. M. J., Sousa, S. G., Broeg, C., Florén, Hans Gustav Axel, Guterman, P., Simon, A. E., Boisse, I., Bonfanti, A., Martin, D., Santerne, A., Salmon, S., Standing, M. R., Van Grootel, V., Wilson, T. G., Alibert, Y., Alonso, R., Anglada Escudé, G., Asquier, J., Bárczy, T., Barrado, D., Barros, S. C. C., Battley, M., Baumjohann, W., Beck, M., Beck, T., Bekkelien, A., Benz, W., Billot, N., Bonfils, X., Brandeker, Alexis, Busch, M.-D., Cabrera, J., Charnoz, S., Collier Cameron, A., Csizmadia, Sz., Davies, M. B., Deleuil, M., Deline, A., Delrez, L., Demangeon, O. D. S., Demory, B.-O., Dransfield, G., Ehrenreich, D., Erikson, A., Fortier, A., Fossati, L., Fridlund, M., Futyan, D., Gandolfi, D., Gillon, M., Guedel, M., Hébrard, G., Heidari, N., Hellier, C., Heng, K., Hobson, M., Hoyer, S., Isaak, K. G., Kiss, L., Kunovac Hodžić, V., Lalitha, S., Laskar, J., Lecavelier des Etangs, A., Lendl, M., Lovis, C., Magrin, D., Marafatto, L., McCormac, J., Miller, N., Nascimbeni, V., Olofsson, Göran, Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piotto, G., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Ribas, I., Santos, N. C., Scandariato, G., Ségransan, D., Smith, A. M. S., Steinberger, M., Steller, M., Szabó, Gy. M., Thomas, N., Udry, S., Walter, I., Walton, N. A., and Willett, E.

Abstract

The accuracy of theoretical mass, radius, and effective temperature values for M-dwarf stars is an active topic of debate. Differences between observed and theoretical values have raised the possibility that current theoretical stellar structure and evolution models are inaccurate towards the low-mass end of the main sequence. To explore this issue, we use the CHEOPS satellite to obtain high-precision light curves of eclipsing binaries with low-mass stellar companions. We use these light curves combined with the spectroscopic orbit for the solar-type companion to measure the mass, radius, and effective temperature of the M-dwarf star. Here, we present the analysis of three eclipsing binaries. We use the PYCHEOPS data analysis software to fit the observed transit and eclipse events of each system. Two of our systems were also observed by the TESS satellite – we similarly analyse these light curves for comparison. We find consistent results between CHEOPS and TESS, presenting three stellar radii and two stellar effective temperature values of low-mass stellar objects. These initial results from our on-going observing programme with CHEOPS show that we can expect to have ∼24 new mass, radius, and effective temperature measurements for very low-mass stars within the next few years.

Published
2021
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214. The changing face of AU Mic b : stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS

Author

Szabo, Gy M., Gandolfi, D., Brandeker, Alexis, Csizmadia, Sz, Garai, Z., Billot, N., Broeg, C., Ehrenreich, D., Fortier, A., Fossati, L., Hoyer, S., Kiss, L., Lecavelier des Etangs, A., Maxted, P. F. L., Ribas, I., Alibert, Y., Alonso, R., Anglada Escude, G., Barczy, T., Barros, S. C. C., Barrado, D., Baumjohann, W., Beck, M., Beck, T., Bekkelien, A., Bonfils, X., Benz, W., Borsato, L., Busch, M.-D., Cabrera, J., Charnoz, S., Collier Cameron, A., Corral Van Damme, C., Davies, M. B., Delrez, L., Deleuil, M., Demangeon, O. D. S., Demory, B.-O., Erikson, A., Fridlund, M., Futyan, D., Garcia Munoz, A., Gillon, M., Guedel, M., Guterman, P., Heng, K., Isaak, K. G., Lacedelli, G., Laskar, J., Lendl, M., Lovis, C., Luntzer, A., Magrin, D., Nascimbeni, V., Olofsson, Göran, Osborn, H. P., Ottensamer, R., Pagano, I., Palle, E., Peter, G., Piazza, D., Piotto, G., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Santos, N. C., Scandariato, G., Segransan, D., Serrano, L. M., Sicilia, D., Simon, A. E., Smith, A. M. S., Sousa, S. G., Steller, M., Thomas, N., Udry, S., Van Grootel, V., Walton, N. A., Wilson, T. G., Szabo, Gy M., Gandolfi, D., Brandeker, Alexis, Csizmadia, Sz, Garai, Z., Billot, N., Broeg, C., Ehrenreich, D., Fortier, A., Fossati, L., Hoyer, S., Kiss, L., Lecavelier des Etangs, A., Maxted, P. F. L., Ribas, I., Alibert, Y., Alonso, R., Anglada Escude, G., Barczy, T., Barros, S. C. C., Barrado, D., Baumjohann, W., Beck, M., Beck, T., Bekkelien, A., Bonfils, X., Benz, W., Borsato, L., Busch, M.-D., Cabrera, J., Charnoz, S., Collier Cameron, A., Corral Van Damme, C., Davies, M. B., Delrez, L., Deleuil, M., Demangeon, O. D. S., Demory, B.-O., Erikson, A., Fridlund, M., Futyan, D., Garcia Munoz, A., Gillon, M., Guedel, M., Guterman, P., Heng, K., Isaak, K. G., Lacedelli, G., Laskar, J., Lendl, M., Lovis, C., Luntzer, A., Magrin, D., Nascimbeni, V., Olofsson, Göran, Osborn, H. P., Ottensamer, R., Pagano, I., Palle, E., Peter, G., Piazza, D., Piotto, G., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Santos, N. C., Scandariato, G., Segransan, D., Serrano, L. M., Sicilia, D., Simon, A. E., Smith, A. M. S., Sousa, S. G., Steller, M., Thomas, N., Udry, S., Van Grootel, V., Walton, N. A., and Wilson, T. G.

Abstract

AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 +/- 0.000003 d, whereas the stellar rotational period is P-rot = 4.8367 +/- 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10% in the planet-to-star radius ratio and the accuracy on transit time by 3-4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs.

Published
2021
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215. Exploiting timing capabilities of the CHEOPS mission with warm-Jupiter planets

Author

Borsato, L., Piotto, G., Gandolfi, D., Nascimbeni, V, Lacedelli, G., Marzari, F., Billot, N., Maxted, P. F. L., Sousa, S., Cameron, A. C., Bonfanti, A., Wilson, T. G., Serrano, L. M., Garai, Z., Alibert, Y., Alonso, R., Asquier, J., Bárczy, T., Bandy, T., Barrado, D., Barros, S. C. C., Baumjohann, W., Beck, M., Beck, T., Benz, W., Bonfils, X., Brandeker, Alexis, Broeg, C., Cabrera, J., Charnoz, S., Csizmadia, S., Davies, M. B., Deleuil, M., Delrez, L., Demangeon, O., Demory, B-O, des Etangs, A. L., Ehrenreich, D., Erikson, A., Escudé, G. A., Fortier, A., Fossati, L., Fridlund, M., Gillon, M., Guedel, M., Hasiba, J., Heng, K., Hoyer, S., Isaak, K. G., Kiss, L., Kopp, E., Laskar, J., Lendl, M., Lovis, C., Magrin, D., Munari, M., Olofsson, Göran, Ottensamer, R., Pagano, I, Pallé, E., Peter, G., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Ribas, I, Ségransan, D., Santos, N. C., Scandariato, G., Simon, A., Smith, A. M. S., Steller, M., Szabó, G., Thomas, N., Udry, S., Van Grootel, V., Walton, N., Borsato, L., Piotto, G., Gandolfi, D., Nascimbeni, V, Lacedelli, G., Marzari, F., Billot, N., Maxted, P. F. L., Sousa, S., Cameron, A. C., Bonfanti, A., Wilson, T. G., Serrano, L. M., Garai, Z., Alibert, Y., Alonso, R., Asquier, J., Bárczy, T., Bandy, T., Barrado, D., Barros, S. C. C., Baumjohann, W., Beck, M., Beck, T., Benz, W., Bonfils, X., Brandeker, Alexis, Broeg, C., Cabrera, J., Charnoz, S., Csizmadia, S., Davies, M. B., Deleuil, M., Delrez, L., Demangeon, O., Demory, B-O, des Etangs, A. L., Ehrenreich, D., Erikson, A., Escudé, G. A., Fortier, A., Fossati, L., Fridlund, M., Gillon, M., Guedel, M., Hasiba, J., Heng, K., Hoyer, S., Isaak, K. G., Kiss, L., Kopp, E., Laskar, J., Lendl, M., Lovis, C., Magrin, D., Munari, M., Olofsson, Göran, Ottensamer, R., Pagano, I, Pallé, E., Peter, G., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Ribas, I, Ségransan, D., Santos, N. C., Scandariato, G., Simon, A., Smith, A. M. S., Steller, M., Szabó, G., Thomas, N., Udry, S., Van Grootel, V., and Walton, N.

Abstract

We present 17 transit light curves of seven known warm-Jupiters observed with the CHaracterising ExOPlanet Satellite (CHEOPS). The light curves have been collected as part of the CHEOPS Guaranteed Time Observation (GTO) program that searches for transit-timing variation (TTV) of warm-Jupiters induced by a possible external perturber to shed light on the evolution path of such planetary systems. We describe the CHEOPS observation process, from the planning to the data analysis. In this work, we focused on the timing performance of CHEOPS, the impact of the sampling of the transit phases, and the improvement we can obtain by combining multiple transits together. We reached the highest precision on the transit time of about 13–16 s for the brightest target (WASP-38, G = 9.2) in our sample. From the combined analysis of multiple transits of fainter targets with G ≥ 11, we obtained a timing precision of ∼2 min. Additional observations with CHEOPS, covering a longer temporal baseline, will further improve the precision on the transit times and will allow us to detect possible TTV signals induced by an external perturber.

Published
2021
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216. A search for transiting planets around hot subdwarfs I. Methods and performance tests on light curves from Kepler, K2, TESS, and CHEOPS

Author

Van Grootel, V., Pozuelos, F. J., Thuillier, A., Charpinet, S., Delrez, L., Beck, M., Fortier, A., Hoyer, S., Sousa, S. G., Barlow, B. N., Billot, N., Dévora-Pajares, M., Østensen, R. H., Alibert, Y., Alonso, R., Anglada Escudé, G., Asquier, J., Barrado, D., Barros, S. C. C., Baumjohann, W., Beck, T., Bekkelien, A., Benz, W., Bonfils, X., Brandeker, Alexis, Broeg, C., Bruno, G., Bárczy, T., Cabrera, J., Cameron, A. C., Charnoz, S., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Demory, B-O., Ehrenreich, D., Erikson, A., Fossati, L., Fridlund, M., Futyan, D., Gandolfi, D., Gillon, M., Guedel, M., Heng, K., Isaak, K. G., Kiss, L., Laskar, J., Lecavelier des Etangs, A., Lendl, M., Lovis, C., Magrin, D., Maxted, P. F. L., Mecina, M., Mustill, A. J., Nascimbeni, V., Olofsson, Göran, Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piotto, G., Plesseria, J-Y., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Ribas, I., Santos, N. C., Scandariato, G., Ségransan, D., Silvotti, R., Simon, A. E., Smith, A. M. S., Steller, M., Szabó, G. M., Thomas, N., Udry, S., Viotto, V., Walton, N. A., Westerdorff, K., Wilson, T. G., Van Grootel, V., Pozuelos, F. J., Thuillier, A., Charpinet, S., Delrez, L., Beck, M., Fortier, A., Hoyer, S., Sousa, S. G., Barlow, B. N., Billot, N., Dévora-Pajares, M., Østensen, R. H., Alibert, Y., Alonso, R., Anglada Escudé, G., Asquier, J., Barrado, D., Barros, S. C. C., Baumjohann, W., Beck, T., Bekkelien, A., Benz, W., Bonfils, X., Brandeker, Alexis, Broeg, C., Bruno, G., Bárczy, T., Cabrera, J., Cameron, A. C., Charnoz, S., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Demory, B-O., Ehrenreich, D., Erikson, A., Fossati, L., Fridlund, M., Futyan, D., Gandolfi, D., Gillon, M., Guedel, M., Heng, K., Isaak, K. G., Kiss, L., Laskar, J., Lecavelier des Etangs, A., Lendl, M., Lovis, C., Magrin, D., Maxted, P. F. L., Mecina, M., Mustill, A. J., Nascimbeni, V., Olofsson, Göran, Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piotto, G., Plesseria, J-Y., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Ribas, I., Santos, N. C., Scandariato, G., Ségransan, D., Silvotti, R., Simon, A. E., Smith, A. M. S., Steller, M., Szabó, G. M., Thomas, N., Udry, S., Viotto, V., Walton, N. A., Westerdorff, K., and Wilson, T. G.

