Deep Exploration of the Planets HR 8799 b, c, and d with Moderate-resolution Spectroscopy
Ruffio, Jean-Baptiste and Konopacky, Quinn M. and Barman, Travis and Macintosh, Bruce and Hoch, Kielan K. W. and de Rosa, Robert J. and Wang, Jason J. and Czekala, Ian and Marois, Christian (2021) Deep Exploration of the Planets HR 8799 b, c, and d with Moderate-resolution Spectroscopy. Astronomical Journal, 162 (6). Art. No. 290. ISSN 0004-6256. doi:10.3847/1538-3881/ac273a. https://resolver.caltech.edu/CaltechAUTHORS:20211207-393782000
The four directly imaged planets orbiting the star HR 8799 are an ideal laboratory to probe atmospheric physics and formation models. We present more than a decade's worth of Keck/OSIRIS observations of these planets, which represent the most detailed look at their atmospheres to date by its resolution and signal-to-noise ratio. We present the first direct detection of HR 8799 d, the second-closest known planet to the star, at moderate spectral resolution with Keck/OSIRIS (K band; R ≈ 4000). Additionally, we uniformly analyze new and archival OSIRIS data (H and K band) of HR 8799 b, c, and d. First, we show detections of water (H2O) and carbon monoxide (CO) in the three planets and discuss the ambiguous case of methane (CH4) in the atmosphere of HR 8799 b. Then, we report radial-velocity (RV) measurements for each of the three planets. The RV measurement of HR 8799 d is consistent with predictions made assuming coplanarity and orbital stability of the HR 8799 planetary system. Finally, we perform a uniform atmospheric analysis on the OSIRIS data, published photometric points, and low-resolution spectra. We do not infer any significant deviation from the stellar value of the carbon-to-oxygen ratio (C/O) of the three planets, which therefore does not yet yield definitive information about the location or method of formation. However, constraining the C/O for all the HR 8799 planets is a milestone for any multiplanet system, and particularly important for large, widely separated gas giants with uncertain formation processes.
https://doi.org/10.3847/1538-3881/ac273a DOI Article
https://arxiv.org/abs/2109.07614 arXiv Discussion Paper
Ruffio, Jean-Baptiste 0000-0003-2233-4821
Konopacky, Quinn M. 0000-0002-9936-6285
Barman, Travis 0000-0002-7129-3002
Macintosh, Bruce 0000-0003-1212-7538
Hoch, Kielan K. W. 0000-0002-9803-8255
de Rosa, Robert J. 0000-0002-4918-0247
Wang, Jason J. 0000-0003-0774-6502
Czekala, Ian 0000-0002-1483-8811
Marois, Christian 0000-0002-4164-4182
© 2021. The American Astronomical Society. Received 2021 February 9; revised 2021 September 5; accepted 2021 September 14; published 2021 December 6. We would like to thank Karin Öberg for her helpful discussions about planet formation. J.-B.R. acknowledges support from the David and Ellen Lee Prize Postdoctoral Fellowship. The research was supported by grants from NSF, including AST-1411868 (J.-B.R., B.M.) and 1614492 (T.S.B.). Material presented in this work is supported by the National Aeronautics and Space Administration under Grants/Contracts/Agreements No. NNX17AB63G (Q.M.K., T.S.B., and K.K.W.) issued through the Astrophysics Division of the Science Mission Directorate and NNX15AD95G (J.-B.R., R.J.D.R.). Any opinions, findings, and conclusions or recommendations expressed in this work are those of the author(s) and do not necessarily reflect the views of the National Aeronautics and Space Administration. This work benefited from NASA's Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate. This work made use of the sky background models made available by the Gemini observatory 17 . This research has made use of the SVO Filter Profile Service (http://svo2.cab.inta-csic.es/theory/fps/) supported from the Spanish MINECO through grant AYA2017-84089. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We also wish to recognize the very important 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 I (OSIRIS). - Software: astropy 18 (Astropy Collaboration et al. 2013), Matplotlib 19 (Hunter 2007), orbitize! 20 (Blunt et al. 2019), ptemcee 21 (Vousden et al. 2016; Foreman-Mackey et al. 2013), whereistheplanet 22 (Wang et al. 2021).
David and Ellen Lee Postdoctoral Scholarship UNSPECIFIED
NSF AST-1411868
NASA NNX17AB63G
NASA NNX15AD95G
Ministerio de Economía, Industria y Competitividad (MINECO) AYA2017-84089
W. M. Keck Foundation UNSPECIFIED
Heising-Simons Foundation 51 Pegasi b Fellowship
NASA Sagan Fellowship UNSPECIFIED
Extrasolar gaseous giant planets; Exoplanet atmospheric composition; Direct imaging; Exoplanet formation
Classification Code:
Unified Astronomy Thesaurus concepts: Extrasolar gaseous giant planets (509); Exoplanet atmospheric composition (2021); Direct imaging (387); Exoplanet formation (492)
10.3847/1538-3881/ac273a
Jean-Baptiste Ruffio et al 2021 AJ 162 290