The first observed stellar occultations by the irregular satellite Phoebe (Saturn IX) and improved rotational period-Reference-Cited by-同舟云学术

The first observed stellar occultations by the irregular satellite Phoebe (Saturn IX) and improved rotational period

Published:2019-12-19 Issue:1 Volume:492 Page:770-781
ISSN:0035-8711
Container-title:Monthly Notices of the Royal Astronomical Society
language:en
Short-container-title:

Author:

Gomes-Júnior A R¹²³^ORCID,Assafin M²³,Braga-Ribas F³⁴⁵⁶,Benedetti-Rossi G³⁵⁶^ORCID,Morgado B E³⁵^ORCID,Camargo J I B³⁵,Vieira-Martins R²³⁵,Desmars J⁷⁸,Sicardy B⁶,Barry T⁹,Campbell-White J¹⁰^ORCID,Fernández-Lajús E¹¹¹²,Giles D⁹,Hanna W¹³,Hayamizu T¹⁴,Hirose T¹⁴,De Horta A⁹,Horvat R⁹,Hosoi K¹⁴,Jehin E¹⁵,Kerr S¹⁶¹⁷,Machado D I¹⁸¹⁹,Mammana L A¹¹²⁰,Maybour D⁹,Owada M¹⁴,Rahvar S²¹^ORCID,Snodgrass C²²

Affiliation:

1. UNESP – São Paulo State University, Grupo de Dinâmica Orbital e Planetologia, Guaratinguetá - SP 12516-410, Brazil

2. Observatório do Valongo/UFRJ, Ladeira Pedro Antônio 43, Rio de Janeiro - RJ 20080-090, Brazil

3. Laboratório Interinstitucional de e-Astronomia – LIneA, Rua Gal. José Cristino 77, Rio de Janeiro - RJ 20921-400, Brazil

4. Federal University of Technology – Paraná (UTFPR / DAFIS), Rua Sete de Setembro, 3165, Curitiba, PR 80230-901, Brazil

5. Observatório Nacional/MCTI, R. General José Cristino 77, Rio de Janeiro – RJ 20921-400, Brazil

6. LESIA, Observatoire de Paris – Section Meudon, 5 Place Jules Janssen – 92195 Meudon Cedex, France

7. Institut Poytechnique des Sciences Avancées IPSA, 63 boulevard de Brandebourg, Ivry-sur-Seine F-94200, France

8. 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

9. Penrith Observatory, Western Sydney University, School of Computing, Engineering and Mathematics, Kingswood, NSW 2747, Australia

10. SUPA, School of Science and Engineering, University of Dundee, Nethergate, Dundee DD1 4HN, UK

11. Facultad de Ciencias Astronómicas y Geofísicas – Universidad Nacional de La Plata, Paseo del Bosque S/N – 1900, La Plata, Argentina

12. Instituto de Astrofísica de La Plata (CCT La Plata – CONICET/UNLP), Paseo del Bosque S/N – 1900, La Plata, Argentina

13. Royal Astronomical Society of New Zealand, Occultation Section; International Occultation Timing Association (IOTA), Columbia Falls, MT 59912, USA

14. Japan Occultation Information Network (JOIN), Japan

15. Space sciences, Technologies & Astrophysics Research (STAR) Institute, Université de Liège, Liège B-4000, Belgium

16. Astronomical Association of Queensland, 5 Curtis Street, Pimpama QLD 4209, Australia

17. Occultation Section of the Royal Astronomical Society of New Zealand (RASNZ), Wellington PO Box 3181, New Zealand

18. Polo Astronômico Casimiro Montenegro Filho/FPTI-BR, Avenida Tancredo Neves 6731, Foz do Iguaçu, PR 85867-900, Brazil

19. Universidade Estadual do Oeste do Paraná, Avenida Tarquínio Joslin dos Santos 1300, Foz do Iguaçu, PR 85870-650, Brazil

20. Complejo Astronómico El Leoncito (CASLEO), Av. España 1512 Sur, J5402DSP - San Juan – Argentina

21. Department of Physics, Sharif University of Technology, P.O. Box 11155–9161 Tehran, Iran

22. Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK

Abstract

ABSTRACT 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.

Funder

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo à Pesquisa do Estado de São Paulo

Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro

Ministério da Ciência, Tecnologia, Inovações e Comunicações

U.S. National Optical Astronomy Observatory

University of North Carolina, Chapel Hill

Michigan State University

Complejo Astronómico El Leoncito

Consejo Nacional de Investigaciones Cientf́icas y Técnicas de la República Argentina

National Universities of La Plata