Abstract

Context. Hot subdwarfs experienced strong mass loss on the red giant branch (RGB) and are now hot and small He-burning objects. These stars constitute excellent opportunities for addressing the question of the evolution of exoplanetary systems directly after the RGB phase of evolution. Aims. In this project we aim to perform a transit survey in all available light curves of hot subdwarfs from space-based telescopes (Kepler, K2, TESS, and CHEOPS) with our custom-made pipeline SHERLOCK in order to determine the occurrence rate of planets around these stars as a function of orbital period and planetary radius. We also aim to determine whether planets that were previously engulfed in the envelope of their red giant host star can survive, even partially, as a planetary remnant. Methods. For this first paper, we performed injection-and-recovery tests of synthetic transits for a selection of representative Kepler, K2, and TESS light curves to determine which transiting bodies in terms of object radius and orbital period we will be able to detect with our tools. We also provide estimates for CHEOPS data, which we analyzed with the pycheops package. Results. Transiting objects with a radius ≲1.0 R⊕ can be detected in most of the Kepler, K2, and CHEOPS targets for the shortest orbital periods (1 d and shorter), reaching values as low as ~0.3 R⊕ in the best cases. Sub-Earth-sized bodies are only reached for the brightest TESS targets and for those that were observed in a significant number of sectors. We also give a series of representative results for larger planets at greater distances, which strongly depend on the target magnitude and on the length and quality of the data. Conclusions. The TESS sample will provide the most important statistics for the global aim of measuring the planet occurrence rate around hot subdwarfs. The Kepler, K2, and CHEOPS data will allow us to search for planetary remnants, that is, very close and small (possibly disintegrating) objects.

Published
2021
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217. Development of the SPECULOOS exoplanet search project

Author

Sebastian, D., Pedersen, P. P., Murray, C. A., Ducrot, E., Garcia, L. J., Burdanov, A., Pozuelos, F. J., Delrez, L., Wells, R., Dransfield, G., Gillon, M., Demory, B. -O., Queloz, D., Triaud, A. H. M. J., de Wit, J., Jehin, E., Chew, Y. Gómez Maqueo, Günther, M. N., Niraula, P., Rackham, B. V., Schanche, N., Sohy, S., Thompson, S., Sebastian, D., Pedersen, P. P., Murray, C. A., Ducrot, E., Garcia, L. J., Burdanov, A., Pozuelos, F. J., Delrez, L., Wells, R., Dransfield, G., Gillon, M., Demory, B. -O., Queloz, D., Triaud, A. H. M. J., de Wit, J., Jehin, E., Chew, Y. Gómez Maqueo, Günther, M. N., Niraula, P., Rackham, B. V., Schanche, N., Sohy, S., and Thompson, S.

Abstract

SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) aims to perform a transit search on the nearest ($<40$pc) ultracool ($<3000$K) dwarf stars. The project's main motivation is to discover potentially habitable planets well-suited for detailed atmospheric characterisation with upcoming giant telescopes, like the James Webb Space Telescope (JWST) and European Large Telescope (ELT). The project is based on a network of 1m robotic telescopes, namely the four ones of the SPECULOOS-Southern Observatory (SSO) in Cerro Paranal, Chile, one telescope of the SPECULOOS-Northern Observatory (SNO) in Tenerife, and the SAINT-Ex telescope in San Pedro M\'artir, Mexico. The prototype survey of the SPECULOOS project on the 60~cm TRAPPIST telescope (Chile) discovered the TRAPPIST-1 system, composed of seven temperate Earth-sized planets orbiting a nearby (12~pc) Jupiter-sized star. In this paper, we review the current status of SPECULOOS, its first results, the plans for its development, and its connection to the Transiting Exoplanet Survey Satellite (TESS) and JWST., Comment: 16 pages, 3 figures, 1 table. Proceedings of SPIE

Published
2021
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218. Six transiting planets and a chain of Laplace resonances in TOI-178

Author

Leleu, A., Alibert, Y., Hara, N. C., Hooton, M. J., Wilson, T. G., Robutel, P., Delisle, J. -B., Laskar, J., Hoyer, S., Lovis, C., Bryant, E. M., Ducrot, E., Cabrera, J., Delrez, L., Acton, J. S., Adibekyan, V., Allart, R., Prieto, C. Allende, Alonso, R., Alves, D., Anderson, D. R., Angerhausen, D., Escudé, G. Anglada, Asquier, J., Barrado, D., Barros, S. C. C., Baumjohann, W., Bayliss, D., Beck, M., Beck, T., Bekkelien, A., Benz, W., Billot, N., Bonfanti, A., Bonfils, X., Bouchy, F., Bourrier, V., Boué, G., Brandeker, A., Broeg, C., Buder, M., Burdanov, A., Burleigh, M. R., Bárczy, T., Cameron, A. C., Chamberlain, S., Charnoz, S., Cooke, B. F., Van Damme, C. Corral, Correia, A. C. M., Cristiani, S., Damasso, M., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Demory, B. -O., Di Marcantonio, P., Di Persio, G., Dumusque, X., Ehrenreich, D., Erikson, A., Figueira, P., Fortier, A., Fossati, L., Fridlund, M., Futyan, D., Gandolfi, D., Muñoz, A. García, Garcia, L. J., Gill, S., Gillen, E., Gillon, M., Goad, M. R., Hernández, J. I. González, Guedel, M., Günther, M. N., Haldemann, J., Henderson, B., Heng, K., Hogan, A. E., Isaak, K., Jehin, E., Jenkins, J. S., Jordán, A., Kiss, L., Kristiansen, M. H., Lam, K., Lavie, B., Etangs, A. Lecavelier des, Lendl, M., Lillo-Box, J., Curto, G. Lo, Magrin, D., Martins, C. J. A. P., Maxted, P. F. L., McCormac, J., Mehner, A., Micela, G., Molaro, P., Moyano, M., Murray, C. A., Nascimbeni, V., Nunes, N. J., Olofsson, G., Osborn, H. P., Oshagh, M., Ottensamer, R., Pagano, I., Pallé, E., Pedersen, P. P., Pepe, F. A., Persson, C. M., Peter, G., Piotto, G., Polenta, G., Pollacco, D., Poretti, E., Pozuelos, F. J., Queloz, D., Ragazzoni, R., Rando, N., Ratti, F., Rauer, H., Raynard, L., Rebolo, R., Reimers, C., Ribas, I., Santos, N. C., Scandariato, G., Schneider, J., Sebastian, D., Sestovic, M., Simon, A. E., Smith, A. M. S., Sousa, S. G., Sozzetti, A., Steller, M., Mascareño, A. Suárez, Szabó, Gy. M., Ségransan, D., Thomas, N., Thompson, S., Tilbrook, R. H., Triaud, A., Turner, O., Udry, S., Van Grootel, V., Venus, H., Verrecchia, F., Vines, J. I., Walton, N. A., West, R. G., Wheatley, P. J., Wolter, D., Osorio, M. R. Zapatero, Leleu, A., Alibert, Y., Hara, N. C., Hooton, M. J., Wilson, T. G., Robutel, P., Delisle, J. -B., Laskar, J., Hoyer, S., Lovis, C., Bryant, E. M., Ducrot, E., Cabrera, J., Delrez, L., Acton, J. S., Adibekyan, V., Allart, R., Prieto, C. Allende, Alonso, R., Alves, D., Anderson, D. R., Angerhausen, D., Escudé, G. Anglada, Asquier, J., Barrado, D., Barros, S. C. C., Baumjohann, W., Bayliss, D., Beck, M., Beck, T., Bekkelien, A., Benz, W., Billot, N., Bonfanti, A., Bonfils, X., Bouchy, F., Bourrier, V., Boué, G., Brandeker, A., Broeg, C., Buder, M., Burdanov, A., Burleigh, M. R., Bárczy, T., Cameron, A. C., Chamberlain, S., Charnoz, S., Cooke, B. F., Van Damme, C. Corral, Correia, A. C. M., Cristiani, S., Damasso, M., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Demory, B. -O., Di Marcantonio, P., Di Persio, G., Dumusque, X., Ehrenreich, D., Erikson, A., Figueira, P., Fortier, A., Fossati, L., Fridlund, M., Futyan, D., Gandolfi, D., Muñoz, A. García, Garcia, L. J., Gill, S., Gillen, E., Gillon, M., Goad, M. R., Hernández, J. I. González, Guedel, M., Günther, M. N., Haldemann, J., Henderson, B., Heng, K., Hogan, A. E., Isaak, K., Jehin, E., Jenkins, J. S., Jordán, A., Kiss, L., Kristiansen, M. H., Lam, K., Lavie, B., Etangs, A. Lecavelier des, Lendl, M., Lillo-Box, J., Curto, G. Lo, Magrin, D., Martins, C. J. A. P., Maxted, P. F. L., McCormac, J., Mehner, A., Micela, G., Molaro, P., Moyano, M., Murray, C. A., Nascimbeni, V., Nunes, N. J., Olofsson, G., Osborn, H. P., Oshagh, M., Ottensamer, R., Pagano, I., Pallé, E., Pedersen, P. P., Pepe, F. A., Persson, C. M., Peter, G., Piotto, G., Polenta, G., Pollacco, D., Poretti, E., Pozuelos, F. J., Queloz, D., Ragazzoni, R., Rando, N., Ratti, F., Rauer, H., Raynard, L., Rebolo, R., Reimers, C., Ribas, I., Santos, N. C., Scandariato, G., Schneider, J., Sebastian, D., Sestovic, M., Simon, A. E., Smith, A. M. S., Sousa, S. G., Sozzetti, A., Steller, M., Mascareño, A. Suárez, Szabó, Gy. M., Ségransan, D., Thomas, N., Thompson, S., Tilbrook, R. H., Triaud, A., Turner, O., Udry, S., Van Grootel, V., Venus, H., Verrecchia, F., Vines, J. I., Walton, N. A., West, R. G., Wheatley, P. J., Wolter, D., and Osorio, M. R. Zapatero

Abstract

Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at a 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152(-0.070/+0.073) to 2.87(-0.13/+0.14) Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02(+0.28/-0.23) to 0.177(+0.055/-0.061) times the Earth's density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.

