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1. EPOXI: COMET 103P/HARTLEY 2 OBSERVATIONS FROM A WORLDWIDE CAMPAIGN

Author

Meech, KJ, A’Hearn, MF, Adams, JA, Bacci, P, Bai, J, Barrera, L, Battelino, M, Bauer, JM, Becklin, E, Bhatt, B, Biver, N, Bockelée-Morvan, D, Bodewits, D, Böhnhardt, H, Boissier, J, Bonev, BP, Borghini, W, Brucato, JR, Bryssinck, E, Buie, MW, Canovas, H, Castellano, D, Charnley, SB, Chen, WP, Chiang, P, Choi, Y-J, Christian, DJ, Chuang, Y-L, Cochran, AL, Colom, P, Combi, MR, Coulson, IM, Crovisier, J, Dello Russo, N, Dennerl, K, DeWahl, K, DiSanti, MA, Facchini, M, Farnham, TL, Fernández, Y, Florén, HG, Frisk, U, Fujiyoshi, T, Furusho, R, Fuse, T, Galli, G, García-Hernández, DA, Gersch, A, Getu, Z, Gibb, EL, Gillon, M, Guido, E, Guillermo, RA, Hadamcik, E, Hainaut, O, Hammel, HB, Harker, DE, Harmon, JK, Harris, WM, Hartogh, P, Hashimoto, M, Häusler, B, Herter, T, Hjalmarson, A, Holland, ST, Honda, M, Hosseini, S, Howell, ES, Howes, N, Hsieh, HH, Hsiao, H-Y, Hutsemékers, D, Immler, SM, Jackson, WM, Jeffers, SV, Jehin, E, Jones, TJ, de Juan Ovelar, M, Kaluna, HM, Karlsson, T, Kawakita, H, Keane, JV, Keller, LD, Kelley, MS, Kinoshita, D, Kiselev, NN, Kleyna, J, Knight, MM, Kobayashi, H, Kobulnicky, HA, Kolokolova, L, Kreiny, M, Kuan, Y-J, Küppers, M, Lacruz, JM, Landsman, WB, Lara, LM, Lecacheux, A, Levasseur-Regourd, AC, and Li, B

Subjects
comets: individual, Astronomical and Space Sciences, Astronomy & Astrophysics
Abstract

Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is small and dark, and exhibited a very rapidly changing rotation period. Prior to the onset of activity, the period was 16.4hr. Starting in 2010 August the period changed from 16.6hr to near 19hr in December. With respect to dust composition, most volatiles and carbon and nitrogen isotope ratios, the comet is similar to other Jupiter-family comets. What is unusual is the dominance of CO 2 -driven activity near perihelion, which likely persists out to aphelion. Near perihelion the comet nucleus was surrounded by a large halo of water-ice grains that contributed significantly to the total water production. © 2011. The American Astronomical Society. All rights reserved..

Published
2011

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

Author

Swayne, MI, Maxted, PFL, Triaud, AHMJ, Sousa, SG, Broeg, C, Florén, HG, Guterman, P, Simon, AE, Boisse, I, Bonfanti, A, Martin, D, Santerne, A, Salmon, S, Standing, MR, Van Grootel, V, Wilson, TG, Alibert, Y, Alonso, R, Anglada Escudé, G, Asquier, J, Bárczy, T, Barrado, D, Barros, SCC, Battley, M, Baumjohann, W, Beck, M, Beck, T, Bekkelien, A, Benz, W, Billot, N, Bonfils, X, Brandeker, A, Busch, MD, Cabrera, J, Charnoz, S, Collier Cameron, A, Csizmadia, S, Davies, MB, Deleuil, M, Deline, A, Delrez, L, Demangeon, ODS, Demory, BO, 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, KG, 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, G, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Ribas, I, Santos, NC, Scandariato, G, Ségransan, D, Smith, AMS, Steinberger, M, Steller, M, Szabó, GM, Thomas, N, Udry, S, Walter, I, Walton, NA, Willett, E, Swayne, MI [0000-0002-2609-3159], Triaud, AHMJ [0000-0002-5510-8751], Sousa, SG [0000-0001-9047-2965], Santerne, A [0000-0002-3586-1316], Wilson, TG [0000-0001-8749-1962], Battley, M [0000-0002-1357-9774], Baumjohann, W [0000-0001-6271-0110], Collier Cameron, A [0000-0002-8863-7828], Csizmadia, S [0000-0001-6803-9698], Delrez, L [0000-0001-6108-4808], Fridlund, M [0000-0002-0855-8426], Gandolfi, D [0000-0001-8627-9628], Hoyer, S [0000-0003-3477-2466], Lendl, M [0000-0001-9699-1459], Miller, N [0000-0001-9550-1198], and Apollo - University of Cambridge Repository

Subjects
techniques: photometric, stars: low-mass, Astrophysics::Solar and Stellar Astrophysics, binaries: eclipsing, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, stars: fundamental parameters, Astrophysics::Galaxy Astrophysics, techniques: spectroscopic
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

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

Author

Swayne, MI, Maxted, PFL, Triaud, AHMJ, Sousa, SG, Broeg, C, Florén, HG, Guterman, P, Simon, AE, Boisse, I, Bonfanti, A, Martin, D, Santerne, A, Salmon, S, Standing, MR, Van Grootel, V, Wilson, TG, Alibert, Y, Alonso, R, Anglada Escudé, G, Asquier, J, Bárczy, T, Barrado, D, Barros, SCC, Battley, M, Baumjohann, W, Beck, M, Beck, T, Bekkelien, A, Benz, W, Billot, N, Bonfils, X, Brandeker, A, Busch, MD, Cabrera, J, Charnoz, S, Collier Cameron, A, Csizmadia, S, Davies, MB, Deleuil, M, Deline, A, Delrez, L, Demangeon, ODS, Demory, BO, 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, KG, 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, G, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Ribas, I, Santos, NC, Scandariato, G, Ségransan, D, Smith, AMS, Steinberger, M, Steller, M, Szabó, GM, Thomas, N, Udry, S, Walter, I, Walton, NA, and Willett, E

Subjects
techniques: photometric, 13. Climate action, stars: low-mass, Astrophysics::Solar and Stellar Astrophysics, binaries: eclipsing, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, stars: fundamental parameters, Astrophysics::Galaxy Astrophysics, techniques: spectroscopic, 3. Good health
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.

