J/A+A/661/A29 First eROSITA study of nearby M dwarfs (Magaudda+, 2022)
First eROSITA study of nearby M dwarfs and the rotation-activity relation in
combination with TESS.
Magaudda E., Stelzer B., Raetz St., Klutsch A., Salvato M., Wolf J.
<Astron. Astrophys. 661, A29 (2022)>
=2022A&A...661A..29M 2022A&A...661A..29M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type; X-ray sources
Keywords: stars: low-mass - stars: activity - stars: rotation -
stars: magnetic field - X-rays: stars
Abstract:
We present the first results with the ROentgen Survey with an Imaging
Telescope Array (eROSITA) on board the Russian Spektrum-Roentgen-Gamma
mission (SRG), and we combine the new X-ray data with observations
with the Transiting Exoplanet Survey Satellite (TESS). We use the
superblink proper motion catalog of nearby M dwarfs as input sample to
search for eROSITA and TESS data. We extracted Gaia-DR2 data for the
full M dwarf catalog that comprises ∼9000 stars, and we calculated the
stellar parameters from empirical relations with optical/IR colors.
Then we cross-matched this catalog with the eROSITA Final Equatorial
Depth Survey (eFEDS) and the first eROSITA all-sky survey (eRASS1).
After a meticulous source identification in which we associate the
closest Gaia source to the eROSITA X-ray detections, our sample of M
dwarfs is defined by 687 stars with SpT = K5..M7 (673 from eRASS1 and
14 from eFEDS). While for eRASS1 we used the data from the source
catalog provided by the eROSITA_DE consortium, for the much smaller
eFEDS sample we performed the data extraction and we analyzed the
X-ray spectra and light curves.
This unprecedented data base for X-ray emitting M dwarfs allowed us to
put a quantitative constraint on the mass dependence of the X-ray
luminosity, and to determine the change in the activity level with
respect to pre-main-sequence stars. TESS observations are available
for 489 of 687 X-ray detected M dwarfs, and applying standard period
search methods we could determine the rotation period for 180 X-ray
detected M dwarfs, about one forth of the X-ray sample. With the joint
eROSITA and TESS sample, and combining it with our compilation of
historical X-ray and rotation data for M dwarfs, we examine the mass
dependence of the "saturated" regime of the rotation-activity
relation. A first comparison of eROSITA hardness ratios and spectra
shows that 65% of the X-ray detected M dwarfs have coronal
temperatures of ∼0.5keV. We performed a statistical investigation of
the long-term X-ray variability of M dwarfs comparing the eROSITA
measurements to those obtained ∼30 years earlier during the ROSAT
all-sky survey (RASS). Evidence for X-ray flares are found in various
parts of our analysis: directly from an inspection of the eFEDS light
curves, in the relation between RASS and eRASS1 X-ray luminosities,
and in a subset of stars that displays X-ray emission hotter than the
bulk of the sample according to the hardness ratios. Finally, we point
out the need to obtain X-ray spectroscopy for more M dwarfs to study
the coronal temperature-luminosity relation that is not well
constrained by our eFEDS results.
Description:
The M dwarfs catalog based on new eROSITA and TESS data containing 687
stars. Stellar parameters, astrometric data, X-ray and photometric
data are calculated and collected in these tables. The sources have a
limiting Gaia-DR2 distance Dist<130pc and 1.3mag≤Gbp-Grp≤4.4mag.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables.dat 223 687 Stellar parameters and distances (table 2),
X-ray parameters (table 3) and
X-ray activity and rotation (table 5)
(updated version, 23/12/2024)
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/347 : Distances to 1.33 billion stars in Gaia DR2
(Bailer-Jones+, 2018)
J/AJ/142/138 : All-sky catalog of bright M dwarfs (Lepine+, 2011)
J/A+A/588/A103 : Second ROSAT all-sky survey (2RXS) source catalog
(Boller+, 2016)
J/A+A/661/A1 : The eFEDS X-ray catalogs (V7.4) (Brunner+, 2022)
J/A+A/661/A2 : Galaxy clusters and groups in eFEDS (Liu+, 2022)