Published
2021
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219. CHEOPS observations of the HD 108236 planetary system: A fifth planet, improved ephemerides, and planetary radii

Author

Bonfanti, A., Delrez, L., Hooton, M. J., Wilson, T. G., Fossati, L., Alibert, Y., Hoyer, S., Mustill, A. J., Osborn, H. P., Adibekyan, V., Gandolfi, D., Salmon, S., Sousa, S. G., Tuson, A., Van Grootel, V., Cabrera, J., Nascimbeni, V., Maxted, P. F. L., Barros, S. C. C., Billot, N., Bonfils, X., Borsato, L., Broeg, C., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Fridlund, M., Lacedelli, G., Lendl, M., Persson, C., Santos, N. C., Scandariato, G., Szabó, Gy. M., Cameron, A. Collier, Udry, S., Benz, W., Beck, M., Ehrenreich, D., Fortier, A., Isaak, K. G., Queloz, D., Alonso, R., Asquier, J., Bandy, T., Bárczy, T., Barrado, D., Barragán, O., Baumjohann, W., Beck, T., Bekkelien, A., Bergomi, M., Busch, M-D., Brandeker, A., Cessa, V., Charnoz, S., Chazelas, B., Van Damme, C. Corral, Demory, B. -O., Erikson, A., Farinato, J., Futyan, D., Muñoz, A. Garcia, Gillon, M., Guedel, M., Guterman, P., Hasiba, J., Heng, K., Hernandez, E., Kiss, L., Kuntzer, T., Laskar, J., Etangs, A. Lecavelier des, Lovis, C., Magrin, D., Malvasio, L., Marafatto, L., Michaelis, H., Munari, M., Olofsson, G., Ottacher, H., Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piazza, D., Piotto, G., Pollacco, D., Ragazzoni, R., Rando, N., Ratti, F., Rauer, H., Ribas, I., Rieder, M., Rohlfs, R., Safa, F., Salatti, M., Ségransan, D., Simon, A. E., Smith, A. M. S., Sordet, M., Steller, M., Thomas, N., Tschentscher, M., Van Eylen, V., Viotto, V., Walter, I., Walton, N. A., Wildi, F., Wolter, D., Bonfanti, A., Delrez, L., Hooton, M. J., Wilson, T. G., Fossati, L., Alibert, Y., Hoyer, S., Mustill, A. J., Osborn, H. P., Adibekyan, V., Gandolfi, D., Salmon, S., Sousa, S. G., Tuson, A., Van Grootel, V., Cabrera, J., Nascimbeni, V., Maxted, P. F. L., Barros, S. C. C., Billot, N., Bonfils, X., Borsato, L., Broeg, C., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Fridlund, M., Lacedelli, G., Lendl, M., Persson, C., Santos, N. C., Scandariato, G., Szabó, Gy. M., Cameron, A. Collier, Udry, S., Benz, W., Beck, M., Ehrenreich, D., Fortier, A., Isaak, K. G., Queloz, D., Alonso, R., Asquier, J., Bandy, T., Bárczy, T., Barrado, D., Barragán, O., Baumjohann, W., Beck, T., Bekkelien, A., Bergomi, M., Busch, M-D., Brandeker, A., Cessa, V., Charnoz, S., Chazelas, B., Van Damme, C. Corral, Demory, B. -O., Erikson, A., Farinato, J., Futyan, D., Muñoz, A. Garcia, Gillon, M., Guedel, M., Guterman, P., Hasiba, J., Heng, K., Hernandez, E., Kiss, L., Kuntzer, T., Laskar, J., Etangs, A. Lecavelier des, Lovis, C., Magrin, D., Malvasio, L., Marafatto, L., Michaelis, H., Munari, M., Olofsson, G., Ottacher, H., Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piazza, D., Piotto, G., Pollacco, D., Ragazzoni, R., Rando, N., Ratti, F., Rauer, H., Ribas, I., Rieder, M., Rohlfs, R., Safa, F., Salatti, M., Ségransan, D., Simon, A. E., Smith, A. M. S., Sordet, M., Steller, M., Thomas, N., Tschentscher, M., Van Eylen, V., Viotto, V., Walter, I., Walton, N. A., Wildi, F., and Wolter, D.

Abstract

The detection of a super-Earth and three mini-Neptunes transiting the bright ($V$ = 9.2 mag) star HD 108236 (also known as TOI-1233) was recently reported on the basis of TESS and ground-based light curves. We perform a first characterisation of the HD 108236 planetary system through high-precision CHEOPS photometry and improve the transit ephemerides and system parameters. We characterise the host star through spectroscopic analysis and derive the radius with the infrared flux method. We constrain the stellar mass and age by combining the results obtained from two sets of stellar evolutionary tracks. We analyse the available TESS light curves and one CHEOPS transit light curve for each known planet in the system. We find that HD 108236 is a Sun-like star with $R_{\star}=0.877\pm0.008 R_{\odot}$, $M_{\star}=0.869^{+0.050}_{-0.048} M_{\odot}$, and an age of $6.7_{-5.1}^{+4.0}$ Gyr. We report the serendipitous detection of an additional planet, HD 108236 f, in one of the CHEOPS light curves. For this planet, the combined analysis of the TESS and CHEOPS light curves leads to a tentative orbital period of about 29.5 days. From the light curve analysis, we obtain radii of $1.615\pm0.051$, $2.071\pm0.052$, $2.539_{-0.065}^{+0.062}$, $3.083\pm0.052$, and $2.017_{-0.057}^{+0.052}$ $R_{\oplus}$ for planets HD 108236 b to HD 108236 f, respectively. These values are in agreement with previous TESS-based estimates, but with an improved precision of about a factor of two. We perform a stability analysis of the system, concluding that the planetary orbits most likely have eccentricities smaller than 0.1. We also employ a planetary atmospheric evolution framework to constrain the masses of the five planets, concluding that HD 108236 b and HD 108236 c should have an Earth-like density, while the outer planets should host a low mean molecular weight envelope., Comment: 20 pages, 14 figures, accepted for publication by A&A

Published
2021
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220. SPECULOOS: Ultracool dwarf transit survey: Target list and strategy

Author

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Sebastian, D, Gillon, M, Ducrot, E, Pozuelos, FJ, Garcia, LJ, Günther, MN, Delrez, L, Queloz, D, Demory, BO, Triaud, A HMJ, Burgasser, A, de Wit, J, Burdanov, A, Dransfield, G, Jehin, E, McCormac, J, Murray, C, Niraula, P, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Sebastian, D, Gillon, M, Ducrot, E, Pozuelos, FJ, Garcia, LJ, Günther, MN, Delrez, L, Queloz, D, Demory, BO, Triaud, A HMJ, Burgasser, A, de Wit, J, Burdanov, A, Dransfield, G, Jehin, E, McCormac, J, Murray, C, and Niraula, P

Abstract

© ESO 2021. Context. One of the most promising avenues for the detailed study of temperate Earth-sized exoplanets is the detection of such planets in transit in front of stars that are small and near enough to make it possible to carry out a thorough atmospheric characterisation with next-generation telescopes, such as the James Webb Space telescope (JWST) or Extremely Large Telescope (ELT). In this context, the TRAPPIST-1 planets form a unique benchmark system that has garnered the interest of a large scientific community. Aims. The SPECULOOS survey is an exoplanet transit survey targeting a volume-limited (40 pc) sample of ultracool dwarf stars (of spectral type M7 and later) that is based on a network of robotic 1 m telescopes especially designed for this survey. The strategy for brighter and earlier targets leverages on the synergy with the ongoing TESS space-based exoplanet transit survey. Methods. We define the SPECULOOS target list as the sum of three non-overlapping sub-programmes incorporating the latest type objects (Teff ≲ 3000 K). Programme 1 features 365 dwarfs that are small and near enough to make it possible to detail atmospheric characterisation of an 'Earth-like' planet with the upcoming JWST. Programme 2 features 171 dwarfs of M5-type and later for which a significant detection of a planet similar to TRAPPIST-1b should be within reach of TESS. Programme 3 features 1121 dwarfs that are later than M6-type. These programmes form the basis of our statistical census of short-period planets around ultracool dwarf stars. Results. Our compound target list includes 1657 photometrically classified late-type dwarfs, with 260 of these targets classified, for the first time, as possible nearby ultracool dwarf stars. Our general observational strategy was to monitor each target between 100 and 200 h with our telescope network, making efficient use of the synergy with TESS for our Programme 2 targets and a proportion of targets in our Programme 1. Conclusions.

Published
2021

221. Exploiting timing capabilities of the CHEOPS mission with warm-Jupiter planets

Author

Borsato, L, primary, Piotto, G, additional, Gandolfi, D, additional, Nascimbeni, V, additional, Lacedelli, G, additional, Marzari, F, additional, Billot, N, additional, Maxted, P F L, additional, Sousa, S, additional, Cameron, A C, additional, Bonfanti, A, additional, Wilson, T G, additional, Serrano, L M, additional, Garai, Z, additional, Alibert, Y, additional, Alonso, R, additional, Asquier, J, additional, Bárczy, T, additional, Bandy, T, additional, Barrado, D, additional, Barros, S C C, additional, Baumjohann, W, additional, Beck, M, additional, Beck, T, additional, Benz, W, additional, Bonfils, X, additional, Brandeker, A, additional, Broeg, C, additional, Cabrera, J, additional, Charnoz, S, additional, Csizmadia, S, additional, Davies, M B, additional, Deleuil, M, additional, Delrez, L, additional, Demangeon, O, additional, Demory, B-O, additional, des Etangs, A L, additional, Ehrenreich, D, additional, Erikson, A, additional, Escudé, G A, additional, Fortier, A, additional, Fossati, L, additional, Fridlund, M, additional, Gillon, M, additional, Guedel, M, additional, Hasiba, J, additional, Heng, K, additional, Hoyer, S, additional, Isaak, K G, additional, Kiss, L, additional, Kopp, E, additional, Laskar, J, additional, Lendl, M, additional, Lovis, C, additional, Magrin, D, additional, Munari, M, additional, Olofsson, G, additional, Ottensamer, R, additional, Pagano, I, additional, Pallé, E, additional, Peter, G, additional, Pollacco, D, additional, Queloz, D, additional, Ragazzoni, R, additional, Rando, N, additional, Rauer, H, additional, Ribas, I, additional, Ségransan, D, additional, Santos, N C, additional, Scandariato, G, additional, Simon, A, additional, Smith, A M S, additional, Steller, M, additional, Szabó, G, additional, Thomas, N, additional, Udry, S, additional, Van Grootel, V, additional, and Walton, N, additional

Published
2021
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222. The EBLM project – VIII. First results for M-dwarf mass, radius, and effective temperature measurements using CHEOPS light curves

Author

Swayne, M I, primary, Maxted, P F L, additional, Triaud, A H M J, additional, Sousa, S G, additional, Broeg, C, additional, Florén, H-G, additional, Guterman, P, additional, Simon, A E, additional, Boisse, I, additional, Bonfanti, A, additional, Martin, D, additional, Santerne, A, additional, Salmon, S, additional, Standing, M R, additional, Van Grootel, V, additional, Wilson, T G, additional, Alibert, Y, additional, Alonso, R, additional, Anglada Escudé, G, additional, Asquier, J, additional, Bárczy, T, additional, Barrado, D, additional, Barros, S C C, additional, Battley, M, additional, Baumjohann, W, additional, Beck, M, additional, Beck, T, additional, Bekkelien, A, additional, Benz, W, additional, Billot, N, additional, Bonfils, X, additional, Brandeker, A, additional, Busch, M-D, additional, Cabrera, J, additional, Charnoz, S, additional, Collier Cameron, A, additional, Csizmadia, Sz, additional, Davies, M B, additional, Deleuil, M, additional, Deline, A, additional, Delrez, L, additional, Demangeon, O D S, additional, Demory, B-O, additional, Dransfield, G, additional, Ehrenreich, D, additional, Erikson, A, additional, Fortier, A, additional, Fossati, L, additional, Fridlund, M, additional, Futyan, D, additional, Gandolfi, D, additional, Gillon, M, additional, Guedel, M, additional, Hébrard, G, additional, Heidari, N, additional, Hellier, C, additional, Heng, K, additional, Hobson, M, additional, Hoyer, S, additional, Isaak, K G, additional, Kiss, L, additional, Kunovac Hodžić, V, additional, Lalitha, S, additional, Laskar, J, additional, Lecavelier des Etangs, A, additional, Lendl, M, additional, Lovis, C, additional, Magrin, D, additional, Marafatto, L, additional, McCormac, J, additional, Miller, N, additional, Nascimbeni, V, additional, Olofsson, G, additional, Ottensamer, R, additional, Pagano, I, additional, Pallé, E, additional, Peter, G, additional, Piotto, G, additional, Pollacco, D, additional, Queloz, D, additional, Ragazzoni, R, additional, Rando, N, additional, Rauer, H, additional, Ribas, I, additional, Santos, N C, additional, Scandariato, G, additional, Ségransan, D, additional, Smith, A M S, additional, Steinberger, M, additional, Steller, M, additional, Szabó, Gy M, additional, Thomas, N, additional, Udry, S, additional, Walter, I, additional, Walton, N A, additional, and Willett, E, additional

Published
2021
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223. A search for transiting planets around hot subdwarfs

