J/A+A/694/A93 X-ray activity of nearby G-, K-, and M-type stars (Zhu+, 2025)
X-ray activity of nearby G-, K-, and M-type stars and implications for
planet habitability around M stars.
Zhu E., Preibisch T.
<Astron. Astrophys. 694, A93 (2025)>
=2025A&A...694A..93Z 2025A&A...694A..93Z (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; X-ray sources; Stars, M-type; Stars, K-type;
Stars, G-type
Keywords: planet-star interactions - stars: activity - stars: coronae -
stars: interiors - stars: late-type - X-rays: stars
Abstract:
The intense X-ray and UV emission of some active M stars has raised
questions about the habitability of planets around M-type stars.
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.
We have constructed volume-complete samples of 205 M stars with
spectral type ≤M6 within 10pc from the Sun, 129 K stars within 16pc,
and 107 G stars within 20pc. We use X-ray data from Chandra,
XMM-Newton, eROSITA, and ROSAT to obtain the X-ray luminosities of the
stars.
Our samples reach an X-ray detection completeness of 85%, 86%, and 80%
for M, K, and G stars. The fractional X-ray 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 spectral type <M4) have
LX/Lbol values that are within the central 80% quantile of the
distribution function for G stars. 55% of all M stars in our sample
(and 72% of the M stars with spectral type <M4) have LX/Lbol less
than 10 times the solar value.
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.
Description:
We have constructed volume-complete samples of 205 M stars with
spectral type ≤M6 within 10pc from the Sun, 129 K stars within 16pc,
and 107 G stars within 20pc. We use X-ray data from Chandra,
XMM-Newton, eROSITA, and ROSAT to obtain the X-ray luminosities of the
stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
g-xray.dat 621 112 X-ray data of nearby G stars (table F1)
k-xray.dat 621 139 X-ray data of nearby K stars (table F1)
m-xray.dat 621 220 X-ray data of nearby M stars (table F1)
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See also:
J/A+A/670/A19 : Fifth Catalogue of Nearby Stars (CNS5) (Golovin+, 2023)
Byte-by-byte Description of file: g-xray.dat k-xray.dat m-xray.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- CNS5 ? Designation in CNS5
8- 14 F7.1 --- GJ ? Gliese-Jahreiss number
16- 32 A17 --- OName Name of stars that do not have CNS5 and GJ
34- 36 A3 --- Comp Component in a multiple system
38- 56 F19.15 deg RAdeg Right ascension (J2000) (Gaia DR3)
58- 76 F19.15 deg DEdeg Declination (J2000) (Gaia DR3)
78 I1 --- fGaia [0/1] Flag for stars with peculiar Gaia
colours
80- 85 A6 --- SpType Spectral type
87-105 A19 --- r_SpType Reference of SpType
113 A1 --- GSpType Spectral type according to MG which is
different from literature SpType
115-131 F17.14 pc Distance Gaia DR3 distance to the Sun
133-153 E21.14 10-7W LXeROSITA ? X-ray luminosity according to eROSITA
155-176 E22.14 10-7W E_LXeROSITA ? Upper error of LXeROSITA
178-199 E22.14 10-7W e_LXeROSITA ? Lower error of LXeROSITA
201-203 F3.1 --- f_LXeROSITA [0/1]? Flag for LXeROSITA as upper limit
value (1 = yes)
205-211 A7 keV BandLXeROSITA Energy band of LXeROSITA
213-231 A19 --- r_LXeROSITA Reference of LXeROSITA
233-254 E22.16 10-7W LXROSAT ? X-ray luminosity according to ROSAT
256-275 E20.14 10-7W E_LXROSAT ? Upper error of LXROSAT
277-296 E20.14 10-7W e_LXROSAT ? Lower error of LXROSAT
298-300 F3.1 --- f_LXROSAT [0/1]? Flag for LXROSAT as upper limit
value (1 = yes)
302-308 A7 keV BandLXROSAT Energy band of LXROSAT
310-313 A4 --- InstLXROSAT Camera of ROSAT used
315-333 A19 --- r_LXROSAT Reference of LXROSAT
335-356 E22.14 10-7W LXother ? X-ray luminosity according to other
telescopes (Chandra or XMM-Newton)
358-378 E21.14 10-7W E_LXother ? Upper error of LXother
380-400 E21.14 10-7W e_LXother ? Lower error of LXother
402-404 F3.1 --- f_LXother [0/1]? Flag for LXother as upper limit
value (1 = yes)
406-412 A7 keV BandLXother Energy band of LXother
414-417 A4 --- InstLXother Camera of other telescopes used
419-437 A19 --- r_LXother Reference of LXother
439-460 E22.16 10-7W LXfinal ? X-ray luminosity used in the analysis,
converted to ROSAT energy band
462-483 E22.16 10-7W E_LXfinal ? Upper error of LXfinal
485-506 E22.16 10-7W e_LXfinal ? Lower error of LXfinal
508-510 F3.1 --- f_LXfinal [0/1]? Flag for LXfinal as upper limit
value (1 = yes)
512-532 E21.15 10-7W Lbol ? Bolometric luminosity
534-552 A19 --- r_Lbol Reference of _bol
554-575 E22.16 --- LX/Lbol ? LX/Lbol used in the final analysis
577-598 E22.16 --- E_LX/Lbol ? Upper error of LX/Lbol
600-621 E22.16 --- e_LX/Lbol ? Lower error of LX/Lbol
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Acknowledgements:
Enyi Zhu, enyi.zhu(at)yahoo.de
(End) Patricia Vannier [CDS] 16-Dec-2024