Absence of a Thick Atmosphere on the Terrestrial Exoplanet LHS 3844b
Author
Hu, Renyu
Schaefer, Laura
Deming, Drake
Stevenson, Kevin B.
Dittmann, Jason
Vanderburg, Andrew
Berardo, David
Guo, Xueying
Stassun, Keivan
Crossfield, Ian
Ricker, George
Seager, Sara
Vanderspek, Roland
Koll, Daniel
Morley, Caroline
Published Version
https://doi.org/10.1038/s41586-019-1497-4Metadata
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Laura Kreidberg, Daniel D. B. Koll, Caroline Morley, Renyu Hu, Laura Schaefer, Drake Deming, Kevin B. Stevenson, Jason Dittmann, et al. 2019. Absence of a Thick Atmosphere on the Terrestrial Exoplanet LHS 3844b. Nature 573: 87–90.Abstract
The majority of terrestrial planets in the Galaxy orbit small stars with radii less than 60% that of the Sun1,2. Theoretical models predict that these planets are more vulnerable to at- mospheric escape and collapse than their counterparts orbiting Sun-like stars3–5. To deter- mine whether a thick atmosphere has survived, one approach is to search for signatures of atmospheric heat redistribution in a planet’s thermal phase curve6–9. This technique was previously applied to the super-Earth 55 Cancri e, which showed an offset hot spot indicative of atmosphere heat circulation10. Here we report a phase curve measurement for the exo- planet LHS 3844b, a 1.3 R⊕ world in an 11-hour orbit around a small, nearby star. This is the first such measurement for a planet smaller than 1.6 Re, the size marking the transition from rocky to gaseous worlds11. The phase variation is symmetric and has a large amplitude, implying a dayside brightness temperature of 1040±40 K and a nightside temperature con- sistent with zero K (1σ confidence). The data are best fit by a bare rock model with a low Bond albedo (< 0.2 at 2σ confidence), or a tenuous atmosphere with surface pressure below 0.1 bar. These results support theoretical predictions that hot terrestrial planets orbiting small stars may not retain substantial atmospheres.Terms of Use
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