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Detection and Bulk Properties of the HR 8799 Planets with High-resolution Spectroscopy

Wang, Jason J. and Ruffio, Jean-Baptiste and Morris, Evan and Delorme, Jacques-Robert and Jovanovic, Nemanja and Pezzato, Jacklyn and Echeverri, Daniel and Finnerty, Luke and Hood, Callie and Zanazzi, J. J. and Bryan, Marta L. and Bond, Charlotte Z. and Cetre, Sylvain and Martin, Emily C. and Mawet, Dimitri and Skemer, Andy and Baker, Ashley and Xuan, Jerry W. and Wallace, J. Kent and Wang, Ji and Bartos, Randall and Blake, Geoffrey A. and Boden, Andy and Buzard, Cam and Calvin, Benjamin and Chun, Mark and Doppmann, Greg and Dupuy, Trent J. and Duchêne, Gaspard and Feng, Y. Katherina and Fitzgerald, Michael P. and Fortney, Jonathan and Freedman, Richard S. and Knutson, Heather and Konopacky, Quinn and Lilley, Scott and Liu, Michael C. and Lopez, Ronald and Lupu, Roxana and Marley, Mark S. and Meshkat, Tiffany and Miles, Brittany and Millar-Blanchaer, Maxwell and Ragland, Sam and Roy, Arpita and Ruane, Garreth and Sappey, Ben and Schofield, Tobias and Weiss, Lauren and Wetherell, Edward and Wizinowich, Peter and Ygouf, Marie (2021) Detection and Bulk Properties of the HR 8799 Planets with High-resolution Spectroscopy. Astronomical Journal, 162 (4). Art. No. 148. ISSN 0004-6256. doi:10.3847/1538-3881/ac1349. https://resolver.caltech.edu/CaltechAUTHORS:20210831-203938762

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Abstract

Using the Keck Planet Imager and Characterizer, we obtained high-resolution (R ∼ 35,000) K-band spectra of the four planets orbiting HR 8799. We clearly detected H2O and CO in the atmospheres of HR 8799 c, d, and e, and tentatively detected a combination of CO and H2O in b. These are the most challenging directly imaged exoplanets that have been observed at high spectral resolution to date when considering both their angular separations and flux ratios. We developed a forward-modeling framework that allows us to jointly fit the spectra of the planets and the diffracted starlight simultaneously in a likelihood-based approach and obtained posterior probabilities on their effective temperatures, surface gravities, radial velocities, and spins. We measured v sin(i) values of 10.1^(+2.8)_(-2.7) km s⁻¹ for HR 8799 d and 15.0^(+2.3)_(-2.6) km s⁻¹ for HR 8799 e, and placed an upper limit of <14 km s⁻¹ of HR 8799 c. Under two different assumptions of their obliquities, we found tentative evidence that rotation velocity is anticorrelated with companion mass, which could indicate that magnetic braking with a circumplanetary disk at early times is less efficient at spinning down lower-mass planets.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-3881/ac1349arXivArticle
https://arxiv.org/abs/2107.06949arXivDiscussion Paper
ORCID:
AuthorORCID
Wang, Jason J.0000-0003-0774-6502
Ruffio, Jean-Baptiste0000-0003-2233-4821
Delorme, Jacques-Robert0000-0001-8953-1008
Jovanovic, Nemanja0000-0001-5213-6207
Echeverri, Daniel0000-0002-1583-2040
Finnerty, Luke0000-0002-1392-0768
Hood, Callie0000-0003-1150-7889
Zanazzi, J. J.0000-0002-9849-5886
Bryan, Marta L.0000-0002-6076-5967
Martin, Emily C.0000-0002-0618-5128
Mawet, Dimitri0000-0002-8895-4735
Skemer, Andy0000-0001-6098-3924
Xuan, Jerry W.0000-0002-6618-1137
Wallace, J. Kent0000-0001-5299-6899
Wang, Ji0000-0002-4361-8885
Blake, Geoffrey A.0000-0003-0787-1610
Buzard, Cam0000-0002-9943-6124
Calvin, Benjamin0000-0003-4737-5486
Chun, Mark0000-0002-8462-0703
Dupuy, Trent J.0000-0001-9823-1445
Duchêne, Gaspard0000-0002-5092-6464
Fitzgerald, Michael P.0000-0002-0176-8973
Fortney, Jonathan0000-0002-9843-4354
Knutson, Heather0000-0002-0822-3095
Konopacky, Quinn0000-0002-9936-6285
Liu, Michael C.0000-0003-2232-7664
Marley, Mark S.0000-0002-5251-2943
Meshkat, Tiffany0000-0001-6126-2467
Miles, Brittany0000-0002-5500-4602
Millar-Blanchaer, Maxwell0000-0001-6205-9233
Ragland, Sam0000-0002-0696-1780
Roy, Arpita0000-0001-8127-5775
Ruane, Garreth0000-0003-4769-1665
Weiss, Lauren0000-0002-3725-3058
Wizinowich, Peter0000-0002-1646-442X
Ygouf, Marie0000-0001-7591-2731
Additional Information:© 2021. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 April 20; revised 2021 June 18; accepted 2021 July 9; published 2021 September 17. We thank Sivan Ginzburg, Konstantin Batygin, and Eve Lee for useful discussions. We thank the Keck staff for helping support the deployment of KPIC during the global pandemic. J.J.W. is supported by the Heising-Simons Foundation 51 Pegasi b Fellowship. This work was supported by the Heising-Simons Foundation through grants #2015-129, #2017-318, and #2019-1312. This work was supported by the Simons Foundation. E.C.M. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1801978. Part of the computations presented here were conducted on the Caltech High Performance Cluster, partially supported by a grant from the Gordon and Betty Moore Foundation. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Data presented in this work 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. We wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facility: Keck (KPIC). - Software: astropy (Astropy Collaboration et al. 2018), scipy (Virtanen et al. 2020), PyAstronomy (Czesla et al. 2019), pymultinest (Buchner et al. 2014), dynesty (Speagle 2020), whereistheplanet (Wang et al. 2021), corner (Foreman-Mackey 2016).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
Heising-Simons Foundation51 Pegasi b Fellowship
Heising-Simons Foundation2015-129
Heising-Simons Foundation2017-318
Heising-Simons Foundation2019-1312
Simons FoundationUNSPECIFIED
NSF Astronomy and Astrophysics FellowshipAST-1801978
Gordon and Betty Moore FoundationUNSPECIFIED
NASA/JPL/CaltechUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Exoplanet atmospheres; Exoplanet formation; High angular resolution; High resolution spectroscopy
Issue or Number:4
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanet atmospheres (487); Exoplanet formation (492); High angular resolution (2167); High resolution spectroscopy (2096)
DOI:10.3847/1538-3881/ac1349
Record Number:CaltechAUTHORS:20210831-203938762
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210831-203938762
Official Citation:Jason J. Wang et al 2021 AJ 162 148
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110657
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:01 Sep 2021 14:18
Last Modified:20 Sep 2021 18:30

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