Hubble WFC3 Spectroscopy of the Habitable-zone Super-Earth LHS 1140 b

Fitting of TESS light curves from LHS 1140 b. Left: detrended light curves and best-fit model. Right: residuals from the fitting.

Atmospheric characterisation of temperate, rocky planets is the holy grail of exoplanet studies. These worlds are at the limits of our capabilities with current instrumentation in transmission spectroscopy and challenge our state-of-the-art statistical techniques.

Here we present the transmission spectrum of the temperate Super-Earth LHS 1140b using the Hubble Space Telescope (HST). The Wide Field Camera 3 (WFC3) G141 grism data of this habitable zone (Teq = 235 K) Super-Earth (R = 1.7 R⊕), shows tentative evidence of water. However, the signal-to-noise ratio, and thus the significance of the detection, is low and stellar contamination models can cause modulation over the spectral band probed.

We attempt to correct for contamination using these models and find that, while many still lead to evidence for water, some could provide reasonable fits to the data without the need for molecular absorption although most of these cause also features in the visible ground-based data which are nonphysical. Future observations with the James Webb Space Telescope (JWST) would be capable of confirming, or refuting, this atmospheric detection.

Billy Edwards, Quentin Changeat, Mayuko Mori, Lara O. Anisman, Mario Morvan, Kai Hou Yip, Angelos Tsiaras, Ahmed Al-Refaie, Ingo Waldmann, Giovanna Tinetti

Comments: Accepted for publication in AJ on 30th October 2020
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2011.08815 [astro-ph.EP] (or arXiv:2011.08815v1 [astro-ph.EP] for this version)
Submission history
From: Billy Edwards
[v1] Tue, 17 Nov 2020 18:25:01 UTC (9,208 KB)
Astrobiology, Astrochemistry,

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