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Evidence for He I 10830 Å Absorption during the Transit of a Warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder

Ninan, Joe P. and Stefansson, Gudmundur and Mahadevan, Suvrath and Bender, Chad and Robertson, Paul and Ramsey, Lawrence and Terrien, Ryan and Wright, Jason and Diddams, Scott A. and Kanodia, Shubham and Cochran, William and Endl, Michael and Ford, Eric B. and Fredrick, Connor and Halverson, Samuel and Hearty, Fred and Jennings, Jeff and Kaplan, Kyle and Lubar, Emily and Metcalf, Andrew J. and Monson, Andrew and Nitroy, Colin and Roy, Arpita and Schwab, Christian (2020) Evidence for He I 10830 Å Absorption during the Transit of a Warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder. Astrophysical Journal, 894 (2). Art. No. 97. ISSN 1538-4357.

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Understanding the dynamics and kinematics of outflowing atmospheres of hot and warm exoplanets is crucial to understanding the origins and evolutionary history of the exoplanets near the evaporation desert. Recently, ground-based measurements of the meta-stable helium atom's resonant absorption at 10830 Å has become a powerful probe of the base environment which is driving the outflow of exoplanet atmospheres. We report evidence for the He I 10830 Å in absorption (equivalent width ~0.012 ± 0.002 Å) in the exosphere of a warm Neptune orbiting the M-dwarf GJ 3470, during three transits using the Habitable Zone Planet Finder near-infrared spectrograph. This marks the first reported evidence for He I 10830 Å atmospheric absorption for a planet orbiting an M-dwarf. Our detected absorption is broad and its blueshifted wing extends to −36 km s⁻¹, the largest reported in the literature to date. We modeled the state of helium atoms in the exosphere of GJ3470b based on assumptions on the UV and X-ray flux of GJ 3470, and found our measurement of flux-weighted column density of meta-stable state helium (N_(He2/3S) = 2.4×10¹⁰cm⁻²), derived from our transit observations, to be consistent with the model, within its uncertainties. The methodology developed here will be useful to study and constrain the atmospheric outflow models of other exoplanets like GJ 3470b, which are near the edge of the evaporation desert.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ninan, Joe P.0000-0001-8720-5612
Stefansson, Gudmundur0000-0001-7409-5688
Mahadevan, Suvrath0000-0001-9596-7983
Bender, Chad0000-0003-4384-7220
Robertson, Paul0000-0003-0149-9678
Terrien, Ryan0000-0002-4788-8858
Wright, Jason0000-0001-6160-5888
Diddams, Scott A.0000-0002-2144-0764
Kanodia, Shubham0000-0001-8401-4300
Cochran, William0000-0001-9662-3496
Endl, Michael0000-0002-7714-6310
Ford, Eric B.0000-0001-6545-639X
Fredrick, Connor0000-0002-0560-1433
Halverson, Samuel0000-0003-1312-9391
Jennings, Jeff0000-0002-7032-2350
Kaplan, Kyle0000-0001-6909-3856
Lubar, Emily0000-0003-0790-7492
Metcalf, Andrew J.0000-0001-5000-1018
Monson, Andrew0000-0002-0048-2586
Nitroy, Colin0000-0001-5747-5064
Roy, Arpita0000-0001-8127-5775
Schwab, Christian0000-0002-4046-987X
Alternate Title:Detection of He I 10830 Å absorption during the transit of a warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder
Additional Information:© 2020 The American Astronomical Society. Received 2019 October 4; revised 2020 March 26; accepted 2020 March 30; published 2020 May 11. The authors wish to thank M. Salz and A. Oklopčić for discussions that contributed to this work. We thank the anonymous referee for a thoughtful reading and suggestions that improved the quality of the manuscript. This work was partially supported by funding from the Center for Exoplanets and Habitable Worlds. The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. We acknowledge support from NSF grants AST-1006676, AST-1126413, AST-1310885, AST-1517592, AST-1310875, the NASA Astrobiology Institute (NAI; NNA09DA76A), PSARC, and NIST in our pursuit of precision radial velocities in the NIR. Computations for this research were performed on the Pennsylvania State University's Institute for CyberScience Advanced CyberInfrastructure (ICS-ACI). We acknowledge support from the Heising-Simons Foundation via grant 2017-0494. This work was supported by NASA Headquarters under the NASA Earth and Space Science Fellowship Program through grants NNX16AO28H and 80NSSC18K1114. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. These results are based on observations obtained with the Habitable-zone Planet Finder Spectrograph on the Hobby–Eberly Telescope. We thank the Resident astronomers and Telescope Operators at the HET for the skillful execution of our observations of our observations with HPF. The Hobby–Eberly Telescope is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximilians-Universität München, and Georg-August Universität Gottingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly. The HET collaboration acknowledges the support and resources from the Texas Advanced Computing Center. This research has made use of NASA's Astrophysics Data System Bibliographic Services. Facility: HET (HPF). - Software: barycorrpy (Kanodia & Wright 2018), astropy (Astropy Collaboration et al. 2018), numpy (van der Walt et al. 2011), scipy (Jones et al. 2001), matplotlib (Hunter 2007), CoCalc (SageMath 2019), GNU parallel (Tange 2011).
Funding AgencyGrant Number
Center for Exoplanets and Habitable WorldsUNSPECIFIED
Pennsylvania State UniversityUNSPECIFIED
Eberly College of ScienceUNSPECIFIED
Pennsylvania Space Grant ConsortiumUNSPECIFIED
Penn State Astrobiology Research Center (PSARC)UNSPECIFIED
National Institute of Standards and Technology (NIST)UNSPECIFIED
Heising-Simons Foundation2017-0494
NASA Earth and Space Science FellowshipNNX16AO28H
Subject Keywords:Exoplanet atmospheric composition ; Exoplanet atmospheres ; Exosphere ; High resolution spectroscopy ; Near infrared astronomy ; Exoplanet astronomy
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanet atmospheric composition (2021); Exoplanet atmospheres (487); Exosphere (499); High resolution spectroscopy (2096); Near infrared astronomy (1093); Exoplanet astronomy (486)
Record Number:CaltechAUTHORS:20191120-092420251
Persistent URL:
Official Citation:Joe P. Ninan et al 2020 ApJ 894 97
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99949
Deposited By: Tony Diaz
Deposited On:20 Nov 2019 17:45
Last Modified:11 May 2020 20:18

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