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

We report six stellar occultations by (Saturn IX) Phoebe, an irregular satellite of Saturn, obtained between mid-2017 and mid-2019. The 2017 July 06 event is the first stellar occultation by an irregular satellite ever observed. The occultation chords were compared to a 3D shape model of the satelli...

Descripción completa

Guardado en:
Detalles Bibliográficos
Autores principales: Gómes Júnior, A. R., Assafin, M., Braga Ribas, F., Benedetti Rossi, G., Morgado, B. E., Camargo, J. I. B., Vieira Martins, R., Desmars, J., Sicardy, B., Barry, T., Campbell White, J., Fernández Lajús, Eduardo Eusebio, Giles, D., Hanna, Walid, Hayamizu, T., Hirose, T., De Horta, A., Horvat, R., Hosoi, K., Jehin, E., Kerr, S., Machado, D. I., Mammana, Luis Antonio, Maybour, D., Owada, M., Rahvar, S., Snodgrass, C.
Formato: Articulo Preprint
Lenguaje:Inglés
Publicado: 2019
Materias:
Ciencias Astronómicas
Astronomía
occultations
planets
satellites: individual: Phoebe
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/124810
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
Descripción
Sumario:We report six stellar occultations by (Saturn IX) Phoebe, an irregular satellite of Saturn, obtained between mid-2017 and mid-2019. The 2017 July 06 event is 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 over 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 $9.27365 \pm 0.00002$ h. From the stellar occultations, we also obtained 6 geocentric astrometric positions in the ICRS as realised by the Gaia-DR2 with uncertainties at the 1-mas level.

Ejemplares similares