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Your search keyword '"Smith, Alexis M. S."' showing total 8 results
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8 results on '"Smith, Alexis M. S."'

1. A sub-Neptune transiting the young field star HD 18599 at 40 pc

Author

de Leon, Jerome P., Livingston, John H., Jenkins, James S., Vines, Jose I., Wittenmyer, Robert A., Clark, Jake T., Winn, Joshua I. M., Addison, Brett, Ballard, Sarah, Bayliss, Daniel, Beichman, Charles, Benneke, Björn, Berardo, David Anthony, Bowler, Brendan P., Brown, Tim, Bryant, Edward M., Christiansen, Jessie, Ciardi, David, Collins, Karen A., Collins, Kevin I., Crossfield, Ian, Deming, Drake, Dragomir, Diana, Dressing, Courtney D., Fukui, Akihiko, Gan, Tianjun, Giacalone, Steven, Gill, Samuel, Alvarez, Erica Gonz\' alez, Hesse, Katharine, Horner, Jonathan, Howell, Steve B., Jenkins, Jon M., Kane, Stephen R., Kendall, Alicia, Kielkopf, John F., Kreidberg, Laura, Latham, David W., Liu, Huigen, Lund, Michael B., Matson, Rachel, Matthews, Elisabeth, Mengel, Matthew W., Morales, Farisa, Mori, Mayuko, Narita, Norio, Nishiumi, Taku, Okumura, Jack, Plavchan, Peter, Quinn, Sam, Rabus, Markus, Ricker, George, Rudat, Alexander, Schlieder, Joshua, Schwarz, Richard P., Seager, Sara, Shporer, Avi, Smith, Alexis M. S., Sphorer, Avi, Stassun, Keivan, Tamura, Motohide, Tan, Thiam Guan, Tinney, C. G., Vanderspek, Roland, Gorjian, Varoujan, Werner, Michael W., West, Richard G., Wright, Duncan, Zhang, Hui, and Zhou, George

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), planets and satellites: detection, Space and Planetary Science, techniques: radial velocities, stars: individual: TOI-179, FOS: Physical sciences, Astronomy and Astrophysics, techniques: spectroscopic, Astrophysics - Earth and Planetary Astrophysics
Abstract

Transiting exoplanets orbiting young nearby stars are ideal laboratories for testing theories of planet formation and evolution. However, to date only a handful of stars with age, submitted to MNRAS

Published
2023
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2. Company for the ultra-high density, ultra-short period sub-Earth GJ 367 b: discovery of two additional low-mass planets at 11.5 and 34 days

Author

Goffo, Elisa, Gandolfi, Davide, Egger, Jo Ann, Mustill, Alexander J., Albrecht, Simon H., Hirano, Teruyuki, Kochukhov, Oleg, Astudillo-Defru, Nicola, Barragan, Oscar, Serrano, Luisa M., Hatzes, Artie P., Alibert, Yann, Guenther, Eike, Dai, Fei, Lam, Kristine W. F., Csizmadia, Szilárd, Smith, Alexis M. S., Fossati, Luca, Luque, Rafael, Rodler, Florian, Winther, Mark L., Rørsted, Jakob L., Alarcon, Javier, Bonfils, Xavier, Cochran, William D., Deeg, Hans J., Jenkins, Jon M., Korth, Judith, Livingston, John H., Meech, Annabella, Murgas, Felipe, Orell-Miquel, Jaume, Osborne, Hannah L. M., Palle, Enric, Persson, Carina M., Redfield, Seth, Ricker, George R., Seager, Sara, Vanderspek, Roland, Van Eylen, Vincent, and Winn, Joshua N.

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

GJ 367 is a bright (V $\approx$ 10.2) M1 V star that has been recently found to host a transiting ultra-short period sub-Earth on a 7.7 hr orbit. With the aim of improving the planetary mass and radius and unveiling the inner architecture of the system, we performed an intensive radial velocity follow-up campaign with the HARPS spectrograph -- collecting 371 high-precision measurements over a baseline of nearly 3 years -- and combined our Doppler measurements with new TESS observations from sectors 35 and 36. We found that GJ 367 b has a mass of $M_\mathrm{b}$ = 0.633 $\pm$ 0.050 M$_{\oplus}$ and a radius of $R_\mathrm{b}$ = 0.699 $\pm$ 0.024 R$_{\oplus}$, corresponding to precisions of 8% and 3.4%, respectively. This implies a planetary bulk density of $\rho_\mathrm{b}$ = 10.2 $\pm$ 1.3 g cm$^{-3}$, i.e., 85% higher than Earth's density. We revealed the presence of two additional non transiting low-mass companions with orbital periods of $\sim$11.5 and 34 days and minimum masses of $M_\mathrm{c}\sin{i_\mathrm{c}}$ = 4.13 $\pm$ 0.36 M$_{\oplus}$ and $M_\mathrm{d}\sin{i_\mathrm{d}}$ = 6.03 $\pm$ 0.49 M$_{\oplus}$, respectively, which lie close to the 3:1 mean motion commensurability. GJ 367 b joins the small class of high-density planets, namely the class of super-Mercuries, being the densest ultra-short period small planet known to date. Thanks to our precise mass and radius estimates, we explored the potential internal composition and structure of GJ 367 b, and found that it is expected to have an iron core with a mass fraction of 0.91$^{+0.07}_{-0.23}$. How this iron core is formed and how such a high density is reached is still not clear, and we discuss the possible pathways of formation of such a small ultra-dense planet., Comment: 28 pages, 11 figures. Accepted for publication in ApJL

