J/A+A/673/L4 The two rings of (50000) Quaoar (Pereira+, 2023)
The two rings of (50000) Quaoar.
Pereira C.L., Sicardy B., Morgado B.E., Braga-Ribas F.,
Fernandez-Valenzuela E., Souami D., Holler B.J., Boufleur R.C., Margoti G.,
Assafin M., Ortiz J.L., Santos-Sanz P., Epinat B., Kervella P., Desmars J.,
Vieira-Martins R., Kilic Y., Gomes Junior A.R., Camargo J.I.B., Emilio M.,
Vara-Lubiano M., Kretlow M., Albert L., Alcock C., Ball J.G., Bender K.,
Buie M.W., Butterfield K., Camarca M., Castro-Chacon J.H., Dunford R.,
Fisher R.S., Gamble D., Geary J.C., Gnilka C.L., Green K.D., Hartman Z.D.,
Huang C.-K., Januszewski H., Johnston J., Kagitani M., Kamin R.,
Kavelaars J.J., Keller J.M., de Kleer K.R., Lehner M.J., Luken A.,
Marchis F., Marlin T., McGregor K., Nikitin V., Nolthenius R., Patrick C.,
Redfield S., Rengstorf A.W., Reyes-Ruiz M., Seccull T., Skrutskie M.F.,
Smith A.B., Sproul M., Stephens A.W., Szentgyorgyi A., Sanchez-Sanjuan S.,
Tatsumi E., Verbiscer A., Wang S.-Y., Yoshida F., Young R., Zhang Z.-W.
<Astron. Astrophys. 673, L4 (2023)>
=2023A&A...673L...4P 2023A&A...673L...4P (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Occultations ; Photometry ; Optical
Keywords: methods: data analysis - methods: observational -
techniques: photometric - Kuiper belt objects: individual: Quaoar -
planets and satellites: rings
Abstract:
Quaoar is a classical trans-Neptunian object (TNO) with an
area-equivalent diameter of 1100 km and an orbital semi-major axis of
43.3 astronomical units. Based on stellar occultations observed
between 2018 and 2021, an inhomogeneous ring (Q1R, i.e., Quaoar's
first ring) has been detected around this body.
A new stellar occultation by Quaoar was observed on August 9, 2022,
with the aim of improving Quaoar's shape models and the physical
parameters of Q1R, while searching for additional material around the
body.
The occultation provided nine effective chords across Quaoar, pinning
down its size, shape, and astrometric position. Large facilities, such
as Gemini North and the Canada-France-Hawaii Telescope (CFHT), were
used to obtain high acquisition rates and signal-to-noise ratios. The
light curves were also used to characterize the Q1R ring (radial
profiles and orbital elements).
Quaoar's elliptical fit to the occultation chords yields the limb with
an apparent semi-major axis of 579.5±4.0km, apparent oblateness of
0.12±0.01, and area-equivalent radius of 543±2km. Quaoar's limb
orientation is consistent with Q1R and Weywot orbiting in Quaoar's
equatorial plane. The orbital radius of Q1R is refined to a value of
4057±6km. The radial opacity profile of the more opaque ring
profile follows a Lorentzian shape that extends over 60 km, with a
full width at half maximum (FWHM) of ∼5km and a peak normal optical
depth of 0.4. Besides the secondary events related to the already
reported rings, new secondary events detected during the August 2022
occultation in three different data sets are consistent with another
ring around Quaoar with a radius of 2520±20km, assuming the ring
is circular and co-planar with Q1R. This new ring has a typical width
of 10km and a normal optical depth of ∼0.004. Just as Q1R, it also
lies outside Quaoar's classical Roche limit.
Description:
Light flux of the occulted star plus the occulting object during the
stellar occultation for each observer, also the best fitted model and
their residuals.
