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Limits on Quaoar's Atmosphere

Fraser, Wesley C. and Trujillo, Chad and Stephens, Andrew W. and Gimeno, German and Brown, Michael E. and Gwyn, Stephen and Kavelaars, J. J. (2013) Limits on Quaoar's Atmosphere. Astrophysical Journal Letters, 774 (2). Art. No. L18. ISSN 2041-8205. doi:10.1088/2041-8205/774/2/L18.

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Here we present high cadence photometry taken by the Acquisition Camera on Gemini South, of a close passage by the ~540 km radius Kuiper belt object, (50000) Quaoar, of a r' = 20.2 background star. Observations before and after the event show that the apparent impact parameter of the event was 0."019 ± 0."004, corresponding to a close approach of 580 ± 120 km to the center of Quaoar. No signatures of occultation by either Quaoar's limb or its potential atmosphere are detectable in the relative photometry of Quaoar and the target star, which were unresolved during closest approach. From this photometry we are able to put constraints on any potential atmosphere Quaoar might have. Using a Markov chain Monte Carlo and likelihood approach, we place pressure upper limits on sublimation supported, isothermal atmospheres of pure N_2, CO, and CH_4. For N_2 and CO, the upper limit surface pressures are 1 and 0.7 μbar, respectively. The surface temperature required for such low sublimation pressures is ~33 K, much lower than Quaoar's mean temperature of ~44 K measured by others. We conclude that Quaoar cannot have an isothermal N_2 or CO atmosphere. We cannot eliminate the possibility of a CH_4 atmosphere, but place upper surface pressure and mean temperature limits of ~138 nbar and ~44 K, respectively.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper DOIArticle
Fraser, Wesley C.0000-0001-6680-6558
Brown, Michael E.0000-0002-8255-0545
Additional Information:© 2013 The American Astronomical Society. Received 2013 June 28; accepted 2013 July 20; published 2013 August 21. The authors thank the Director of the Gemini telescopes for time awarded under the director’s discretion. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).
Funding AgencyGrant Number
National Research Council of CanadaUNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)UNSPECIFIED
Australian Research CouncilUNSPECIFIED
Ministério da Ciência, Tecnologia e InovaçãoUNSPECIFIED
Ministerio de Ciencia, Tecnologıa e Innovacion ProductivaUNSPECIFIED
Subject Keywords:planets and satellites: atmospheres; Kuiper belt objects: individual (Quaoar)
Issue or Number:2
Record Number:CaltechAUTHORS:20131010-101404681
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Official Citation:Limits on Quaoar's Atmosphere Wesley C. Fraser et al. 2013 ApJ 774 L18
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41866
Deposited By: Tony Diaz
Deposited On:10 Oct 2013 18:22
Last Modified:10 Nov 2021 04:35

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