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Atmospheric Monitoring and Precise Spectroscopy of the HR 8799 Planets with SCExAO/CHARIS

Wang, Jason J. and Gao, Peter and Chilcote, Jeffrey and Lozi, Julien and Guyon, Olivier and Marois, Christian and De Rosa, Robert J. and Sahoo, Ananya and Groff, Tyler D. and Vievard, Sébastien and Jovanovic, Nemanja and Greenbaum, Alexandra Z. and Macintosh, Bruce (2022) Atmospheric Monitoring and Precise Spectroscopy of the HR 8799 Planets with SCExAO/CHARIS. Astronomical Journal, 164 (4). Art. No. 143. ISSN 0004-6256. doi:10.3847/1538-3881/ac8984.

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The atmospheres of gas giant planets are thought to be inhomogeneous due to weather and patchy clouds. We present two full nights of coronagraphic observations of the HR 8799 planets using the CHARIS integral field spectrograph behind the SCExAO adaptive optics system on the Subaru Telescope to search for spectrophomometric variability. We did not detect significant variability signals, but placed the lowest variability upper limits for HR 8799c and d. Based on injection-recovery tests, we expected to have a 50% chance to detect signals down to 10% H-band photometric variability for HR 8799c and down to 30% H-band variability for HR 8799d. We also investigated spectral variability and expected a 50% chance to recover 20% variability in the H/K flux ratio for HR 8799c. We combined all the data from the two nights to obtain some of the most precise spectra obtained for HR 8799c, d, and e. Using a grid of cloudy radiative–convective–thermochemical equilibrium models, we found all three planets prefer supersolar metallicity with effective temperatures of ∼1100 K. However, our high signal-to-noise spectra show that HR 8799d has a distinct spectrum from HR 8799c, possibly preferring more vertically extended and uniform clouds and indicating that the planets are not identical.

Item Type:Article
Related URLs:
URLURL TypeDescription
Wang, Jason J.0000-0003-0774-6502
Gao, Peter0000-0002-8518-9601
Chilcote, Jeffrey0000-0001-6305-7272
Lozi, Julien0000-0002-3047-1845
Guyon, Olivier0000-0002-1097-9908
Marois, Christian0000-0002-4164-4182
De Rosa, Robert J.0000-0002-4918-0247
Sahoo, Ananya0000-0003-2806-1254
Groff, Tyler D.0000-0001-5978-3247
Vievard, Sébastien0000-0003-4018-2569
Jovanovic, Nemanja0000-0001-5213-6207
Greenbaum, Alexandra Z.0000-0002-7162-8036
Macintosh, Bruce0000-0003-1212-7538
Additional Information:We thank the anonymous referee for helpful suggestions that improved the manuscript. J.J.W. thanks Jean-Pierre Véran for helpful discussions on atmospheric turbulence. J.J.W. and P.G. were supported by the Heising-Simons Foundation 51 Pegasi b postdoctoral fellowship during the bulk of this research project. CHARIS was built at Princeton University under a Grant-in-Aid for Scientific Research on Innovative Areas from MEXT of the Japanese government (# 23103002) The development of SCExAO was supported by the Japan Society for the Promotion of Science (Grant-in-Aid for Research #23340051, #26220704, #23103002, #19H00703, and #19H00695), the Astrobiology Center of the National Institutes of Natural Sciences, Japan, the Mt. Cuba Astronomical Foundation and the director's contingency fund at Subaru Telescope. The authors 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, and are most fortunate to have the opportunity to conduct observations from this mountain.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Heising-Simons Foundation51 Pegasi b Fellowship
Japan Society for the Promotion of Science (JSPS)23103002
Japan Society for the Promotion of Science (JSPS)23340051
Japan Society for the Promotion of Science (JSPS)26220704
Japan Society for the Promotion of Science (JSPS)23103002
Japan Society for the Promotion of Science (JSPS)19H00703
Japan Society for the Promotion of Science (JSPS)19H00695
National Institutes of Natural Sciences of JapanUNSPECIFIED
Mt. Cuba Astronomical FoundationUNSPECIFIED
Subaru TelescopeUNSPECIFIED
Issue or Number:4
Record Number:CaltechAUTHORS:20220922-931611600.9
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117112
Deposited By: Melissa Ray
Deposited On:27 Sep 2022 20:07
Last Modified:27 Sep 2022 20:07

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