Author

Van Grootel, V., primary, Pozuelos, F. J., additional, Thuillier, A., additional, Charpinet, S., additional, Delrez, L., additional, Beck, M., additional, Fortier, A., additional, Hoyer, S., additional, Sousa, S. G., additional, Barlow, B. N., additional, Billot, N., additional, Dévora-Pajares, M., additional, Østensen, R. H., additional, Alibert, Y., additional, Alonso, R., additional, Anglada Escudé, G., additional, Asquier, J., additional, Barrado, D., additional, Barros, S. C. C., additional, Baumjohann, W., additional, Beck, T., additional, Bekkelien, A., additional, Benz, W., additional, Bonfils, X., additional, Brandeker, A., additional, Broeg, C., additional, Bruno, G., additional, Bárczy, T., additional, Cabrera, J., additional, Cameron, A. C., additional, Charnoz, S., additional, Davies, M. B., additional, Deleuil, M., additional, Demangeon, O. D. S., additional, Demory, B.-O., additional, Ehrenreich, D., additional, Erikson, A., additional, Fossati, L., additional, Fridlund, M., additional, Futyan, D., additional, Gandolfi, D., additional, Gillon, M., additional, Guedel, M., additional, Heng, K., additional, Isaak, K. G., additional, Kiss, L., additional, Laskar, J., additional, Lecavelier des Etangs, A., additional, Lendl, M., additional, Lovis, C., additional, Magrin, D., additional, Maxted, P. F. L., additional, Mecina, M., additional, Mustill, A. J., additional, Nascimbeni, V., additional, Olofsson, G., additional, Ottensamer, R., additional, Pagano, I., additional, Pallé, E., additional, Peter, G., additional, Piotto, G., additional, Plesseria, J.-Y., additional, Pollacco, D., additional, Queloz, D., additional, Ragazzoni, R., additional, Rando, N., additional, Rauer, H., additional, Ribas, I., additional, Santos, N. C., additional, Scandariato, G., additional, Ségransan, D., additional, Silvotti, R., additional, Simon, A. E., additional, Smith, A. M. S., additional, Steller, M., additional, Szabó, G. M., additional, Thomas, N., additional, Udry, S., additional, Viotto, V., additional, Walton, N. A., additional, Westerdorff, K., additional, and Wilson, T. G., additional

Published
2021
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224. Six transiting planets and a chain of Laplace resonances in TOI-178

Author

Leleu, A., primary, Alibert, Y., additional, Hara, N. C., additional, Hooton, M. J., additional, Wilson, T. G., additional, Robutel, P., additional, Delisle, J.-B., additional, Laskar, J., additional, Hoyer, S., additional, Lovis, C., additional, Bryant, E. M., additional, Ducrot, E., additional, Cabrera, J., additional, Delrez, L., additional, Acton, J. S., additional, Adibekyan, V., additional, Allart, R., additional, Allende Prieto, C., additional, Alonso, R., additional, Alves, D., additional, Anderson, D. R., additional, Angerhausen, D., additional, Anglada Escudé, G., additional, Asquier, J., additional, Barrado, D., additional, Barros, S. C. C., additional, Baumjohann, W., additional, Bayliss, D., additional, Beck, M., additional, Beck, T., additional, Bekkelien, A., additional, Benz, W., additional, Billot, N., additional, Bonfanti, A., additional, Bonfils, X., additional, Bouchy, F., additional, Bourrier, V., additional, Boué, G., additional, Brandeker, A., additional, Broeg, C., additional, Buder, M., additional, Burdanov, A., additional, Burleigh, M. R., additional, Bárczy, T., additional, Cameron, A. C., additional, Chamberlain, S., additional, Charnoz, S., additional, Cooke, B. F., additional, Corral Van Damme, C., additional, Correia, A. C. M., additional, Cristiani, S., additional, Damasso, M., additional, Davies, M. B., additional, Deleuil, M., additional, Demangeon, O. D. S., additional, Demory, B.-O., additional, Di Marcantonio, P., additional, Di Persio, G., additional, Dumusque, X., additional, Ehrenreich, D., additional, Erikson, A., additional, Figueira, P., additional, Fortier, A., additional, Fossati, L., additional, Fridlund, M., additional, Futyan, D., additional, Gandolfi, D., additional, García Muñoz, A., additional, Garcia, L. J., additional, Gill, S., additional, Gillen, E., additional, Gillon, M., additional, Goad, M. R., additional, González Hernández, J. I., additional, Guedel, M., additional, Günther, M. N., additional, Haldemann, J., additional, Henderson, B., additional, Heng, K., additional, Hogan, A. E., additional, Isaak, K., additional, Jehin, E., additional, Jenkins, J. S., additional, Jordán, A., additional, Kiss, L., additional, Kristiansen, M. H., additional, Lam, K., additional, Lavie, B., additional, Lecavelier des Etangs, A., additional, Lendl, M., additional, Lillo-Box, J., additional, Lo Curto, G., additional, Magrin, D., additional, Martins, C. J. A. P., additional, Maxted, P. F. L., additional, McCormac, J., additional, Mehner, A., additional, Micela, G., additional, Molaro, P., additional, Moyano, M., additional, Murray, C. A., additional, Nascimbeni, V., additional, Nunes, N. J., additional, Olofsson, G., additional, Osborn, H. P., additional, Oshagh, M., additional, Ottensamer, R., additional, Pagano, I., additional, Pallé, E., additional, Pedersen, P. P., additional, Pepe, F. A., additional, Persson, C. M., additional, Peter, G., additional, Piotto, G., additional, Polenta, G., additional, Pollacco, D., additional, Poretti, E., additional, Pozuelos, F. J., additional, Queloz, D., additional, Ragazzoni, R., additional, Rando, N., additional, Ratti, F., additional, Rauer, H., additional, Raynard, L., additional, Rebolo, R., additional, Reimers, C., additional, Ribas, I., additional, Santos, N. C., additional, Scandariato, G., additional, Schneider, J., additional, Sebastian, D., additional, Sestovic, M., additional, Simon, A. E., additional, Smith, A. M. S., additional, Sousa, S. G., additional, Sozzetti, A., additional, Steller, M., additional, Suárez Mascareño, A., additional, Szabó, Gy. M., additional, Ségransan, D., additional, Thomas, N., additional, Thompson, S., additional, Tilbrook, R. H., additional, Triaud, A., additional, Turner, O., additional, Udry, S., additional, Van Grootel, V., additional, Venus, H., additional, Verrecchia, F., additional, Vines, J. I., additional, Walton, N. A., additional, West, R. G., additional, Wheatley, P. J., additional, Wolter, D., additional, and Zapatero Osorio, M. R., additional

Published
2021
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225. Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops.

Author

Maxted, P F L, Ehrenreich, D, Wilson, T G, Alibert, Y, Cameron, A Collier, Hoyer, S, Sousa, S G, Olofsson, G, Bekkelien, A, Deline, A, Delrez, L, Bonfanti, A, Borsato, L, Alonso, R, Anglada Escudé, G, Barrado, D, Barros, S C C, Baumjohann, W, Beck, M, and Beck, T

Subjects
SPACE telescopes, INTEGRATED software, ORBITS (Astronomy), TELECOMMUNICATION satellites, PHOTOMETRY, EXTRASOLAR planets
Abstract

CHEOPS (CHaracterising ExOPlanet Satellite) is an ESA S-class mission that observes bright stars at high cadence from low-Earth orbit. The main aim of the mission is to characterize exoplanets that transit nearby stars using ultrahigh precision photometry. Here, we report the analysis of transits observed by CHEOPS during its Early Science observing programme for four well-known exoplanets: GJ 436 b, HD 106315 b, HD 97658 b, and GJ 1132 b. The analysis is done using pycheops , an open-source software package we have developed to easily and efficiently analyse CHEOPS light-curve data using state-of-the-art techniques that are fully described herein. We show that the precision of the transit parameters measured using CHEOPS is comparable to that from larger space telescopes such as Spitzer Space Telescope and Kepler. We use the updated planet parameters from our analysis to derive new constraints on the internal structure of these four exoplanets. [ABSTRACT FROM AUTHOR]

Published
2022
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226. Global Analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey

Author

Lienhard, F., Queloz, D., Gillon, M., Burdanov, A., Delrez, L., Ducrot, E., Handley, W., Jehin, E., Murray, C. A., Triaud, A. H. M. J., Gillen, E., Mortier, A., Rackham, B. V., Lienhard, F., Queloz, D., Gillon, M., Burdanov, A., Delrez, L., Ducrot, E., Handley, W., Jehin, E., Murray, C. A., Triaud, A. H. M. J., Gillen, E., Mortier, A., and Rackham, B. V.

Abstract

We conducted a global analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey - a prototype of the SPECULOOS transit search conducted with the TRAPPIST-South robotic telescope in Chile from 2011 to 2017 - to estimate the occurrence rate of close-in planets such as TRAPPIST-1b orbiting ultra-cool dwarfs. For this purpose, the photometric data of 40 nearby ultra-cool dwarfs were reanalysed in a self-consistent and fully automated manner starting from the raw images. The pipeline developed specifically for this task generates differential light curves, removes non-planetary photometric features and stellar variability, and searches for transits. It identifies the transits of TRAPPIST-1b and TRAPPIST-1c without any human intervention. To test the pipeline and the potential output of similar surveys, we injected planetary transits into the light curves on a star-by-star basis and tested whether the pipeline is able to detect them. The achieved photometric precision enables us to identify Earth-sized planets orbiting ultra-cool dwarfs as validated by the injection tests. Our planet-injection simulation further suggests a lower limit of 10 per cent on the occurrence rate of planets similar to TRAPPIST-1b with a radius between 1 and 1.3 $R_\oplus$ and the orbital period between 1.4 and 1.8 days., Comment: Accepted for publication in MNRAS, 21 pages, 18 figures, 3 tables

Published
2020
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227. Two transiting hot Jupiters from the WASP survey: WASP-150b and WASP-176b

Author

Cooke, Benjamin F., Pollacco, Don, Almleaky, Y., Barkaoui, K., Benkhaldoun, Z., Blake, James A., Bouchy, François, Boumis, Panos, Brown, D. J. A., Bruni, Ivan, Burdanov, A., Cameron, Andrew Collier, Chote, Paul, Daassou, A., D'ago, Giuseppe, Dalal, Shweta, Damasso, Mario, Delrez, L., Doyle, A. P., Ducrot, E., Gillon, M., Hébrard, G., Hellier, C., Henning, Thomas, Jehin, E., Kiefer, Flavien, King, George W., Liakos, Alexios, Lopez, Théo, Mancini, Luigi, Mardling, Rosemary, Maxted, P. F. L., McCormac, James, Murray, C., Nielsen, Louise D., Osborn, Hugh, Palle, E., Pepe, Francesco, Pozuelos, F. J., Prieto-Arranz, J., Queloz, D., Schanche, Nicole, Ségransan, Damien, Smalley, Barry, Southworth, John, Thompson, S., Turner, Oliver, Udry, Stéphane, Velasco, S., West, Richard, Wheatley, Pete, Alikakos, John, Cooke, Benjamin F., Pollacco, Don, Almleaky, Y., Barkaoui, K., Benkhaldoun, Z., Blake, James A., Bouchy, François, Boumis, Panos, Brown, D. J. A., Bruni, Ivan, Burdanov, A., Cameron, Andrew Collier, Chote, Paul, Daassou, A., D'ago, Giuseppe, Dalal, Shweta, Damasso, Mario, Delrez, L., Doyle, A. P., Ducrot, E., Gillon, M., Hébrard, G., Hellier, C., Henning, Thomas, Jehin, E., Kiefer, Flavien, King, George W., Liakos, Alexios, Lopez, Théo, Mancini, Luigi, Mardling, Rosemary, Maxted, P. F. L., McCormac, James, Murray, C., Nielsen, Louise D., Osborn, Hugh, Palle, E., Pepe, Francesco, Pozuelos, F. J., Prieto-Arranz, J., Queloz, D., Schanche, Nicole, Ségransan, Damien, Smalley, Barry, Southworth, John, Thompson, S., Turner, Oliver, Udry, Stéphane, Velasco, S., West, Richard, Wheatley, Pete, and Alikakos, John

Abstract

We report the discovery of two transiting exoplanets from the WASP survey, WASP-150b and WASP-176b. WASP-150b is an eccentric ($e$ = 0.38) hot Jupiter on a 5.6 day orbit around a $V$ = 12.03, F8 main-sequence host. The host star has a mass and radius of 1.4 $\rm M_{\odot}$ and 1.7 $\rm R_{\odot}$ respectively. WASP-150b has a mass and radius of 8.5 $\rm M_J$ and 1.1 $\rm R_J$, leading to a large planetary bulk density of 6.4 $\rm \rho_J$. WASP-150b is found to be $\sim3$ Gyr old, well below its circularisation timescale, supporting the eccentric nature of the planet. WASP-176b is a hot Jupiter planet on a 3.9 day orbit around a $V$ = 12.01, F9 sub-giant host. The host star has a mass and radius of 1.3 $\rm M_{\odot}$ and 1.9 $\rm R_{\odot}$. WASP-176b has a mass and radius of 0.86 $\rm M_J$ and 1.5 $\rm R_J$ respectively, leading to a planetary bulk density of 0.23 $\rm \rho_J$., Comment: 15 pages, 14 figures. Accepted for publication in The Astronomical Journal

Published
2020
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228. Photometry and Performance of SPECULOOS-South

Author

Murray, C. A., Delrez, L., Pedersen, P. P., Queloz, D., Gillon, M., Burdanov, A., Ducrot, E., Garcia, L. J., Lienhard, F., Demory, B. O., Jehin, E., McCormac, J., Sebastian, D., Sohy, S., Thompson, S. J., Triaud, A. H. M. J., Grootel, V. V., Günther, M. N., Huang, C. X., Murray, C. A., Delrez, L., Pedersen, P. P., Queloz, D., Gillon, M., Burdanov, A., Ducrot, E., Garcia, L. J., Lienhard, F., Demory, B. O., Jehin, E., McCormac, J., Sebastian, D., Sohy, S., Thompson, S. J., Triaud, A. H. M. J., Grootel, V. V., Günther, M. N., and Huang, C. X.

