H 2 -dominated Atmosphere as an Indicator of Second-generation Rocky White Dwarf Exoplanets
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Lin_2022_ApJL_925_L10.pdf
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Published version
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2.77 MB
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Author(s)
Lin, Zifan
Seager, Sara
Ranjan, Sukrit
Kozakis, Thea
Kaltenegger, Lisa
Date Issued
2022
Journal
The Astrophysical Journal Letters
Publisher
American Astronomical Society
Citation
Lin, Zifan, Seager, Sara, Ranjan, Sukrit, Kozakis, Thea and Kaltenegger, Lisa. 2022. "H 2 -dominated Atmosphere as an Indicator of Second-generation Rocky White Dwarf Exoplanets." The Astrophysical Journal Letters, 925 (1).
Version
Final published version
Abstract
Abstract
Following the discovery of the first exoplanet candidate transiting a white dwarf (WD), a “white dwarf opportunity” for characterizing the atmospheres of terrestrial exoplanets around WDs is emerging. Large planet-to-star size ratios and hence large transit depths make transiting WD exoplanets favorable targets for transmission spectroscopy; conclusive detection of spectral features on an Earth-like planet transiting a close-by WD can be achieved within a medium James Webb Space Telescope program. Despite the apparently promising opportunity, however, the post-main sequence evolutionary history of a first-generation WD exoplanet has never been incorporated in atmospheric modeling. Furthermore, second-generation planets formed in WD debris disks have never been studied from a photochemical perspective. We demonstrate that transmission spectroscopy can identify a second-generation rocky WD exoplanet with a thick (∼1 bar) H2-dominated atmosphere. In addition, we can infer outgassing activities of a WD exoplanet based on its transmission spectra and test photochemical runaway by studying CH4 buildup.
Following the discovery of the first exoplanet candidate transiting a white dwarf (WD), a “white dwarf opportunity” for characterizing the atmospheres of terrestrial exoplanets around WDs is emerging. Large planet-to-star size ratios and hence large transit depths make transiting WD exoplanets favorable targets for transmission spectroscopy; conclusive detection of spectral features on an Earth-like planet transiting a close-by WD can be achieved within a medium James Webb Space Telescope program. Despite the apparently promising opportunity, however, the post-main sequence evolutionary history of a first-generation WD exoplanet has never been incorporated in atmospheric modeling. Furthermore, second-generation planets formed in WD debris disks have never been studied from a photochemical perspective. We demonstrate that transmission spectroscopy can identify a second-generation rocky WD exoplanet with a thick (∼1 bar) H2-dominated atmosphere. In addition, we can infer outgassing activities of a WD exoplanet based on its transmission spectra and test photochemical runaway by studying CH4 buildup.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution 4.0 International license
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3847/2041-8213/AC4788
