occultations; planets and satellites: individual: Phoebe
Abstract :
[en] We report six stellar occultations by Phoebe (Saturn IX), an irregular satellite of Saturn, obtained between mid-2017 and mid-2019. The 2017 July 6 event was the first stellar occultation by an irregular satellite ever observed. The occultation chords were compared to a 3D shape model of the satellite obtained from Cassini observations. The rotation period available in the literature led to a sub-observer point at the moment of the observed occultations where the chords could not fit the 3D model. A procedure was developed to identify the correct sub-observer longitude. It allowed us to obtain the rotation period with improved precision compared to the currently known value from literature. We show that the difference between the observed and the predicted sub-observer longitude suggests two possible solutions for the rotation period. By comparing these values with recently observed rotational light curves and single- chord stellar occultations, we can identify the best solution for Phoebe's rotational period as 9.27365 ± 0.00002 h. From the stellar occultations, we also obtained six geocentric astrometric positions in the ICRS as realized by the Gaia DR2 with uncertainties at the 1-mas level.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Gomes-Júnior, A. Ramos; UNESP - São Paulo State University, Grupo de Dinâmica Orbital e Planetologia, Guaratinguetá - SP 12516-410, Brazil ; Observatório do Valongo/UFRJ, Ladeira Pedro Antônio 43, Rio de Janeiro - RJ 20080-090, Brazil ; Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil
Assafin, Marcelo; Observatório do Valongo/UFRJ, Ladeira Pedro Antônio 43, Rio de Janeiro - RJ 20080-090, Brazil ; Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil
Braga-Ribas, Felipe; Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil ; Federal University of Technology - Paraná (UTFPR / DAFIS), Rua Sete de Setembro, 3165, Curitiba, PR 80230-901, Brazil ; Observatório Nacional/MCTI, R. General José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil ; LESIA, Observatoire de Paris - Section Meudon, 5 Place Jules Janssen - 92195 Meudon Cedex, France
Benedetti-Rossi, Gustavo; Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil ; Observatório Nacional/MCTI, R. General José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil ; LESIA, Observatoire de Paris - Section Meudon, 5 Place Jules Janssen - 92195 Meudon Cedex, France
Morgado, Bruno Eduardo; Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil ; Observatório Nacional/MCTI, R. General José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil
Camargo, J. I. B.; Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil ; Observatório Nacional/MCTI, R. General José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil
Vieira-Martins, R.; Observatório do Valongo/UFRJ, Ladeira Pedro Antônio 43, Rio de Janeiro - RJ 20080-090, Brazil ; Laboratório Interinstitucional de e-Astronomia - LIneA, Rua Gal. José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil ; Observatório Nacional/MCTI, R. General José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil
Desmars, Josselin; Institut Poytechnique des Sciences Avancées IPSA, 63 boulevard de Brandebourg, Ivry-sur-Seine F-94200, France ; Institut de Mécanique Céleste et de Calcul des Éphémérides, IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ Paris 06, Univ. Lille, 77 Av. Denfert-Rochereau, Paris F-75014, France
Sicardy, B.; LESIA, Observatoire de Paris - Section Meudon, 5 Place Jules Janssen - 92195 Meudon Cedex, France
Barry, T.; Penrith Observatory, Western Sydney University, School of Computing, Engineering and Mathematics, Kingswood, NSW 2747, Australia
Campbell-White, J.; SUPA, School of Science and Engineering, University of Dundee, Nethergate, Dundee DD1 4HN, UK
