X-ray Activity Of Nearby G-, K-, And M-type Stars And Implications for Planet Habitability Around M stars
Context. The intense X-ray and UV emission of some active M stars has raised questions about the habitability of planets around M-type stars. Aims. We aim to determine the unbiased distribution of X-ray luminosities in complete, volume-limited samples of nearby M dwarfs, and compare them to those of K and G dwarfs. Methods.
We constructed volume-complete samples of 205 M stars with a spectral type ≤ M6 within 10 pc of the Sun, 129 K stars within 16 pc, and 107 G stars within 20 pc. We used X-ray data from Chandra, XMM-Newton, eROSITA, and ROSAT to obtain the X-ray luminosities of the stars.
Results. Our samples reach an X-ray detection completeness of 85%, 86%, and 80% for M, K, and G stars, respectively. The fractional X-ray luminosities relative to the bolometric luminosities, log(LX/Lbol), of the M stars show a bimodal distribution, with one peak at around -5, mostly contributed by early M stars (M0–M4), and another peak around -3.5, contributed mainly by M4–M6 stars.
The comparison of the different spectral classes shows that 63% of all M stars in our sample (80% of the M stars with a spectral type < M4) have LX/Lbol values that are within the central 80% quantile of the distribution function for G stars. In addition, 55% of all M stars in our sample (and 72% of the M stars with a spectral type < M4) have LX/Lbol less than 10 times the solar value.
Conclusions. The X-ray activity levels of the majority (≥60%) of nearby M dwarfs no later than M6 are actually not higher than the typical (80% quantile) levels for G-type stars. The X-ray irradiation of habitable-zone planets around these stars should therefore not present a specific problem for their habitability.
E. Zhu, T. Preibisch
Comments: 18 pages, 11 figures, 6 tables, accepted for publication in A&A
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); High Energy Astrophysical Phenomena (astro-ph.HE)
Cite as: arXiv:2501.07313 [astro-ph.SR] (or arXiv:2501.07313v1 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2501.07313
Focus to learn more
Submission history
From: Enyi Zhu
[v1] Mon, 13 Jan 2025 13:25:18 UTC (4,382 KB)
https://arxiv.org/abs/2501.07313
Astrobiology,
