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Non-detection of He I in the Atmosphere of GJ 1214b with Keck/NIRSPEC, at a Time of Minimal Telluric Contamination

Spake, Jessica J. and Oklopčić, A. and Hillenbrand, L. A. and Knutson, Heather A. and Kasper, David and Dai, Fei and Orell-Miquel, Jaume and Vissapragada, Shreyas and Zhang, Michael and Bean, Jacob L. (2022) Non-detection of He I in the Atmosphere of GJ 1214b with Keck/NIRSPEC, at a Time of Minimal Telluric Contamination. Astrophysical Journal Letters, 939 (1). Art. No. L11. ISSN 2041-8205. doi:10.3847/2041-8213/ac88c9.

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Observations of helium in exoplanet atmospheres may reveal the presence of large gaseous envelopes and indicate ongoing atmospheric escape. Orell-Miquel et al. (2022) used CARMENES to measure a tentative detection of helium for the sub-Neptune GJ 1214b, with a peak excess absorption reaching over 2% in-transit depth at 10830 Å. However, several non-detections of helium had previously been reported for GJ 1214b. One explanation for the discrepancy was contamination of the planetary signal by overlapping telluric absorption and emission lines. We used Keck/NIRSPEC to observe another transit of GJ 1214b at 10830 Å at a time of minimal contamination by telluric lines, and did not observe planetary helium absorption. Accounting for correlated noise in our measurement, we place an upper limit on the excess absorption size of 1.22% (95% confidence). We find that the discrepancy between the CARMENES and NIRSPEC observations is unlikely to be caused by using different instruments or stellar activity. It is currently unclear whether the difference is due to correlated noise in the observations, or variability in the planetary atmosphere.

Item Type:Article
Related URLs:
URLURL TypeDescription
Spake, Jessica J.0000-0002-5547-3775
Oklopčić, A.0000-0002-9584-6476
Knutson, Heather A.0000-0002-5375-4725
Kasper, David0000-0003-0534-6388
Dai, Fei0000-0002-8958-0683
Orell-Miquel, Jaume0000-0003-2066-8959
Vissapragada, Shreyas0000-0003-2527-1475
Zhang, Michael0000-0002-0659-1783
Bean, Jacob L.0000-0003-4733-6532
Additional Information: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. 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. We are deeply grateful to the WMKO support astronomers, Carlos Alvarez and Greg Doppmann, who provided exceptional support during this observing program, which occurred soon after the NIRSPEC upgrade. Facility: Keck:II (NIRSPEC). Software: SciPy (Virtanen et al. 2020); NumPy (Van Der Walt et al. 2011); matplotlib (Hunter 2007); Astropy (Astropy Collaboration et al. 2013).
Group:Astronomy Department, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20221109-552977300.3
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117802
Deposited By: Research Services Depository
Deposited On:18 Nov 2022 21:47
Last Modified:19 Nov 2022 00:07

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