Keck/OSIRIS Paβ High-contrast Imaging and Updated Constraints on PDS 70b

Creators: Uyama, Taichi; Xie, Chen; Aoyama, Yuhiko; Beichman, Charles A.; Hashimoto, Jun; Dong, Ruobing; Hasegawa, Yasuhiro; Ikoma, Masahiro; Mawet, Dimitri; McElwain, Michael W.; Ruffio, Jean-Baptiste; Wagner, Kevin R.; Wang, Jason J.; Zhou, Yifan

Abstract

We present a high-contrast imaging search for Paβ line emission from protoplanets in the PDS 70 system with Keck/OSIRIS integral field spectroscopy. We applied the high-resolution spectral differential imaging technique to the OSIRIS J-band data but did not detect the Paβ line at the level predicted using the parameters of Hashimoto et al. (2020). This lack of Paβ emission suggests the MUSE-based study may have overestimated the line width of Hα. We compared our Paβ detection limits with the previous Hα flux and Hβ limits and estimated A_V to be ∼0.9 and 2.0 for PDS 70 b and c, respectively. In particular, PDS 70 b's A_V is much smaller than implied by high-contrast near-infrared studies, which suggests the infrared-continuum photosphere and the hydrogen-emitting regions exist at different heights above the forming planet.

Additional Information

© 2021. The American Astronomical Society. Received 2021 July 12; revised 2021 August 13; accepted 2021 September 14; published 2021 October 26. We thank Jim Lyke for kindly helping to confirm the OSIRIS FoV settings. The authors would like to thank the anonymous referees for their constructive comments and suggestions to improve the quality of the paper. T.U. is supported by Grant-in-Aid for Japan Society for the Promotion of Science (JSPS) Fellows and JSPS KAKENHI grant No. JP21J01220. Y.H. is supported by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. K.W. acknowledges support from NASA through the NASA Hubble Fellowship grant HST-HF2-51472.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. The results reported herein benefited from collaborations and/or information exchange within NASA's Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate. 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 publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. We wish to acknowledge the critical importance of the current and recent Maunakea Observatories daycrew, technicians, telescope operators, computer support, and office staff employees, especially during the challenging times presented by the COVID-19 pandemic. Their expertize, ingenuity, and dedication is indispensable to the continued successful operation of these observatories. 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. We are most fortunate to have the opportunity to conduct observations from this mountain.

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Accepted Version - 2109.06930.pdf

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