objects:
-------------------------------------------------------------------
Planet Name H i e a
mag deg AU
-------------------------------------------------------------------
50000 Quaoar 2.51 7.990425 0.04154574 43.64120180
-------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 108 23 List of light curves
lc/* . 23 Individual light curves
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See also:
J/A+A/664/L15 : Quaoar's stellar occultation observed by CHEOPS (Morgado+ 2022)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 25 A25 --- FileName Name of the light curve file in subdirectory lc
28-108 A81 --- Title Title of the file
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Byte-by-byte Description of file: lc/*
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Bytes Format Units Label Explanations
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1- 16 F16.8 d JD Julian date of mid-exposure observation
18- 31 F14.8 s Time Seconds relative to 2022-08-09 00:00:00.000 UTC
33- 43 F11.8 --- Fobs Normalised observed flux
45- 55 F11.8 --- Ffit Normalised best fitted modelled flux
57- 67 F11.8 --- O-C Residual O-C
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History:
From Chrystian Luciano Pereira, chryslp.fis(at)gmail.com
Acknowledgements:
C.L.P is thankful for the support of the CAPES and FAPERJ/DSC-10
(E26/204.141/2022). This work was carried out within the "Lucky
Star" umbrella that agglomerates the efforts of the Paris, Granada,
and Rio teams, funded by the European Research Council under the
European Community's H2020 (ERC Grant Agreement No. 669416). This
study was financed in part by the National Institute of Science and
Technology of the e-Universe project (INCT do e-Universo, CNPq grant
465376/2014-2). This study was financed in part by CAPES - Finance
Code 001. The following authors acknowledge the respective CNPq
grants: B.E.M. 150612/2020-6; F.B.R. 314772/2020-0; R.V.M.
307368/2021-1; M.A. 427700/2018-3, 310683/2017-3, 473002/2013-2;
J.I.B.C. 308150/2016-3, 305917/2019-6. R.C.B acknowledge the FAPERJ
grant E26/202.125/2020. E.F.-V. acknowledges financial support from
the Florida Space Institute and the Space Research Initiative. J.L.O.,
P.S-S., M.V-L, and M. K. acknowledge financial support from the grant
CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, they also
acknowledge the financial support by the Spanish grants
PID2020-112789GB-I00 from AEI and Proyecto de Excelencia de la Junta
de Andalucia PY20-01309. Funding for RECON was provided by grants
from USA: NSF AST-1413287, AST-1413072, AST-1848621, and AST-1212159.
We thank RECON observers Doug Thompson, Ken Conway, Dorey Conway,
Terry Miller, David Schulz, Michael von Schalscha, and Matt
Christensen for their efforts in collecting data. Based on
observations obtained with WIRCam, a joint project of CFHT, Taiwan,
Korea, Canada, France, at the Canada-France-Hawaii Telescope (CFHT)
which is operated from the summit of Maunakea by the National Research
Council of Canada, the Institut National des Sciences de l'Univers of
the Centre National de la Recherche Scientifique of France, and the
University of Hawaii. The observations at the Canada-France-Hawaii
Telescope were performed with care and respect from the summit of
Maunakea which is a significant cultural and historic site. We thank
Marc Baril and Tom Vermeulen for their time dedicated to the
observation performed at Canada-France-Hawaii Telescope (CFHT). Based
on observations obtained at the international Gemini Observatory, a
program of NSF's NOIRLab, which is managed by the Association of
Universities for Research in Astronomy (AURA) under a cooperative
agreement with the National Science Foundation on behalf of the Gemini
Observatory partnership: the National Science Foundation (United
States), National Research Council (Canada), Agencia Nacional de
Investigacion y Desarrollo (Chile), Ministerio de Ciencia, Tecnologia
e Innovacion (Argentina), Ministerio da Ciencia, Tecnologia, Inovacoes
e Comunicacoes (Brazil), and Korea Astronomy and Space Science
Institute (Republic of Korea). This work made use of data from
GN-2022B-DD-101 observing program and were obtained with the
High-Resolution Imaging instrument(s) 'Alopeke (and/or Zorro).
'Alopeke (and/or Zorro) was funded by the NASA Exoplanet Exploration
Program and built at the NASA Ames Research Center by Steve B. Howell,
Nic Scott, Elliott P. Horch, and Emmett Quigley. 'Alopeke (and/or
Zorro) was mounted on the Gemini North (and/or South) telescope of the
international Gemini Observatory, a program of NSF's NOIRLab, which is
managed by the Association of Universities for Research in Astronomy
(AURA) under a cooperative agreement with the National Science
Foundation. This work was enabled by observations made from the Gemini
North telescope, located within the Maunakea Science Reserve and
adjacent to the summit of Maunakea. We are grateful for the privilege
of observing the Universe from a place that is unique in both its
astronomical quality and its cultural significance. This research used
sora, a python package for stellar occultations reduction and
analysis, developed with the support of ERC Lucky Star and
LIneA/Brazil, within the collaboration of Rio-Paris-Granada teams.This
work profited from unpublished occultations by Quaoar made at SOAR
(SO2019A-003) and the Pico dos Dias Observatory (OP2019A-004) to
improve the accuracy of the ephemeris NIMAv16.
(End) Patricia Vannier [CDS] 09-May-2023