Published
2023
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3. 55 Cancri e’s occultation captured with CHEOPS

Author

Demory, B.-O., Sulis, S., Meier Valdes, E., Delrez, L., Brandeker, A., Billot, N., Fortier, A., Hoyer, S., Sousa, S. G., Heng, K., Lendl, M., Krenn, A., Morris, B. M., Patel, J. A., Alibert, Y., Alonso, R., Anglada Escudé, G., Bàrczy, T., Barrado, D., Barros, S. C. C., Baumjohann, W., Beck, M., Beck, T., Benz, W., Bonfils, X., Broeg, C., Buder, M., Cabrera, J., Charnoz, S., Collier Cameron, A., Cottard, H., Csizmadia, Sz., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Ehrenreich, D., Erikson, A., Fossati, L., Fridlund, M., Gandolfi, D., Gillon, M., Güdel, M., Isaak, K. G., Kiss, L. L., Laskar, J., Lecavelier des Etangs, A., Lovis, C., Luntzer, A., Magrin, D., Marafatto, L., Maxted, P. F. L., Nascimbeni, V., Olofsson, G., Ottensamer, R., Pagano, I., Palle, E., Peter, G., Piotto, G., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Ratti, F., Rauer, H., Ribas, I., Santos, N. C., Scandariato, G., Segransan, D., Simon, A. E., Smith, Alexis M S, Steller, M., Szabó, Gy. M., Thomas, N., Udry, S., Van Grootel, V., Walton, N. A., 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), 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), Science & Technology Facilities Council, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. St Andrews Centre for Exoplanet Science

Subjects
MCC, Earth and Planetary Astrophysics (astro-ph.EP), 530 Physics, 520 Astronomy, individual: 55 Cnc e [Planets and satellites], photometric [Techniques], 500 Naturwissenschaften und Mathematik::520 Astronomie::520 Astronomie und zugeordnete Wissenschaften, FOS: Physical sciences, Astronomy and Astrophysics, 3rd-DAS, individual: 55 Cnc e, techniques: photometric, methods: observational [planets and satellites], QC Physics, [SDU]Sciences of the Universe [physics], Space and Planetary Science, QB Astronomy, observational [Methods], methods: observational, QC, planets and satellites: individual: 55 Cnc e, QB, Astrophysics - Earth and Planetary Astrophysics
Abstract

Past occultation and phase-curve observations of the ultra-short period super-Earth 55 Cnc e obtained at visible and infrared wavelengths have been challenging to reconcile with a planetary reflection and emission model. In this study, we analyse a set of 41 occultations obtained over a two-year timespan with the CHEOPS satellite. We report the detection of 55 Cnc e's occultation with an average depth of 12 ± 3 ppm. We derive a corresponding 2Ïà  upper limit on the geometric albedo of Ag < 0.55 once decontaminated from the thermal emission measured by Spitzer at 4.5 μm. CHEOPSâà €à ™ s photometric performance enables, for the first time, the detection of individual occultations of this super-Earth in the visible and identifies short-timescale photometric corrugations likely induced by stellar granulation. We also find a clear 47.3-day sinusoidal pattern in the time-dependent occultation depths that we are unable to relate to stellar noise, nor instrumental systematics, but whose planetary origin could be tested with upcoming JWST occultation observations of this iconic super-Earth., Astronomy & Astrophysics, 669, ISSN:0004-6361, ISSN:1432-0746

Published
2023
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8. Three Small Super-Earths Transiting the nearby star GJ 9827

Author

Niraula, Prajwal, Redfield, Seth, Dai, Fei, Barragan, Oscar, Gandolfi, Davide, Cauley, P. Wilson, Hirano, Teruyuki, Korth, Judith, Smith, Alexis M. S., Prieto-Arranz, Jorge, Grziwa, Sascha, Fridlund, Malcolm, Persson, Carina M., Justesen, Anders Bo, Winn, Joshua N., Albrecht, Simon, Cochran, William D., Csizmadia, Szilard, Girish Duvvuri, Endl, Michael, Hatzes, Artie P., Livingston, John H., Narita, Norio, Nespral, David, Nowak, Grzegorz, Patzold, Martin, Palle, Enric, and Eylen, Vincent

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

We report on the discovery of three transiting planets around GJ~9827. The planets have radii of 1.75$_{-0.12}^{+0.11 }$, 1.36$_{- 0.09 }^{+ 0.09}$, and 2.10$_{- 0.15 }^{+ 0.15 }$~R$_{\oplus}$, and periods of 1.20896, 3.6480, and 6.2014 days, respectively. The detection was made in Campaign 12 observations as part of our K2 survey of nearby stars. GJ~9827 is a $V = 10.39$~mag K6V star at distance of 30.3 parsecs and the nearest star to be found hosting planets by Kepler and K2. The radial velocity follow-up, high resolution imaging, and detection of multiple transiting objects near commensurability drastically reduce the false positive probability. The orbital periods of GJ~9827~b, c and d planets are very close to the 1:3:5 mean motion resonance. Our preliminary analysis shows that GJ~9827 planets are excellent candidates for atmospheric observations. Besides, the planetary radii span both sides of the rocky and gaseous divide, hence the system will be an asset in expanding our understanding of the threshold., Comment: 9 pages, 4 figures. Submitted to AAS Journals

Published
2017
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