Abstract We present the detection of neutral helium at 10833 Å in the atmosphere of WASP-52b and tentative evidence of helium in the atmosphere of the grazing WASP-177b, using high-resolution observations acquired with the NIRSPEC instrument on the Keck II telescope. We detect excess absorption by helium in WASP-52b’s atmosphere of 3.44% ± 0.31% (11 σ ), or equivalently 66 ± 5 atmospheric scale heights. This absorption is centered on the planet’s rest frame (Δ v = 0.00 ± 1.19 km s −1 ). We model the planet’s escape using a 1D Parker wind model and calculate its mass-loss rate to be ∼1.4 × 10 11 g s −1 , or equivalently 0.5% of its mass per gigayear. For WASP-177b, we see evidence for redshifted (Δ v = 6.02 ± 1.88 km s −1 ) helium-like absorption of 1.28% ± 0.29% (equal to 23 ± 5 atmospheric scale heights). However, due to residual systematics in the transmission spectrum of similar amplitude, we do not interpret this as significant evidence for He absorption in the planet’s atmosphere. Using a 1D Parker wind model, we set a 3 σ upper limit on WASP-177b’s escape rate of 7.9 × 10 10 g s −1 . Our results, taken together with recent literature detections, suggest the tentative relation between XUV irradiation and He i absorption amplitude may be shallower than previously suggested. Our results highlight how metastable helium can advance our understanding of atmospheric loss and its role in shaping the exoplanet population.
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Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultranarrowband Photometry
- Award ID(s):
- 1852268
- NSF-PAR ID:
- 10250322
- Date Published:
- Journal Name:
- The Astronomical Journal
- Volume:
- 159
- Issue:
- 6
- ISSN:
- 1538-3881
- Page Range / eLocation ID:
- 278
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3847/1538-3881/ab8e34
