Refined physical parameters for Chariklo's body and rings from stellar occultations observed between 2013 and 2020
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The Centaur (10199) Chariklo has the first rings system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow the determination of sizes and shapes with kilometre accuracy and obtain characteristics of the occulting object and its vicinity. Using stellar occultations observed between 2017 and 2020, we aim at constraining Chariklo's and its rings physical parameters. We also determine the rings' structure, and obtain precise astrometrical positions of Chariklo. We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the data sets, from which ingress and egress times, and rings' width and opacity were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo's shape and rings' structure. We characterise Chariklo's ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirmed the detection of W-shaped structures within C1R and an evident variation of radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating ring particle's size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3-sigma), and its width variations may indicate an eccentricity higher than 0.005. We fit a tri-axial shape to Chariklo's detections over eleven occultations and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8, 135.2 and 99.1 km. Ultimately, we provided seven astrometric positions at a milliarcseconds accuracy level, based on Gaia EDR3, and use it to improve Chariklo's ephemeris.
Morgado , B E , Sicardy , B , Braga-Ribas , F , Desmars , J , Gomes-Júnior , A R , Bérard , D , Leiva , R , Ortiz , J L , Vieira-Martins , R , Benedetti-Rossi , G , Santos-Sanz , P , Camargo , J I B , Duffard , R , Rommel , F L , Assafin , M , Boufleur , R C , Colas , F , Kretlow , M , Beisker , W , Sfair , R , Snodgrass , C , Morales , N , Fernández-Valenzuela , E , Amaral , L S , Amarante , A , Artola , R A , Backes , M , Bath , K-L , Bouley , S , Buie , M W , Cacella , P , Colazo , C A , Colque , J P , Dauvergne , J-L , Dominik , M , Emilio , M , Erickson , C , Evans , R , Fabrega-Polleri , J , Garcia-Lambas , D , Giacchini , B L , Hanna , W , Herald , D , Hesler , G , Hinse , T C , Jacques , C , Jehin , E , Jørgensen , U G , Kerr , S , Kouprianov , V , Levine , S E , Linder , T , Maley , P D , Machado , D I , Maquet , L , Maury , A , Melia , R , Meza , E , Mondon , B , Moura , T , Newman , J , Payet , T , Pereira , C L , Pollock , J , Poltronieri , R C , Quispe-Huaynasi , F , Reichart , D , de Santana , T , Schneiter , E M , Sieyra , M V , Skottfelt , J , Soulier , J F , Starck , M , Thierry , P , Torres , P J , Trabuco , L L , Unda-Sanzana , E , Yamashita , T A R , Winter , O C , Zapata , A & Zuluaga , C A 2021 , ' Refined physical parameters for Chariklo's body and rings from stellar occultations observed between 2013 and 2020 ' , Astronomy & Astrophysics . https://doi.org/10.1051/0004-6361/202141543
Astronomy & Astrophysics
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DescriptionFunding: UGJ acknowledges funding from the European Union H2020-MSCA- ITN-2019 under grant no. 860470 (CHAMELEON) and from the Novo Nordisk Foundation Interdisciplinary Synergy Programme grant no. NNF19OC0057374. The following authors acknowledge the respective CNPq grants: BEM 150612/2020-6; FB-R 314772/2020-0; RV-M 304544/2017-f5, 401903/2016-8; JIBC 308150/2016-3 and 305917/2019-6; MA 427700/2018-3, 310683/2017-3, 473002/2013-2. GBR acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016 and CAPES-PRINT/UNESP grant 88887.571156/2020-00, MA FAPERJ grant E-26/111.488/2013 and ARGJr FAPESP grant 2018/11239-8. J.L.O., P.S-S., R.D., and N.M. acknowledge financial support from the State Agency for Researchof the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), from Spanish project AYA2017-89637-R, and from FEDER. P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF” (MCIU/AEI/FEDER, UE). E. Jehin is a Belgian FNRS Senior Research Associate. RS and OCW acknowledge FAPESP grant 2016/24561-0 and CNPq grant 305210/2018-1. TCH acknowledges financial support from the National Research Foundation (NRF; No. 2019R1I1A1A01059609).
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