J/A+A/661/A3 : eFEDS counterparts to point-like sources (Salvato+, 2022)
J/A+A/661/A4 : eFEDS optical cluster and group catalog (Klein+, 2022)
J/A+A/661/A5 : The eFEDS AGN catalog (Liu+, 2022)
J/A+A/661/A7 : X-ray properties of eFEDS clusters and groups (Bahar+, 2022)
J/A+A/661/A8 : eFEDS catalogue of variable X-ray sources (Boller+, 2022)
J/A+A/661/A10 : eFEDS galaxy clusters and groups in disguise (Bulbul+, 2022)
J/A+A/661/A23 : Exoplanet X-ray irradiation & evaporation rates (Foster+, 2022)
J/A+A/661/A24 : Corona-chromosphere connection (Fuhrmeister+, 2022)
J/A+A/661/A34 : eta Cha cluster eROSITA X-ray scan (Robrade+, 2022)
J/A+A/661/A35 : eROSITA study of 47 Tuc globular cluster (Saeedi+, 2022)
J/A+A/661/A38 : SRG/ART-XC 1st year all-sky X-ray survey (Pavlinsky+, 2022)
J/A+A/661/A40 : eRASS1 X-ray sources Sco-Cen members (Schmitt+, 2022)
J/A+A/661/A44 : A first eROSITA view of ultracool dwarfs (Stelzer+, 2022)
Byte-by-byte Description of file: tables.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number
5- 20 A16 --- LG11Name Source Name, PM IHHMMSS+DDMMAA (1)
22- 40 I19 --- GaiaDR2 Gaia-DR2 ID (2)
42- 45 A4 --- SpType Spectral type using Gbp-Grp color (3)
47- 52 F6.2 pc Dist Gaia distances (4)
54- 58 F5.2 pc e_Dist Uncertainty on Gaia distances (4)
60- 63 F4.2 mag KsMAG Absolute 2MASS Ks-magnitude (5)
65- 69 F5.2 mag e_KsMAG Uncertainty on the absolute 2MASS
Ks-mag (5)
71- 74 F4.2 Msun Mass Stellar mass (5)
76- 80 F5.2 Msun e_Mass Error on stellar mass (5)
82 I1 --- binary Flag for binary systems (6)
84 I1 --- MannInd Validation flag of the stellar parameters
according to Mann (7)
86- 91 A6 --- eROSITA The eROSITA Survey where the star has
been detected
93-102 F10.6 deg RAdeg Corrected X-ray right ascension (J2000)
104-113 F10.6 deg DEdeg Corrected X-ray declination (J2000)
115-119 F5.2 arcsec SepXOpt Separation between the optical and the
X-ray positions
121-128 F8.2 10-3ct/s CRate0 Count Rate in 0.2-5.0keV
130-137 F8.2 --- DetML0 Detection Likelihood in 0.2-5.0keV
139-143 F5.2 --- HR1 Hardness ratio between the energy bands:
0.6-2.3keV and 0.2-0.6keV
145-149 F5.2 --- HR2 ?=- Hardness ratio between the energy
bands: 2.3-5.0keV and 0.6-2.3keV
151-155 F5.2 [10-7W] logLxeR eROSITA X-ray luminosity in log scale
157-161 F5.2 [10-7W] logLxR ?=- ROSAT X-ray luminosity in log scale (8)
163-167 F5.2 [-] logLx/Lbol Fractional X-ray luminosity in log scale
169-178 I10 --- TIC ?=- TIC Name
180-184 F5.2 d Prot ?=- Rotation period extracted from TESS LC
186 I1 --- f_Prot ?=- Rotation period flag (9)
188-206 F19.17 --- Ro ?=- Rossby number (10)
208-223 A16 --- SName Simbad name
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Note (1): Lepine & Gaidos (2011AJ....142..138L 2011AJ....142..138L, Cat. J/AJ/142/138) source name.
Note (2): Gaia source from Gaia Collaboration et al.
(2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345)
Note (3): Gbp-Gbp color from the table A Modern Mean Dwarf Stellar Color and
Effective Temperature Sequence, maintained by E. Mamajek
Note (4): Distance from Bailer-Jones et al. (2018AJ....156...58B 2018AJ....156...58B, Cat. I/347).
Note (5): Calculated with Mann et al. (2015PASP..127..102M 2015PASP..127..102M, 2015ApJ...804...64M 2015ApJ...804...64M)
relations.
Note (6): Flag for binary systems as follows:
0 = single star
1 = binary star
Note (7): Validation flag as follows:
0 = not valid
1 = valid
Note (8): Rate comes from the ROSAT 2RXS catalog,
Boller et al. (2016A&A...588A.103B 2016A&A...588A.103B, Cat. J/A+A/588/A103).
Note (9): Rotation period flag as follows:
0 = not reliable
1 = reliable
2 = ambiguous
Note (10): The convective turn over time is calculated using the empirical
relation from Wright et al. (2018MNRAS.479.2351W 2018MNRAS.479.2351W)
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Acknowledgements:
Enza Magaudda, magaudda(at)astro.uni-tuebingen.de
References:
The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the
SRG mission, 2022, A&A, 661, A1-A46
History:
18-May-2022: on-line version
23-Dec-2024: corrected version
(End) Patricia Vannier [CDS] 02-Dec-2021