Abstract

SPECULOOS-South, an observatory composed of four independent 1m robotic telescopes, located at ESO Paranal, Chile, started scientific operation in January 2019. This Southern Hemisphere facility operates as part of SPECULOOS, an international network of 1m-class telescopes surveying for transiting terrestrial planets around the nearest and brightest ultra-cool dwarfs. To automatically and efficiently process the observations of SPECULOOS-South, and to deal with the specialised photometric requirements of ultra-cool dwarf targets, we present our automatic pipeline. This pipeline includes an algorithm for automated differential photometry and an extensive correction technique for the effects of telluric water vapour, using ground measurements of the precipitable water vapour. Observing very red targets in the near-infrared can result in photometric systematics in the differential lightcurves, related to the temporally-varying, wavelength-dependent opacity of the Earth's atmosphere. These systematics are sufficient to affect the daily quality of the lightcurves, the longer time-scale variability study of our targets and even mimic transit-like signals. Here we present the implementation and impact of our water vapour correction method. Using the 179 nights and 98 targets observed in the I+z' filter by SPECULOOS-South since January 2019, we show the impressive photometric performance of the facility (with a median precision of ~1.5 mmag for 30-min binning of the raw, non-detrended lightcurves) and assess its detection potential. We compare simultaneous observations with SPECULOOS-South and TESS, to show that we readily achieve high-precision, space-level photometry for bright, ultra-cool dwarfs, highlighting SPECULOOS-South as the first facility of its kind., Comment: Accepted for publication in MNRAS, 13 pages, 12 figures, 1 table

Published
2020
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229. TRAPPIST-1: Global Results of the Spitzer Exploration Science Program {\it Red Worlds}

Author

Ducrot, Elsa, Gillon, M., Delrez, L., Agol, E., Rimmer, P., Turbet, M., Günther, M. N., Demory, B-O., Triaud, A. H. M. J., Bolmont, E., Burgasser, A., Carey, S. J., Ingalls, J. G., Jehin, E., Leconte, J., Lederer, S. M., Queloz, D., Raymond, S. N., Selsis, F., Van Grootel, V., de Wit, J., Ducrot, Elsa, Gillon, M., Delrez, L., Agol, E., Rimmer, P., Turbet, M., Günther, M. N., Demory, B-O., Triaud, A. H. M. J., Bolmont, E., Burgasser, A., Carey, S. J., Ingalls, J. G., Jehin, E., Leconte, J., Lederer, S. M., Queloz, D., Raymond, S. N., Selsis, F., Van Grootel, V., and de Wit, J.

Abstract

With more than 1000 hours of observation from Feb 2016 to Oct 2019, the Spitzer Exploration Program Red Worlds (ID: 13067, 13175 and 14223) exclusively targeted TRAPPIST-1, a nearby (12pc) ultracool dwarf star orbited by seven transiting Earth-sized planets, all well-suited for a detailed atmospheric characterization with the upcoming JWST. In this paper, we present the global results of the project. We analyzed 88 new transits and combined them with 100 previously analyzed transits, for a total of 188 transits observed at 3.6 or 4.5 $\mu$m. We also analyzed 29 occultations (secondary eclipses) of planet b and eight occultations of planet c observed at 4.5 $\mu$m to constrain the brightness temperatures of their daysides. We identify several orphan transit-like structures in our Spitzer photometry, but all of them are of low significance. We do not confirm any new transiting planets. We estimate for TRAPPIST-1 transit depth measurements mean noise floors of $\sim$35 and 25 ppm in channels 1 and 2 of Spitzer/IRAC, respectively. most of this noise floor is of instrumental origins and due to the large inter-pixel inhomogeneity of IRAC InSb arrays, and that the much better interpixel homogeneity of JWST instruments should result in noise floors as low as 10ppm, which is low enough to enable the atmospheric characterization of the planets by transit transmission spectroscopy. We construct updated broadband transmission spectra for all seven planets which show consistent transit depths between the two Spitzer channels. We identify and model five distinct high energy flares in the whole dataset, and discuss our results in the context of habitability. Finally, we fail to detect occultation signals of planets b and c at 4.5 $\mu$m, and can only set 3$\sigma$ upper limits on their dayside brightness temperatures (611K for b 586K for c)., Comment: 50 pages, 21 figures. Accepted for publication in Astronomy and Astrophysics

Published
2020
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230. SPECULOOS -- Ultracool Dwarf Transit Survey: Target List and Strategy

Author

Sebastian, D., Gillon, M., Ducrot, E., Pozuelos, F. J., Garcia, L. J., Günther, M. N., Delrez, L., Queloz, D., Demory, B. O., Triaud, A. H. M. J., Burgasser, A., de Wit, J., Burdanov, A., Dransfield, G., Jehin, E., McCormac, J., Murray, C. A., Niraula, P., Pedersen, P. P., Rackham, B. V., Sohy, S., Thompson, S., Van Grootel, V., Sebastian, D., Gillon, M., Ducrot, E., Pozuelos, F. J., Garcia, L. J., Günther, M. N., Delrez, L., Queloz, D., Demory, B. O., Triaud, A. H. M. J., Burgasser, A., de Wit, J., Burdanov, A., Dransfield, G., Jehin, E., McCormac, J., Murray, C. A., Niraula, P., Pedersen, P. P., Rackham, B. V., Sohy, S., Thompson, S., and Van Grootel, V.

Abstract

One of the most promising avenues for the detailed study of temperate Earth-sized exoplanets is the detection of such planets in transit in front of stars small and nearby enough to make possible their thorough atmospheric characterisation with next generation telescopes like the James Webb Space telescope (JWST) or Extremely Large Telescope (ELT). In this context, the TRAPPIST-1 planets form an unique benchmark system that has gathered the interest of a large scientific community. The SPECULOOS survey is an exoplanet transit survey, that targets a volume-limited (40 pc) sample of ultracool dwarf stars. We define the SPECULOOS target list as the sum of three non-overlapping sub-programs incorporating the latest type objects (T_eff < 3000K): Program1: 365 dwarfs that are small and nearby enough to make possible the detailed atmospheric characterisation of an `Earth-like' planet with the upcoming JWST, Program2: 171 dwarfs of M5-type and later for which a significant detection of a planet similar to TRAPPIST-1b should be within reach of the exoplanet transit survey TESS, and Program3: 1121 dwarfs later than M6-type that aims to perform a statistical census of short-period planets around ultracool dwarf stars. Our compound target list includes 1657 photometrically classified late-type dwarfs. 260 of these targets are classified for the first time as possible nearby ultracool dwarf stars. Our general observational strategy is to monitor each target for 100 to 200hr with our telescope network, by efficiently using the synergy with TESS for our Program2 and a fraction of the targets of Program1. We expect to detect up to a few dozens temperate, rocky planets, a handful of them being amenable for atmospheric characterisation with JWST and other future giant telescopes which will improve drastically our understanding of the planetary population of the latest-type stars., Comment: Accepted for publication in A&A, 13pages, 10 figures

Published
2020
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231. The hot dayside and asymmetric transit of WASP-189b seen by CHEOPS

Author

Lendl, M., Csizmadia, Sz., Deline, A., Fossati, L., Kitzmann, D., Heng, K., Hoyer, S., Salmon, S., Benz, W., Broeg, C., Ehrenreich, D., Fortier, A., Queloz, D., Bonfanti, A., Brandeker, A., Cameron, A. Collier, Delrez, L., Muñoz, A. Garcia, Hooton, M. J., Maxted, P. F. L., Morris, B. M., Van Grootel, V., Wilson, T. G., Alibert, Y., Alonso, R., Asquier, J., Bárczy, T. Bandy T., Barrado, D., Barros, S. C. C, Baumjohann, W., Beck, M., Beck, T., Bekkelien, A., Bergomi, M., Billot, N., Biondi, F., Bonfils, X., Bourrier, V., Busch, M-D., Cabrera, J., Cessa, V., Charnoz, S., Chazelas, B., Van Damme, C. Corral, Davies, M. B., Deleuil, M., Demangeon, O. D. S, Demory, B. -O., Erikson, A., Farinato, J., Fridlund, M., Futyan, D., Gandolfi, D., Gillon, M., Guterman, P., Hasiba, J., Hernandez, E., Isaak, K. G., Kiss, L., Kuntzer, T., Etangs, A. Lecavelier des, Lüftinger, T., Laskar, J., Lovis, C., Magrin, D., Malvasio, L., Marafatto, L., Michaelis, H., Munari, M., Nascimbeni, V., Olofsson, G., Ottacher, H., Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piazza, D., Piotto, G., Pollacco, D., Ratti, F., Rauer, H., Ragazzoni, R., Rando, N., Ribas, I., Rieder, M., Rohlfs, R., Safa, F., Santos, N. C., Scandariato, G., Ségransan, D., Simon, A. E., Singh, V., Smith, A. M. S., Sordet, M., Sousa, S. G., Steller, M., Szabó, Gy. M., Thomas, N., Tschentscher, M., Udry, S., Viotto, V., Walter, I., Walton, N. A., Wildi, F., Wolter, D., Lendl, M., Csizmadia, Sz., Deline, A., Fossati, L., Kitzmann, D., Heng, K., Hoyer, S., Salmon, S., Benz, W., Broeg, C., Ehrenreich, D., Fortier, A., Queloz, D., Bonfanti, A., Brandeker, A., Cameron, A. Collier, Delrez, L., Muñoz, A. Garcia, Hooton, M. J., Maxted, P. F. L., Morris, B. M., Van Grootel, V., Wilson, T. G., Alibert, Y., Alonso, R., Asquier, J., Bárczy, T. Bandy T., Barrado, D., Barros, S. C. C, Baumjohann, W., Beck, M., Beck, T., Bekkelien, A., Bergomi, M., Billot, N., Biondi, F., Bonfils, X., Bourrier, V., Busch, M-D., Cabrera, J., Cessa, V., Charnoz, S., Chazelas, B., Van Damme, C. Corral, Davies, M. B., Deleuil, M., Demangeon, O. D. S, Demory, B. -O., Erikson, A., Farinato, J., Fridlund, M., Futyan, D., Gandolfi, D., Gillon, M., Guterman, P., Hasiba, J., Hernandez, E., Isaak, K. G., Kiss, L., Kuntzer, T., Etangs, A. Lecavelier des, Lüftinger, T., Laskar, J., Lovis, C., Magrin, D., Malvasio, L., Marafatto, L., Michaelis, H., Munari, M., Nascimbeni, V., Olofsson, G., Ottacher, H., Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piazza, D., Piotto, G., Pollacco, D., Ratti, F., Rauer, H., Ragazzoni, R., Rando, N., Ribas, I., Rieder, M., Rohlfs, R., Safa, F., Santos, N. C., Scandariato, G., Ségransan, D., Simon, A. E., Singh, V., Smith, A. M. S., Sordet, M., Sousa, S. G., Steller, M., Szabó, Gy. M., Thomas, N., Tschentscher, M., Udry, S., Viotto, V., Walter, I., Walton, N. A., Wildi, F., and Wolter, D.

