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Published March 1, 2021 | public
Journal Article

Haze in Pluto's atmosphere: Results from SOFIA and ground-based observations of the 2015 June 29 Pluto occultation

Abstract

On UT 29 June 2015, the occultation by Pluto of a bright star (r′ = 11.9) was observed from the Stratospheric Observatory for Infrared Astronomy (SOFIA) and several ground-based stations in New Zealand and Australia. Pre-event astrometry allowed for an in-flight update to the SOFIA team with the result that SOFIA was deep within the central flash zone (~22 km from center). Analysis of the combined data leads to the result that Pluto's middle atmosphere is essentially unchanged from 2011 and 2013 (Person et al. 2013; Bosh et al. 2015); there has been no significant expansion or contraction of the atmosphere. Additionally, our multi-wavelength observations allow us to conclude that a haze component in the atmosphere is required to reproduce the light curves obtained. This haze scenario has implications for understanding the photochemistry of Pluto's atmosphere.

Additional Information

© 2019 Published by Elsevier Inc. Received 22 October 2019, Accepted 21 November 2019, Available online 30 November 2019. These critical observations with SOFIA would not have been possible if not for more than 30 years of tireless work and genius by the late Professor Dr. Hans-Peter Röser of the University of Stuttgart and by the late SOFIA Chief Engineer Mr. Nans Kunz of the NASA Ames Research Center. The SOFIA portion of these observations would not have occurred without the scientific and management support of then SMO Deputy Director of Science William Reach and then SMO Director Erick Young. We also thank NASA SOFIA Program Manager Eddie Zavala and the entire SOFIA team for their support. We thank Dick French, Georgi Mandushev, Tom Allen, Lauren Biddle, Lisa Prato, and Gail Schaefer for assistance during the prediction phase of this project. JVC would like to thank Ken Bower—"for teaching me the general art of flight planning, and doing an amazing job absorbing the peculiarities of occultation flight planning in two long days before the check flight"; and Navigator Jeff "Elvis" Wilson for smoothly translating our needs into "pilot-speak" with a former bombardier's flair. The FPI+ team thanks Karsten Schindler of DSI for his ground-based observations of the star field prior to the event, allowing accurate planning of the FPI+ settings. This work is based, in part, on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. Additional financial support for this work was provided by NASA through award #SOF 03-0028 issued by USRA. Data were acquired using the Mt. John Observatory Optical Craftsman 61 cm telescope, operated by the AAVSO and the University of Canterbury. We are grateful to Nigel Frost and Arne Henden for support at MJO, and to H. Roe for the loan of his near IR camera (Xeva-CL). Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Laird Close, Katie Morzinski, and Jared Males graciously helped with observations. Partial support for this work was provided by NASA SSO grants NNX15AJ82G to Lowell Observatory, NNX10AB27G to MIT, and NNX12AJ29G to Williams College. AAS acknowledges support from the National Research Foundation of South Africa.

Additional details

Created:
August 22, 2023
Modified:
October 18, 2023