J/A+A/638/A20 M dwarfs X-ray activity and rotation relations (Magaudda+, 2020)
Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution
of the X-ray luminosity.
Magaudda E., Stelzer B., Covey K.R., Raetz St., Matt S.P., Scholz A.
<Astron. Astrophys. 638, A20 (2020)>
=2020A&A...638A..20M 2020A&A...638A..20M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; X-ray sources ; Stars, masses ; Stars, diameters
Keywords: stars: low-mass - stars: activity - stars: rotation -
stars: magnetic field - X-rays: stars
Abstract:
The relation of activity to rotation in M dwarfs is of high
astrophysical interest because it provides observational evidence of
the stellar dynamo, which is poorly understood for low-mass stars,
especially in the fully convective regime. Previous studies have shown
that the relation of X-ray activity to rotation consists of two
different regimes: the saturated regime for fast-rotating stars and
unsaturated regime for slowly rotating stars. The transition between
the two regimes lies at a rotation period of ∼10d. We present here a
sample of 14 M dwarf stars observed with XMM-Newton and Chandra, for
which we also computed rotational periods from Kepler Two-Wheel (K2)
Mission light curves. We compiled X-ray and rotation data from the
literature and homogenized all data sets to provide the largest
uniform sample of M dwarfs (302 stars) for X-ray activity and rotation
studies to date. We then fit the relation between LX-Prot using three
different mass bins to separate partially and fully convective stars.
We found a steeper slope in the unsaturated regime for fully
convective stars and a nonconstant LX level in the saturated regime
for all masses. In the LX/Lbol-RO space we discovered a remarkable
double gap that might be related to a discontinuous period evolution.
Then we combined the evolution of Prot predicted by angular momentum
evolution models with our new results on the empirical LX-Prot
relation to provide an estimate for the age decay of X-ray luminosity.
We compare predictions of this relationship with the actual X-ray
luminosities of M stars with known ages from 100Myr to a few billion
years. We find remarkably good agreement between the predicted LX and
the observed values for partially convective stars. However, for fully
convective stars at ages of a few billion years, the constructed
LX-age relation overpredicts the X-ray luminosity because the angular
momentum evolution model underpredicts the rotation period of these
stars. Finally, we examine the effect of different parameterizations
for the Rossby number (RO) on the shape of the activity-rotation
relation in LX/Lbol-RO space, and we find that the slope in the
unsaturated regime and the location of the break point of the dual
power-law depend sensitively on the choice of RO.
Description:
Stellar parameters and updated X-ray results computed in this work for
the 288 stars from the literature samples.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 234 288 Stellar parameters and activity-rotation
properties for 288 stars
(updated version, 23/12/2024)
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1 A1 --- Ref Catalogs references (1)
3- 29 A27 --- Name Name of the source from SIMBAD
31- 34 F4.2 mag KsMAG Absolute magnitude in K-band
36- 39 F4.2 mag e_KsMAG Error on the absolute magnitude in K-band
41- 44 F4.2 Msun Mass Stellar mass
46- 49 F4.2 Msun e_Mass Error on stellar mass
51- 54 F4.2 Rsun Radius Stellar radius
56- 59 F4.2 Rsun e_Radius Error on stellar radius
61- 65 F5.2 [Lsun] log(Lbol) Bolometric luminosity from Gaia distance
67- 70 F4.2 [Lsun] log(e_Lbol) Error on the bolometric luminosity
72- 75 F4.2 mag V-J V-J from UCAC4 and 2MASS catalogs
77- 82 F6.2 d Prot Rotational period from K2 lightcurves
84- 88 F5.2 [10-7W] log(LX) X-ray luminosity
90- 93 F4.2 [10-7W] log(e_LX) ?=- Error on the X-ray luminosity
95- 99 F5.2 [-] log(LX/Lbol) X-ray factional luminosity in
logarithmic scale
101-104 F4.2 [-] log(e_LX/Lbol) ?=- Error on the X-ray fractional
luminosity
106-113 F8.6 --- Ro-CS11 ?=- Rossby number from Eq.36 in
Cranmer & Saar, 2011ApJ...741...54C 2011ApJ...741...54C
115-122 F8.6 --- Ro-Brun17 ?=- Rossby number from Eq.33 in
Brun et al., 2017ApJ...836..192B 2017ApJ...836..192B
124-141 F18.16 --- Ro-Wr18 Rossby number from Eq.5 in Wright et al.,
2018MNRAS.479.2351W 2018MNRAS.479.2351W
142-147 F6.2 pc Dist Distance
149-153 F5.2 pc e_Dist Error on distance
155-156 A2 --- FlagGaia Quality flag from Lindegren et al.,
2018A&A...616A...2L 2018A&A...616A...2L and this paper
criteria (2)
158 A1 --- l_log(LX/Lbol) [0/1] Undetected X-ray source (3)
160-187 A28 --- SName Simbad name
188-196 F9.5 deg RAdeg Simbad right ascension (J2000)
198-206 F9.5 deg DEdeg Simbad declination (J2000)
208-210 I3 --- Seq Sequential number
212-234 A23 --- Name2 Common name
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Note (1): Catalogs references as follows:
A = Wright et al, 2011ApJ...743...48W 2011ApJ...743...48W (Cat. J/ApJ/743/48/catalog)
E = Wright & Drake, 2016Natur.535..526W 2016Natur.535..526W
I = Wright et al., 2018MNRAS.479.2351W 2018MNRAS.479.2351W
O = Stelzer et al., 2016MNRAS.463.1844S 2016MNRAS.463.1844S (Cat. J/MNRAS/463/1844)
U = Gonzalez-Alvarez et al., 2019A&A...624A..27G 2019A&A...624A..27G
Note (2): The first digit recalls the quality criteria in Appendix C of
Lindegren et al., 2018A&A...616A...2L 2018A&A...616A...2L, the second digit recalls the quality
criteria as explained in Sect. 3 of the current paper as follows:
11 = Gaia distance are reliable. Stellar parameters and the X-ray
luminosity are computed with Gaia distance
10 = Gaia distances are not reliable and stellar parameters and the X-ray
luminosity are computed with the photometric distance
01 = Gaia distances are not reliable and stellar parameters and the X-ray
luminosity are computed with the photometric distance
00 = Gaia distances are not reliable and stellar parameters and the X-ray
luminosity are computed with the photometric distance
Note (3): Undetected X-ray source as follows:
0 = the source is well detected by the satellite
1 = the source not detected by the satellite and we derive LX and LX/Lbol
as upper limits
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Acknowledgements:
Enza Magaudda, magaudda(at)astro.uni-tuebingen.de
History:
03-Jun-2020: on-line version
23-Dec-2024: corrected version
(End) Patricia Vannier [CDS] 03-Apr-2020