Abstract

The CHEOPS space mission dedicated to exoplanet follow-up was launched in December 2019, equipped with the capacity to perform photometric measurements at the 20 ppm level. As CHEOPS carries out its observations in a broad optical passband, it can provide insights into the reflected light from exoplanets and constrain the short-wavelength thermal emission for the hottest of planets by observing occultations and phase curves. Here, we report the first CHEOPS observation of an occultation, namely, that of the hot Jupiter WASP-189b, a $M_P \approx 2 M_J$ planet orbiting an A-type star. We detected the occultation of WASP-189 b at high significance in individual measurements and derived an occultation depth of $dF = 87.9 \pm 4.3$ppm based on four occultations. We compared these measurements to model predictions and we find that they are consistent with an unreflective atmosphere heated to a temperature of $3435 \pm 27$K, when assuming inefficient heat redistribution. Furthermore, we present two transits of WASP-189b observed by CHEOPS. These transits have an asymmetric shape that we attribute to gravity darkening of the host star caused by its high rotation rate. We used these measurements to refine the planetary parameters, finding a $\sim25\%$ deeper transit compared to the discovery paper and updating the radius of WASP-189b to $1.619\pm0.021 R_J$. We further measured the projected orbital obliquity to be $\lambda = 86.4^{+2.9}_{-4.4}$deg, a value that is in good agreement with a previous measurement from spectroscopic observations, and derived a true obliquity of $\Psi = 85.4\pm4.3$deg. Finally, we provide reference values for the photometric precision attained by the CHEOPS satellite: for the V=6.6 mag star, and using a one-hour binning, we obtain a residual RMS between 10 and 17ppm on the individual light curves, and 5.7ppm when combining the four visits., Comment: In press at Astronomy and Astrophysics

Published
2020
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232. CHEOPS observations of the HD 108236 planetary system: a fifth planet, improved ephemerides, and planetary radii

Author

Bonfanti, A., primary, Delrez, L., additional, Hooton, M. J., additional, Wilson, T. G., additional, Fossati, L., additional, Alibert, Y., additional, Hoyer, S., additional, Mustill, A. J., additional, Osborn, H. P., additional, Adibekyan, V., additional, Gandolfi, D., additional, Salmon, S., additional, Sousa, S. G., additional, Tuson, A., additional, Van Grootel, V., additional, Cabrera, J., additional, Nascimbeni, V., additional, Maxted, P. F. L., additional, Barros, S. C. C., additional, Billot, N., additional, Bonfils, X., additional, Borsato, L., additional, Broeg, C., additional, Davies, M. B., additional, Deleuil, M., additional, Demangeon, O. D. S., additional, Fridlund, M., additional, Lacedelli, G., additional, Lendl, M., additional, Persson, C., additional, Santos, N. C., additional, Scandariato, G., additional, Szabó, Gy. M., additional, Collier Cameron, A., additional, Udry, S., additional, Benz, W., additional, Beck, M., additional, Ehrenreich, D., additional, Fortier, A., additional, Isaak, K. G., additional, Queloz, D., additional, Alonso, R., additional, Asquier, J., additional, Bandy, T., additional, Bárczy, T., additional, Barrado, D., additional, Barragán, O., additional, Baumjohann, W., additional, Beck, T., additional, Bekkelien, A., additional, Bergomi, M., additional, Brandeker, A., additional, Busch, M.-D., additional, Cessa, V., additional, Charnoz, S., additional, Chazelas, B., additional, Corral Van Damme, C., additional, Demory, B.-O., additional, Erikson, A., additional, Farinato, J., additional, Futyan, D., additional, Garcia Muñoz, A., additional, Gillon, M., additional, Guedel, M., additional, Guterman, P., additional, Hasiba, J., additional, Heng, K., additional, Hernandez, E., additional, Kiss, L., additional, Kuntzer, T., additional, Laskar, J., additional, Lecavelier des Etangs, A., additional, Lovis, C., additional, Magrin, D., additional, Malvasio, L., additional, Marafatto, L., additional, Michaelis, H., additional, Munari, M., additional, Olofsson, G., additional, Ottacher, H., additional, Ottensamer, R., additional, Pagano, I., additional, Pallé, E., additional, Peter, G., additional, Piazza, D., additional, Piotto, G., additional, Pollacco, D., additional, Ragazzoni, R., additional, Rando, N., additional, Ratti, F., additional, Rauer, H., additional, Ribas, I., additional, Rieder, M., additional, Rohlfs, R., additional, Safa, F., additional, Salatti, M., additional, Ségransan, D., additional, Simon, A. E., additional, Smith, A. M. S., additional, Sordet, M., additional, Steller, M., additional, Thomas, N., additional, Tschentscher, M., additional, Van Eylen, V., additional, Viotto, V., additional, Walter, I., additional, Walton, N. A., additional, Wildi, F., additional, and Wolter, D., additional

Published
2021
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233. SPECULOOS: Ultracool dwarf transit survey

Author

Sebastian, D., primary, Gillon, M., additional, Ducrot, E., additional, Pozuelos, F. J., additional, Garcia, L. J., additional, Günther, M. N., additional, Delrez, L., additional, Queloz, D., additional, Demory, B. O., additional, Triaud, A. H. M. J., additional, Burgasser, A., additional, de Wit, J., additional, Burdanov, A., additional, Dransfield, G., additional, Jehin, E., additional, McCormac, J., additional, Murray, C. A., additional, Niraula, P., additional, Pedersen, P. P., additional, Rackham, B. V., additional, Sohy, S., additional, Thompson, S., additional, and Van Grootel, V., additional

Published
2021
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234. study of flares in the ultra-cool regime from SPECULOOS-South.

Author

Murray, C A, Queloz, D, Gillon, M, Demory, B O, Triaud, A H M J, de Wit, J, Burdanov, A, Chinchilla, P, Delrez, L, Dransfield, G, Ducrot, E, Garcia, L J, Gómez Maqueo Chew, Y, Günther, M N, Jehin, E, McCormac, J, Niraula, P, Pedersen, P P, Pozuelos, F J, and Rackham, B V

Subjects
PLANETARY orbits, SOLAR flares, STELLAR rotation, ORIGIN of life, STELLAR orbits
Abstract

We present a study of photometric flares on 154 low-mass (≤0.2 M⊙) objects observed by the SPECULOOS-South Observatory from 2018 June 1 to 2020 March 23. In this sample, we identify 85 flaring objects, ranging in spectral type from M4 to L0. We detect 234 flares in this sample, with energies between 1029.2 and 1032.7 erg, using both automated and manual methods. With this work, we present the largest photometric sample of flares on late-M and ultra-cool dwarfs to date. By extending previous M dwarf flare studies into the ultra-cool regime, we find M5–M7 stars are more likely to flare than both earlier, and later, M dwarfs. By performing artificial flare injection-recovery tests, we demonstrate that we can detect a significant proportion of flares down to an amplitude of 1 per cent, and we are most sensitive to flares on the coolest stars. Our results reveal an absence of high-energy flares on the reddest dwarfs. To probe the relations between rotation and activity for fully convective stars, we extract rotation periods for fast rotators and lower-bound period estimates of slow rotators. These rotation periods span from 2.2 h to 65 d, and we find that the proportion of flaring stars increases for the most fastest rotators. Finally, we discuss the impact of our flare sample on planets orbiting ultra-cool stars. As stars become cooler, they flare less frequently; therefore, it is unlikely that planets around the most reddest dwarfs would enter the 'abiogenesis' zone or drive visible-light photosynthesis through flares alone. [ABSTRACT FROM AUTHOR]

Published
2022
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235. The CHEOPS mission

Author

Benz, W., primary, Broeg, C., additional, Fortier, A., additional, Rando, N., additional, Beck, T., additional, Beck, M., additional, Queloz, D., additional, Ehrenreich, D., additional, Maxted, P. F. L., additional, Isaak, K. G., additional, Billot, N., additional, Alibert, Y., additional, Alonso, R., additional, António, C., additional, Asquier, J., additional, Bandy, T., additional, Bárczy, T., additional, Barrado, D., additional, Barros, S. C. C., additional, Baumjohann, W., additional, Bekkelien, A., additional, Bergomi, M., additional, Biondi, F., additional, Bonfils, X., additional, Borsato, L., additional, Brandeker, A., additional, Busch, M.-D., additional, Cabrera, J., additional, Cessa, V., additional, Charnoz, S., additional, Chazelas, B., additional, Collier Cameron, A., additional, Corral Van Damme, C., additional, Cortes, D., additional, Davies, M. B., additional, Deleuil, M., additional, Deline, A., additional, Delrez, L., additional, Demangeon, O., additional, Demory, B. O., additional, Erikson, A., additional, Farinato, J., additional, Fossati, L., additional, Fridlund, M., additional, Futyan, D., additional, Gandolfi, D., additional, Garcia Munoz, A., additional, Gillon, M., additional, Guterman, P., additional, Gutierrez, A., additional, Hasiba, J., additional, Heng, K., additional, Hernandez, E., additional, Hoyer, S., additional, Kiss, L. L., additional, Kovacs, Z., additional, Kuntzer, T., additional, Laskar, J., additional, Lecavelier des Etangs, A., additional, Lendl, M., additional, López, A., additional, Lora, I., additional, Lovis, C., additional, Lüftinger, T., additional, Magrin, D., additional, Malvasio, L., additional, Marafatto, L., additional, Michaelis, H., additional, de Miguel, D., additional, Modrego, D., additional, Munari, M., additional, Nascimbeni, V., additional, Olofsson, G., additional, Ottacher, H., additional, Ottensamer, R., additional, Pagano, I., additional, Palacios, R., additional, Pallé, E., additional, Peter, G., additional, Piazza, D., additional, Piotto, G., additional, Pizarro, A., additional, Pollaco, D., additional, Ragazzoni, R., additional, Ratti, F., additional, Rauer, H., additional, Ribas, I., additional, Rieder, M., additional, Rohlfs, R., additional, Safa, F., additional, Salatti, M., additional, Santos, N. C., additional, Scandariato, G., additional, Ségransan, D., additional, Simon, A. E., additional, Smith, A. M. S., additional, Sordet, M., additional, Sousa, S. G., additional, Steller, M., additional, Szabó, G. M., additional, Szoke, J., additional, Thomas, N., additional, Tschentscher, M., additional, Udry, S., additional, Van Grootel, V., additional, Viotto, V., additional, Walter, I., additional, Walton, N. A., additional, Wildi, F., additional, and Wolter, D., additional

Published
2020
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236. The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS

Author

Lendl, M., primary, Csizmadia, Sz., additional, Deline, A., additional, Fossati, L., additional, Kitzmann, D., additional, Heng, K., additional, Hoyer, S., additional, Salmon, S., additional, Benz, W., additional, Broeg, C., additional, Ehrenreich, D., additional, Fortier, A., additional, Queloz, D., additional, Bonfanti, A., additional, Brandeker, A., additional, Collier Cameron, A., additional, Delrez, L., additional, Garcia Muñoz, A., additional, Hooton, M. J., additional, Maxted, P. F. L., additional, Morris, B. M., additional, Van Grootel, V., additional, Wilson, T. G., additional, Alibert, Y., additional, Alonso, R., additional, Asquier, J., additional, Bandy, T., additional, Bárczy, T., additional, Barrado, D., additional, Barros, S. C. C., additional, Baumjohann, W., additional, Beck, M., additional, Beck, T., additional, Bekkelien, A., additional, Bergomi, M., additional, Billot, N., additional, Biondi, F., additional, Bonfils, X., additional, Bourrier, V., additional, Busch, M.-D., additional, Cabrera, J., additional, Cessa, V., additional, Charnoz, S., additional, Chazelas, B., additional, Corral Van Damme, C., additional, Davies, M. B., additional, Deleuil, M., additional, Demangeon, O. D. S., additional, Demory, B.-O., additional, Erikson, A., additional, Farinato, J., additional, Fridlund, M., additional, Futyan, D., additional, Gandolfi, D., additional, Gillon, M., additional, Guterman, P., additional, Hasiba, J., additional, Hernandez, E., additional, Isaak, K. G., additional, Kiss, L., additional, Kuntzer, T., additional, Lecavelier des Etangs, A., additional, Lüftinger, T., additional, Laskar, J., additional, Lovis, C., additional, Magrin, D., additional, Malvasio, L., additional, Marafatto, L., additional, Michaelis, H., additional, Munari, M., additional, Nascimbeni, V., additional, Olofsson, G., additional, Ottacher, H., additional, Ottensamer, R., additional, Pagano, I., additional, Pallé, E., additional, Peter, G., additional, Piazza, D., additional, Piotto, G., additional, Pollacco, D., additional, Ratti, F., additional, Rauer, H., additional, Ragazzoni, R., additional, Rando, N., additional, Ribas, I., additional, Rieder, M., additional, Rohlfs, R., additional, Safa, F., additional, Santos, N. C., additional, Scandariato, G., additional, Ségransan, D., additional, Simon, A. E., additional, Singh, V., additional, Smith, A. M. S., additional, Sordet, M., additional, Sousa, S. G., additional, Steller, M., additional, Szabó, Gy. M., additional, Thomas, N., additional, Tschentscher, M., additional, Udry, S., additional, Viotto, V., additional, Walter, I., additional, Walton, N. A., additional, Wildi, F., additional, and Wolter, D., additional