4. Author Correction: A dense ring of the trans-Neptunian object Quaoar outside its Roche limit.

Author

Morgado BE, Sicardy B, Braga-Ribas F, Ortiz JL, Salo H, Vachier F, Desmars J, Pereira CL, Santos-Sanz P, Sfair R, de Santana T, Assafin M, Vieira-Martins R, Gomes-Júnior AR, Margoti G, Dhillon VS, Fernández-Valenzuela E, Broughton J, Bradshaw J, Langersek R, Benedetti-Rossi G, Souami D, Holler BJ, Kretlow M, Boufleur RC, Camargo JIB, Duffard R, Beisker W, Morales N, Lecacheux J, Rommel FL, Herald D, Benz W, Jehin E, Jankowsky F, Marsh TR, Littlefair SP, Bruno G, Pagano I, Brandeker A, Collier-Cameron A, Florén HG, Hara N, Olofsson G, Wilson TG, Benkhaldoun Z, Busuttil R, Burdanov A, Ferrais M, Gault D, Gillon M, Hanna W, Kerr S, Kolb U, Nosworthy P, Sebastian D, Snodgrass C, Teng JP, and de Wit J

Published
2024
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5. A dense ring of the trans-Neptunian object Quaoar outside its Roche limit.

Author

Morgado BE, Sicardy B, Braga-Ribas F, Ortiz JL, Salo H, Vachier F, Desmars J, Pereira CL, Santos-Sanz P, Sfair R, de Santana T, Assafin M, Vieira-Martins R, Gomes-Júnior AR, Margoti G, Dhillon VS, Fernández-Valenzuela E, Broughton J, Bradshaw J, Langersek R, Benedetti-Rossi G, Souami D, Holler BJ, Kretlow M, Boufleur RC, Camargo JIB, Duffard R, Beisker W, Morales N, Lecacheux J, Rommel FL, Herald D, Benz W, Jehin E, Jankowsky F, Marsh TR, Littlefair SP, Bruno G, Pagano I, Brandeker A, Collier-Cameron A, Florén HG, Hara N, Olofsson G, Wilson TG, Benkhaldoun Z, Busuttil R, Burdanov A, Ferrais M, Gault D, Gillon M, Hanna W, Kerr S, Kolb U, Nosworthy P, Sebastian D, Snodgrass C, Teng JP, and de Wit J

Abstract

Planetary rings are observed not only around giant planets 1 , but also around small bodies such as the Centaur Chariklo 2 and the dwarf planet Haumea 3 . Up to now, all known dense rings were located close enough to their parent bodies, being inside the Roche limit, where tidal forces prevent material with reasonable densities from aggregating into a satellite. Here we report observations of an inhomogeneous ring around the trans-Neptunian body (50000) Quaoar. This trans-Neptunian object has an estimated radius 4 of 555 km and possesses a roughly 80-km satellite 5 (Weywot) that orbits at 24 Quaoar radii 6,7 . The detected ring orbits at 7.4 radii from the central body, which is well outside Quaoar's classical Roche limit, thus indicating that this limit does not always determine where ring material can survive. Our local collisional simulations show that elastic collisions, based on laboratory experiments 8 , can maintain a ring far away from the body. Moreover, Quaoar's ring orbits close to the 1/3 spin-orbit resonance 9 with Quaoar, a property shared by Chariklo's 2,10,11 and Haumea's 3 rings, suggesting that this resonance plays a key role in ring confinement for small bodies., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Published
2023
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7. Shedding new light on the Crab with polarized X-rays.

Author

Chauvin M, Florén HG, Friis M, Jackson M, Kamae T, Kataoka J, Kawano T, Kiss M, Mikhalev V, Mizuno T, Ohashi N, Stana T, Tajima H, Takahashi H, Uchida N, and Pearce M

Abstract

Strong magnetic fields, synchrotron emission, and Compton scattering are omnipresent in compact celestial X-ray sources. Emissions in the X-ray energy band are consequently expected to be linearly polarized. X-ray polarimetry provides a unique diagnostic to study the location and fundamental mechanisms behind emission processes. The polarization of emissions from a bright celestial X-ray source, the Crab, is reported here for the first time in the hard X-ray band (~20-160 keV). The Crab is a complex system consisting of a central pulsar, a diffuse pulsar wind nebula, as well as structures in the inner nebula including a jet and torus. Measurements are made by a purpose-built and calibrated polarimeter, PoGO+. The polarization vector is found to be aligned with the spin axis of the pulsar for a polarization fraction, PF = (20.9 ± 5.0)%. This is higher than that of the optical diffuse nebula, implying a more compact emission site, though not as compact as, e.g., the synchrotron knot. Contrary to measurements at higher energies, no significant temporal evolution of phase-integrated polarisation parameters is observed. The polarization parameters for the pulsar itself are measured for the first time in the X-ray energy band and are consistent with observations at optical wavelengths.

Published
2017
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