Fernández-Lajús, E.; Facultad de Ciencias Astronómicas y Geofísicas - Universidad Nacional de La Plata, Paseo del Bosque S/N - 1900, La Plata, Argentina ; Instituto de Astrofísica de La Plata (CCT La Plata - CONICET/UNLP), Paseo del Bosque S/N - 1900, La Plata, Argentina
Giles, D.; Penrith Observatory, Western Sydney University, School of Computing, Engineering and Mathematics, Kingswood, NSW 2747, Australia
Hanna, W.; Royal Astronomical Society of New Zealand, Occultation Section ; International Occultation Timing Association (IOTA), Columbia Falls, MT 59912, USA
Hayamizu, T.; Japan Occultation Information Network (JOIN), Japan
Hirose, T.; Japan Occultation Information Network (JOIN), Japan
De Horta, A.; Penrith Observatory, Western Sydney University, School of Computing, Engineering and Mathematics, Kingswood, NSW 2747, Australia
Horvat, R.; Penrith Observatory, Western Sydney University, School of Computing, Engineering and Mathematics, Kingswood, NSW 2747, Australia
Hosoi, K.; Japan Occultation Information Network (JOIN), Japan
Jehin, Emmanuel ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Kerr, S.; Astronomical Association of Queensland, 5 Curtis Street, Pimpama QLD 4209, Australia ; Occultation Section of the Royal Astronomical Society of New Zealand (RASNZ), Wellington PO Box 3181, New Zealand
Machado, D. I.; Polo Astronômico Casimiro Montenegro Filho/FPTI-BR, Avenida Tancredo Neves 6731, Foz do Iguaçu, PR 85867-900, Brazil ; Universidade Estadual do Oeste do Paraná, Avenida Tarquínio Joslin dos Santos 1300, Foz do Iguaçu, PR 85870-650, Brazil
Mammana, L. A.; Facultad de Ciencias Astronómicas y Geofísicas - Universidad Nacional de La Plata, Paseo del Bosque S/N - 1900, La Plata, Argentina ; Complejo Astronómico El Leoncito (CASLEO), Av. España 1512 Sur, J5402DSP - San Juan - Argentina
Maybour, D.; Penrith Observatory, Western Sydney University, School of Computing, Engineering and Mathematics, Kingswood, NSW 2747, Australia
Owada, M.; Japan Occultation Information Network (JOIN), Japan
Rahvar, S.; Department of Physics, Sharif University of Technology, P.O. Box 11155-9161 Tehran, Iran
Snodgrass, C.; Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK)
Archinal B. A. et al., 2018, Celest. Mech. Dyn. Astron., 130, 22
Assafin M., Vieira-Martins R., Camargo J. I. B., Andrei A. H., da Silva Neto D. N., Braga-Ribas F., 2011, in Tanga P., Thuillot W., eds, Gaia followup network for the Solar system objects: Gaia FUN-SSO Workshop Proc. IMCCE, Paris, p. 85
Bauer J.M., Buratti B. J., Simonelli D. P., Owen W.M., Jr., 2004, ApJ, 610, L57
Benedetti-Rossi G. et al., 2016, AJ, 152, 156
Braga-Ribas F. et al., 2014, Nature, 508, 72
Gaia Collaboration, 2018, A&A, 616, A1
Clark R. N. et al., 2005, Nature, 435, 66
Colvin T., Davies M. E., Rogers P. G., Heller J., 1989, Technical Report STI/Recon. Tech. Rep. N-2934-NASA, Phoebe: A Preliminary Control Network and Rotational Elements. NASA, Santa Monica, CA
Desmars J., Li S. N., Tajeddine R., Peng Q. Y., Tang Z. H., 2013, A&A, 553, A36
Gaskell R. W., 2013, NASA Planet. Data Syst., 207
Gladman B. et al., 2001, Nature, 412, 163
Gomes-Júnior A. R., Assafin M., Beauvalet L., Desmars J., Vieira-Martins R., Camargo J. I. B., Morgado B. E., Braga-Ribas F., 2016, MNRAS, 462, 1351
Jehin E. et al., 2011, The Messenger, 145, 2
Johnson T. V., Lunine J. I., 2005, Nature, 435, 69
Michalik D., Lindegren L., Hobbs D., 2015, A&A, 574, A115
Pickering E. C., 1899, ApJ, 9, 274
Porco C. C. et al., 2005, Science, 307, 1237
Ross F. E., 1905, Ann. Harv. Coll. Obs., 53, 101
Sicardy B. et al., 2011, Nature, 478, 493
Skottfelt J. et al., 2015, A&A, 574, A54
Thomas P., 2010, Icarus, 208, 395
van Belle G. T., 1999, PASP, 111, 1515
Zacharias N., Finch C. T., Girard T. M., Henden A., Bartlett J. L., Monet D. G., Zacharias M. I., 2013, AJ, 145, 44