Published
2020
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237. TRAPPIST-1: Global results of the Spitzer Exploration Science Program Red Worlds

Author

Ducrot, E., primary, Gillon, M., additional, Delrez, L., additional, Agol, E., additional, Rimmer, P., additional, Turbet, M., additional, Günther, M. N., additional, Demory, B.-O., additional, Triaud, A. H. M. J., additional, Bolmont, E., additional, Burgasser, A., additional, Carey, S. J., additional, Ingalls, J. G., additional, Jehin, E., additional, Leconte, J., additional, Lederer, S. M., additional, Queloz, D., additional, Raymond, S. N., additional, Selsis, F., additional, Van Grootel, V., additional, and de Wit, J., additional

Published
2020
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238. Global analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey

Author

Lienhard, F, primary, Queloz, D, additional, Gillon, M, additional, Burdanov, A, additional, Delrez, L, additional, Ducrot, E, additional, Handley, W, additional, Jehin, E, additional, Murray, C A, additional, Triaud, A H M J, additional, Gillen, E, additional, Mortier, A, additional, and Rackham, B V, additional

Published
2020
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239. Photometry and performance of SPECULOOS-South

Author

Murray, C A, primary, Delrez, L, primary, Pedersen, P P, primary, Queloz, D, primary, Gillon, M, primary, Burdanov, A, primary, Ducrot, E, primary, Garcia, L J, primary, Lienhard, F, primary, Demory, B O, primary, Jehin, E, primary, McCormac, J, primary, Sebastian, D, primary, Sohy, S, primary, Thompson, S J, primary, Triaud, A H M J, primary, Grootel, V V, primary, Günther, M N, primary, and Huang, C X, primary

Published
2020
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240. Two Transiting Hot Jupiters from the WASP Survey: WASP-150b and WASP-176b

Author

Cooke, Benjamin F., primary, Pollacco, Don, additional, Almleaky, Y., additional, Barkaoui, K., additional, Benkhaldoun, Z., additional, Blake, James A., additional, Bouchy, François, additional, Boumis, Panos, additional, Brown, D. J. A., additional, Bruni, Ivan, additional, Burdanov, A., additional, Cameron, Andrew Collier, additional, Chote, Paul, additional, Daassou, A., additional, D’ago, Giuseppe, additional, Dalal, Shweta, additional, Damasso, Mario, additional, Delrez, L., additional, Doyle, A. P., additional, Ducrot, E., additional, Gillon, M., additional, Hébrard, G., additional, Hellier, C., additional, Henning, Thomas, additional, Jehin, E., additional, Kiefer, Flavien, additional, King, George W., additional, Liakos, Alexios, additional, Lopez, Théo, additional, Mancini, Luigi, additional, Mardling, Rosemary, additional, Maxted, P. F. L., additional, McCormac, James, additional, Murray, C., additional, Nielsen, Louise D., additional, Osborn, Hugh, additional, Palle, E., additional, Pepe, Francesco, additional, Pozuelos, F. J., additional, Prieto-Arranz, J., additional, Queloz, D., additional, Schanche, Nicole, additional, Ségransan, Damien, additional, Smalley, Barry, additional, Southworth, John, additional, Thompson, S., additional, Turner, Oliver, additional, Udry, Stéphane, additional, Velasco, S., additional, West, Richard, additional, Wheatley, Pete, additional, and Alikakos, John, additional

Published
2020
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241. Searching for transiting cold Jupiters around bright stars with ASTEP South at Dome C, Antarctica

Author

Crouzet, N., Mékarnia, D., Guillot, T., Bayliss, D., Deeg, H., Palle, E., Abe, L., Agabi, A., Rivet, J., Murgas, F., Gillon, M., Delrez, L., Jehin, E., and Espinoza, N.

Subjects
Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

Much of our understanding of gas giant exoplanets come from those transiting in front of bright stars at small orbital separations (P 3 days, a 0.05 au). These hot Jupiters are coupled to their host star: stellar irradiation impacts the chemistry and temperature structure of their atmospheres and tidal interactions affects the orbital dynamics and may even impact the star itself. In contrast, gas giant exoplanets with long orbital periods and large separations (P > 30 days, a > 0.2 au) are much less coupled to their host star and provide ideal benchmarks to study gas giant planets in general. However, only a few transiting "cold Jupiters" orbiting bright stars are known to date. In the past years, we conducted the ASTEP experiment (Antarctica Search for Transiting ExoPlanets) to search and characterize transiting exoplanets from Dome C, Antarctica and to qualify this site for photometry in the visible. One instrument, ASTEP South, is a 10 cm diameter lens equipped with a CCD camera in a thermalised box pointing continuously towards the celestial South pole. We analysed four winters of data collected with this instrument and identified about 30 transit candidates around relatively bright stars (9 < V < 13) with orbital periods up to 80 days. We performed photometric follow-up with the Las Cumbres Observatory (LCO) 0.4m telescopes to investigate these signals. Most of these stars are also observed by TESS and their lightcurves can be extracted from the full frame images. In this poster, we present our set of candidates, the first results of the photometric follow-up, and discuss the use of TESS data to investigate these objects.

Published
2019

242. WASP-South hot Jupiters: WASP-178b, WASP-184b, WASP-185b & WASP-192b

Author

Hellier, C., Anderson, D. R., Barkaoui, K., Benkhaldoun, Z., Bouchy, F., Burdanov, A., Cameron, A. Collier, Delrez, L., Gillon, M., Jehin, E., Nielsen, L. D., Maxted, P. F. L., Pepe, F., Pollacco, D., Pozuelos, F. J., Queloz, D., Segransan, D., Smalley, B., Triaud, A. H. M. J., Turner, O. D., Udry, S., West, R. G., Hellier, C., Anderson, D. R., Barkaoui, K., Benkhaldoun, Z., Bouchy, F., Burdanov, A., Cameron, A. Collier, Delrez, L., Gillon, M., Jehin, E., Nielsen, L. D., Maxted, P. F. L., Pepe, F., Pollacco, D., Pozuelos, F. J., Queloz, D., Segransan, D., Smalley, B., Triaud, A. H. M. J., Turner, O. D., Udry, S., and West, R. G.

Abstract

We report on four new transiting hot Jupiters discovered by the WASP-South survey. WASP-178b transits a V = 9.9, A1V star with Teff = 9350 +/- 150 K, the second-hottest transit host known. It has a highly bloated radius of 1.81 +/- 0.09 Rjup, in line with the known correlation between high irradiation and large size. With an estimated temperature of 2470 +/- 60 K, the planet is one of the best targets for studying ultra-hot Jupiters that is visible from the Southern hemisphere. The three host stars WASP-184, WASP-185 and WASP-192 are all post-main-sequence G0 stars of ages 4-8 Gyr. The larger stellar radii (1.3-1.7 Msun) mean that the transits are relatively shallow (0.7-0.9%) even though the planets have moderately inflated radii of 1.2-1.3 Rjup. WASP-185b has an eccentric orbit (e = 0.24) and a relatively long orbital period of 9.4 d. A star that is 4.6 arcsec from WASP-185 and 4.4 mag fainter might be physically associated., Comment: Version as Accepted for MNRAS (RV table added)

Published
2019
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243. WASP-169, WASP-171, WASP-175 and WASP-182: three hot Jupiters and one bloated sub-Saturn mass planet discovered by WASP-south

Author

Nielsen, L. D., Bouchy, F., Turner, O. D., Anderson, D. R., Barkaoui, K., Benkhaldoun, Z., Burdanov, A., Cameron, A. Collier, Delrez, L., Gillon, M., Ducrot, E., Hellier, C., Jehin, E., Lendl, M., Maxted, P. F. L., Pepe, F., Pollacco, D., Pozuelos, F. J., Queloz, D., Segransan, D., Smalley, B., Triaud, A. H. M. J., Udry, S., West, R. G., Nielsen, L. D., Bouchy, F., Turner, O. D., Anderson, D. R., Barkaoui, K., Benkhaldoun, Z., Burdanov, A., Cameron, A. Collier, Delrez, L., Gillon, M., Ducrot, E., Hellier, C., Jehin, E., Lendl, M., Maxted, P. F. L., Pepe, F., Pollacco, D., Pozuelos, F. J., Queloz, D., Segransan, D., Smalley, B., Triaud, A. H. M. J., Udry, S., and West, R. G.

Abstract

We present the discovery of four new giant planets from \WASP, three hot Jupiters and one bloated sub-Saturn mass planet; WASP-169b, WASP-171b, WASP-175b and WASP-182b. Besides the discovery photometry from \wasp\ we use radial velocity measurements from CORALIE and HARPS as well as follow-up photometry from EulerCam, TRAPPIST-North and -South and SPECULOOS. WASP-169b is a low density Jupiter ($M=0.561 \pm 0.061~\mathrm{M_{Jup}}, R=1.304^{+0.150}_{-0.073} ~\mathrm{R_{Jup}}$) orbiting a V=12.17 F8 sub-giant in a 5.611~day orbit. WASP-171b is a typical hot Jupiter ($M=1.084 \pm 0.094~\mathrm{M_{Jup}}, R=0.98^{+0.07}_{-0.04} ~\mathrm{R_{Jup}}$, $P=3.82~\mathrm{days}$) around a V=13.05 G0 star. We find a linear drift in the radial velocities of WASP-171 spanning 3.5 years, indicating the possibility of an additional outer planet or stellar companion. WASP-175b is an inflated hot Jupiter ($M=0.99 \pm 0.13~\mathrm{M_{Jup}}, R=1.208 \pm 0.081 ~\mathrm{R_{Jup}}$, $P=3.07~\mathrm{days}$) around a V=12.04 F7 star, which possibly is part of a binary system with a star 7.9\arcsec\ away. WASP-182b is a bloated sub-Saturn mass planet ($M=0.148 \pm 0.011~\mathrm{M_{Jup}}, R=0.850\pm 0.030 ~\mathrm{R_{Jup}}$) around a metal rich V=11.98 G5 star ([Fe/H]$=0.27 \pm 0.11$). With a orbital period of $P=3.377~\mathrm{days}$, it sits right in the apex of the sub-Jovian desert, bordering the upper- and lower edge of the desert in both the mass-period and radius-period plane. WASP-169b, WASP-175b and WASP-182b are promising targets for atmospheric characterisation through transmission spectroscopy, with expected transmission signals of 121, 150 and 264 ppm respectively., Comment: Published in MNRAS Aug 23, 2019

Published
2019
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244. Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared

Author

Burdanov, A. Y., Lederer, S. M., Gillon, M., Delrez, L., Ducrot, E., de Wit, J., Jehin, E., Triaud, A. H. M. J., Lidman, C., Spitler, L., Demory, B. -O., Queloz, D., Van Grootel, V., Burdanov, A. Y., Lederer, S. M., Gillon, M., Delrez, L., Ducrot, E., de Wit, J., Jehin, E., Triaud, A. H. M. J., Lidman, C., Spitler, L., Demory, B. -O., Queloz, D., and Van Grootel, V.

