Exoplanetology: Exoplanets & Exomoons

Potential For Life To Exist And Be Detected On Earth-like Planets Orbiting White Dwarfs

By Keith Cowing

Status Report

astro-ph.EP

December 2, 2024

Filed under astro-ph.EP, atmosphere, biosignature, Earthlike planet, exoplanet, habitability, Habitable Zone, JWST, Photosynthesis, prebiotic chemistry, temperate rocky planet, white dwarf

Potential For Life To Exist And Be Detected On Earth-like Planets Orbiting White Dwarfs — Habitable zone for a white dwarf (blue region) at ages of 2, 6, and 10 Gyr compared to the habitable zone of the red dwarf TRAPPIST-1 (orange region). The inset shows the size comparison of a typical 0.6M⊙ white dwarf (cyan region) to that of TRAPPIST-1 (pink region). The optimistic habitable zone for TRAPPIST-1 is calculated from the recent Venus and early Mars limits from Kopparapu et al. (2013) using the luminosity and effective temperature from Van Grootel et al. (2018). The magenta region specifies where overlap of the two habitable zones occurs. The dashed black line shows the orbital radius at which an Earth-like planet around a 0.6M⊙ white dwarf stays in the habitable zone for the maximum amount of time (i.e., maximum habitable lifetime), and the dashed red line shows the Roche limit (i.e., tidal disruption limit) for such a system. — astro-ph.EP

With recent observations confirming exoplanets orbiting white dwarfs, there is growing interest in exploring and quantifying the habitability of temperate rocky planets around white dwarfs.

In this work, the limits of the habitable zone of an Earth-like planet around a white dwarf are computed based on the incident stellar flux, and these limits are utilized to assess the duration of habitability at a given orbital distance. For a typical 0.6M_⊙ white dwarf an Earth-like planet at ∼0.012 AU could remain in the temporally evolving habitable zone, maintaining conditions to support life, for nearly 7 Gyr.

In addition, additional constraints on habitability are studied for the first time by imposing the requirement of receiving sufficient photon fluxes for UV-mediated prebiotic chemistry and photosynthesis.

We demonstrate that these thresholds are comfortably exceeded by planets in the habitable zone. The prospects for detecting atmospheric biosignatures are also evaluated, and shown to require integration times on the order of one hour or less for ongoing space observations with JWST.

Caldon T. Whyte, L. H. Quiroga-Nuñez, Manasvi Lingam, Paola Pinilla

Comments: Accepted for publication in ApJ Letters; 15 pages; 3 figures; 1 table
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2411.18934 [astro-ph.EP] (or arXiv:2411.18934v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2411.18934
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Related DOI:
https://doi.org/10.3847/2041-8213/ad9821
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Submission history
From: Caldon Whyte
[v1] Thu, 28 Nov 2024 05:53:44 UTC (387 KB)
https://arxiv.org/abs/2411.18934
Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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