The multichord stellar occultation by the centaur Bienor on January 11, 2019
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Fernández Valenzuela, Estela del Mar; Morales, N.; Vara Lubiano, M.; Ortiz, J. L.; Kretlow, M.; Santos Sanz, Pablo; Román, A.; Alonso Burgos, Sergio; Álvarez Candal, A.; Duffard, René; Casanova, V.; Castro Tirado, Alberto JavierEditorial
EDP
Materia
Kuiper belt: general Minor planets, asteroids: individual: Bienor Planets and satellites: composition Planets and satellites: formation
Date
2023-01-20Referencia bibliográfica
Fernández-Valenzuela, E... [et al.] (2023). The multichord stellar occultation by the centaur Bienor on January 11, 2019. Astronomy & Astrophysics, 669, A112. [https://doi.org/10.1051/0004-6361/202243214]
Sponsorship
European Research Council (ERC) 669416; Space Research Initiative from State of Florida; Spanish grant (MCIU/AEI/FEDER, UE) AYA-2017-84637-R; National Research, Development & Innovation Office (NRDIO) - Hungary K-138962 CAPES-PRINT/UNESP 88887.310463/2018-00 88887.571156/2020-00; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) 427700/2018-3 310683/2017-3 473002/2013-2 314772/2020-0 308150/2016-3 305917/2019-6 150612/2020-6; Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio De Janeiro (FAPERJ) E-26/111.488/2013; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 2018/11239-8; Spanish Government PGC2018-097374-B-I00; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) 001; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ); Fundacao de Apoio a Pesquisa do Distrito Federal (FAPDF) 465376/2014-2; Spanish Government AYA-2017-84637-R SEV-2017-0709; Junta de Andalucia PY20_01309; Agencia Estatal de Investigacion PID2020-112789GB-I00; Fondos de Inversiones de Teruel (FITE)Abstract
Within our program of physical characterization of trans-Neptunian objects and centaurs, we predicted a stellar occultation by the
centaur (54598) Bienor to occur on January 11, 2019, with good observability potential. We obtained high accuracy astrometric data
to refine the prediction, resulting in a shadow path favorable for the Iberian Peninsula. This encouraged us to carry out an occultation
observation campaign that resulted in five positive detections from four observing sites. This is the fourth centaur for which a multichord
(more than two chords) stellar occultation has been observed so far, the other three being (2060) Chiron, (10199) Chariklo, and (95626)
2002 GZ32. From the analysis of the occultation chords, combined with the rotational light curve obtained shortly after the occultation,
we determined that Bienor has an area-equivalent diameter of 150 ± 20 km. This diameter is ∼30 km smaller than the one obtained
from thermal measurements. The position angle of the short axis of the best fitting ellipse obtained through the analysis of the stellar
occultation does not match that of the spin axis derived from long-term photometric models. We also detected a strong irregularity
in one of the minima of the rotational light curve that is present no matter the aspect angle at which the observations were done. We
present different scenarios to reconcile the results from the different techniques. We did not detect secondary drops related to potential
rings or satellites. Nonetheless, similar rings in size to that of Chariklo’s cannot be discarded due to low data accuracy.