Abstract

The TRAPPIST-1 planetary system is a favorable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible obstacle to this technique could come from the photospheric heterogeneity of the host star that could affect planetary signatures in the transit transmission spectra. To constrain further this possibility, we gathered an extensive photometric data set of 25 TRAPPIST-1 transits observed in the near-IR J band (1.2 $\mu$m) with the UKIRT and the AAT, and in the NB2090 band (2.1 $\mu$m) with the VLT during the period 2015-2018. In our analysis of these data, we used a special strategy aiming to ensure uniformity in our measurements and robustness in our conclusions. We reach a photometric precision of $\sim0.003$ (RMS of the residuals), and we detect no significant temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the period of three years. The few transit depths measured for planets d and f hint towards some level of variability, but more measurements will be required for confirmation. Our depth measurements for planets b and c disagree with the stellar contamination spectra originating from the possible existence of bright spots of temperature 4500 K. We report updated transmission spectra for the six inner planets of the system which are globally flat for planets b and g and some structures are seen for planets c, d, e, and f., Comment: accepted for publication in MNRAS

Published
2019
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245. WASP-180Ab: Doppler tomography of an hot Jupiter orbiting the primary star in a visual binary

Author

Temple, L. Y., Hellier, C., Anderson, D. R., Barkaoui, K., Bouchy, F., Brown, D. J. A., Burdanov, A., Cameron, A. Collier, Delrez, L., Ducrot, E., Evans, D., Gillon, M., Jehin, E., Lendl, M., Maxted, P. F. L., McCormac, J., Murray, C., Nielsen, L. D., Pepe, F., Pollacco, D., Queloz, D., Ségransan, D., Smalley, B., Thompson, S., Triaud, A. H. M. J., Turner, O. D., Udry, S., West, R. G., Zouhair, B., Temple, L. Y., Hellier, C., Anderson, D. R., Barkaoui, K., Bouchy, F., Brown, D. J. A., Burdanov, A., Cameron, A. Collier, Delrez, L., Ducrot, E., Evans, D., Gillon, M., Jehin, E., Lendl, M., Maxted, P. F. L., McCormac, J., Murray, C., Nielsen, L. D., Pepe, F., Pollacco, D., Queloz, D., Ségransan, D., Smalley, B., Thompson, S., Triaud, A. H. M. J., Turner, O. D., Udry, S., West, R. G., and Zouhair, B.

Abstract

We report the discovery and characterisation of WASP-180Ab, a hot Jupiter confirmed by the detection of its Doppler shadow and by measuring its mass using radial velocities. We find the 0.9 $\pm$ 0.1 $M_{\rm Jup}$, 1.24 $\pm$ 0.04 $R_{\rm Jup}$ planet to be in a misaligned, retrograde orbit around an F7 star with $T_{\rm eff}$ = 6500K and a moderate rotation speed of vsini = 19.9 km s$^{-1}$. The host star is the primary of a $V$ = 10.7 binary, where a secondary separated by 5$''$ ($\sim$1200 AU) contributes $\sim$30% of the light. WASP-180Ab therefore adds to a small sample of transiting hot Jupiters known in binary systems. A 4.6-day modulation seen in the WASP data is likely to be the rotational modulation of the companion star, WASP-180B., Comment: 9 pages, 6 figures, accepted by MNRAS

Published
2019
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246. The discovery of WASP-134b, WASP-134c, WASP-137b, WASP-143b and WASP-146b: three hot Jupiters and a pair of warm Jupiters orbiting Solar-type stars

Author

Anderson, D. R., Bouchy, F., Brown, D. J. A., Cameron, A. Collier, Delrez, L., Gillon, M., Hern��ndez, J. I. Gonz��lez, Hellier, C., Jehin, E., Lendl, M., Maxted, P. F. L., Neveu-VanMalle, M., Nielsen, L. D., Pepe, F., Perger, M., Pollacco, D., Queloz, D., Rey, J., S��gransan, D., Smalley, B., Toledo-Padr��n, B., Triaud, A. H. M. J., Turner, O. D., Udry, S., and West, R. G.

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), FOS: Physical sciences, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery by WASP of five planets orbiting moderately bright ($V$ = 11.0-12.9) Solar-type stars. WASP-137b, WASP-143b and WASP-146b are typical hot Jupiters in orbits of 3-4 d and with masses in the range 0.68--1.11 $M_{\rm Jup}$. WASP-134 is a metal-rich ([Fe/H] = +0.40 $\pm$ 0.07]) G4 star orbited by two warm Jupiters: WASP-134b ($M_{\rm pl}$ = 1.41 $M_{\rm Jup}$; $P = 10.1$ d; $e = 0.15 \pm 0.01$; $T_{\rm eql}$ = 950 K) and WASP-134c ($M_{\rm pl} \sin i$ = 0.70 $M_{\rm Jup}$; $P = 70.0$ d; $e = 0.17 \pm 0.09$; $T_{\rm eql}$ = 500 K). From observations of the Rossiter-McLaughlin effect of WASP-134b, we find its orbit to be misaligned with the spin of its star ($\lambda = -44 \pm 10^\circ$). WASP-134 is a rare example of a system with a short-period giant planet and a nearby giant companion. In-situ formation or disc migration seem more likely explanations for such systems than does high-eccentricity migration., Comment: Submitted to AJ. 10 pages, 8 figures, 4 tables

Published
2018

247. The 0.8-4.5$��$m broadband transmission spectra of TRAPPIST-1 planets

Author

Ducrot, E., Sestovic, M., Morris, B. M., Gillon, M., Triaud, A. H. M. J., de Wit, J., Thimmarayappa, D., Agol, E., Almleaky, Y., Burdanov, A., Burgasser, A. J., Delrez, L., Demory, B-O., Jehin, E., Leconte, J., McCormac, J., Murray, C., Queloz, D., Selsis, F., Thompson, S., and Van Grootel, V.

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The TRAPPIST-1 planetary system represents an exceptional opportunity for the atmospheric characterization of temperate terrestrial exoplanets with the upcoming James Webb Space Telescope (JWST). Assessing the potential impact of stellar contamination on the planets' transit transmission spectra is an essential precursor step to this characterization. Planetary transits themselves can be used to scan the stellar photosphere and to constrain its heterogeneity through transit depth variations in time and wavelength. In this context, we present our analysis of 169 transits observed in the optical from space with K2 and from the ground with the SPECULOOS and Liverpool telescopes. Combining our measured transit depths with literature results gathered in the mid/near-IR with Spitzer/IRAC and HST/WFC3, we construct the broadband transmission spectra of the TRAPPIST-1 planets over the 0.8-4.5 $��$m spectral range. While planets b, d, and f spectra show some structures at the 200-300ppm level, the four others are globally flat. Even if we cannot discard their instrumental origins, two scenarios seem to be favored by the data: a stellar photosphere dominated by a few high-latitude giant (cold) spots, or, alternatively, by a few small and hot (3500-4000K) faculae. In both cases, the stellar contamination of the transit transmission spectra is expected to be less dramatic than predicted in recent papers. Nevertheless, based on our results, stellar contamination can still be of comparable or greater order than planetary atmospheric signals at certain wavelengths. Understanding and correcting the effects of stellar heterogeneity therefore appears essential to prepare the exploration of TRAPPIST-1's with JWST., Accepted for publication on AJ on 2018 August 31, published on 2018 October 22

Published
2018
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248. A low-density hot Jupiter in a near-aligned, 4.5-day orbit around a $V$ = 10.8, F5V star

Author

Anderson, D. R., Bouchy, F., Brown, D. J. A., Burdanov, A., Cameron, A. Collier, Delrez, L., Gillon, M., Hellier, C., Jehin, E., Lendl, M., Maxted, P. F. L., Nielsen, L. D., Pepe, F., Pollacco, D., Queloz, D., Ségransan, D., Smalley, B., Temple, L. Y., Triaud, A. H. M. J., Udry, S., and West, R. G.

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), FOS: Physical sciences, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the independent discovery and characterisation of a hot Jupiter in a 4.5-d, transiting orbit around the star TYC 7282-1298-1 ($V$ = 10.8, F5V). The planet has been pursued by the NGTS team as NGTS-2b and by ourselves as WASP-179b. We characterised the system using a combination of photometry from WASP-South and TRAPPIST-South, and spectra from CORALIE (around the orbit) and HARPS (through the transit). We find the planet's orbit to be nearly aligned with its star's spin. From a detection of the Rossiter-McLaughlin effect, we measure a projected stellar obliquity of $\lambda = -19 \pm 6^\circ$. From line-profile tomography of the same spectra, we measure $\lambda = -11 \pm 5^\circ$. We find the planet to have a low density ($M_{\rm P}$ = 0.67 $\pm$ 0.09 $M_{\rm Jup}$, $R_{\rm P}$ = 1.54 $\pm$ 0.06 $R_{\rm Jup}$), which, along with its moderately bright host star, makes it a good target for transmission spectroscopy. We find a lower stellar mass ($M_*$ = $1.30 \pm 0.07$ $M_\odot$) than reported by the NGTS team ($M_*$ = $1.64 \pm 0.21$ $M_\odot$), though the difference is only $1.5$ $\sigma$., Comment: Submitted to AJ. 9 pages, 6 figures, 5 tables

Published
2018
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249. High-precision multiwavelength eclipse photometry of the ultra-hot gas giant exoplanetWASP-103 b

Author

Delrez, L, Madhusudhan, N, Lendl, M, Gillon, M, Anderson, DR, Neveu-VanMalle, M, Bouchy, F, Burdanov, A, Collier-Cameron, A, Demory, BO, Hellier, C, Jehin, E, Magain, P, Maxted, PFL, Queloz, D, Smalley, B, Triaud, AHMJ, Delrez, Laetitia [0000-0001-6108-4808], Nikku, Madhusudhan [0000-0002-4869-000X], Queloz, Didier [0000-0002-3012-0316], Triaud, Amaury [0000-0002-5510-8751], and Apollo - University of Cambridge Repository

Subjects
planets and satellites: atmospheres, stars: individual: WASP-103, techniques: photometric, techniques: radial velocities, Astrophysics::Earth and Planetary Astrophysics, planetary systems
Abstract

© 2017 The Author(s). We present 16 occultation and three transit light curves for the ultra-short period hot Jupiter WASP-103b, in addition to five new radial velocity measurements. We combine these observations with archival data and perform a global analysis of the resulting extensive data set, accounting for the contamination from a nearby star. We detect the thermal emission of the planet in both the z' and KS bands, the measured occultation depths being 699±110 ppm (6.4σ) and 3567 -350 +400 ppm (10.2σ), respectively. We use these two measurements, together with recently published HST/WFC3 data, to derive joint constraints on the properties of WASP- 103b's dayside atmosphere. On one hand, we find that the z' band and WFC3 data are best fit by an isothermal atmosphere at 2900K or an atmosphere with a low H 2 O abundance. On the other hand, we find an unexpected excess in the K S band measured flux compared to these models, which requires confirmation with additional observations before any interpretation can be given. From our global data analysis, we also derive a broad-band optical transmission spectrum that shows a minimum around 700 nm and increasing values towards both shorter and longer wavelengths. This is in agreement with a previous study based on a large fraction of the archival transit light curves used in our analysis. The unusual profile of this transmission spectrum is poorly matched by theoretical spectra and is not confirmed by more recent observations at higher spectral resolution. Additional data, in both emission and transmission, are required to better constrain the atmospheric properties of WASP-103b.

Published
2018

250. WASP-South hot Jupiters: WASP-178b, WASP-184b, WASP-185b, and WASP-192b

Author

Hellier, Coel, primary, Anderson, D R, additional, Barkaoui, K, additional, Benkhaldoun, Z, additional, Bouchy, F, additional, Burdanov, A, additional, Cameron, A Collier, additional, Delrez, L, additional, Gillon, M, additional, Jehin, E, additional, Nielsen, L D, additional, Maxted, P F L, additional, Pepe, F, additional, Pollacco, D, additional, Pozuelos, F J, additional, Queloz, D, additional, Ségransan, D, additional, Smalley, B, additional, Triaud, A H M J, additional, Turner, O D, additional, Udry, S, additional, and West, R G, additional

Published
2019
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