J/A+A/658/A194 Stellar parameters of 18 M dwarfs (Passegger+, 2022)
Metallicities in M dwarfs: Investigating different determination techniques.
Passegger V.M., Bello-Garcia A., Ordieres-Mere J., Antoniadis-Karnavas A.,
Marfil E., Duque-Arribas C., Amado P.J., Delgado-Mena E., Montes D.,
Rojas-Ayala B., Schweitzer A., Tabernero H.M., Bejar V.J.S., Caballero J.A.,
Hatzes A.P., Henning T., Pedraz S., Quirrenbach A., Reiners A., Ribas I.
<Astron. Astrophys. 658, A194 (2022)>
=2022A&A...658A.194P 2022A&A...658A.194P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Abundances, [Fe/H] ; Effective temperatures ;
Spectroscopy ; Optical
Keywords: methods: data analysis - techniques: spectroscopic -
stars: fundamental parameters - stars: late-type - stars: low-mass
Abstract:
Deriving metallicities for solar-like stars follows well-established
methods, but for cooler stars such as M dwarfs, the determination is
much more complicated due to forests of molecular lines that are
present. Several methods have been developed in recent years to
determine accurate stellar parameters for these cool stars
(Teff<4000K). However, significant differences can be found at times
when comparing metallicities for the same star derived using different
methods.
In this work, we determine the effective temperatures, surface
gravities, and metallicities of 18 well-studied M dwarfs observed with
the CARMENES high-resolution spectrograph following different
approaches, including synthetic spectral fitting, analysis of
pseudo-equivalent widths, and machine learning. We analyzed the
discrepancies in the derived stellar parameters, including
metallicity, in several analysis runs. Our goal is to minimize these
discrepancies and find stellar parameters that are more consistent
with the literature values.
We attempted to achieve this consistency by standardizing the most
commonly used components, such as wavelength ranges, synthetic model
spectra, continuum normalization methods, and stellar parameters. We
conclude that although such modifications work quite well for hotter
main-sequence stars, they do not improve the consistency in stellar
parameters for M dwarfs, leading to mean deviations of around 50-200K
in temperature and 0.1-0.3dex in metallicity. In particular, M dwarfs
are much more complex and a standardization of the aforementioned
components cannot be considered as a straightforward recipe for
bringing consistency to the derived parameters.
Further in-depth investigations of the employed methods would be
necessary in order to identify and correct for the discrepancies that
remain.
Description:
We present the stellar parameters for our sample of 18 M dwarfs
derived by each team during the Runs A, B, C, and C2. The columns show
Karmn identifier, method, effective temperature, surface gravity, and
metallicity [Fe/H].
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 34 18 List of studied stars
tablec1.dat 108 72 Stellar parameters from Runs A and B
tablec2.dat 108 72 Stellar parameters from Runs C and C2
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Karmn Carmencita identifier (JHHMMM+DDd)
12- 13 I2 h RAh Simbad right ascension (J2000)
15- 16 I2 min RAm Simbad right ascension (J2000)
18- 22 F5.2 s RAs Simbad right ascension (J2000)
24 A1 --- DE- Declination sign (J2000)
25- 26 I2 deg DEd Declination (J2000)
28- 29 I2 arcmin DEm Declination (J2000)
31- 34 F4.1 arcsec DEs Declination (J2000)
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Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Karmn Carmencita identifier (JHHMMM+DDd)
14- 24 A11 --- Method Method
28- 31 I4 K TeffA Effective temperature Run A
35- 37 I3 K e_TeffA Error effective temperature Run A
41- 44 F4.2 [cm/s2] loggA ?=- Surface gravity Run A
48- 51 F4.2 [cm/s2] e_loggA ?=- Error surface gravity Run A
55- 59 F5.2 [-] [Fe/H]A Metallicity Run A
63- 66 F4.2 [-] e_[Fe/H]A Error metallicity Run A
70- 73 I4 K TeffB ?=- Effective temperature Run B
77- 79 I3 K e_TeffB ?=- Error effective temperature Run B
83- 86 F4.2 [cm/s2] loggB ?=- Surface gravity Run B
90- 93 F4.2 [cm/s2] e_loggB ?=- Error surface gravity Run B
97-101 F5.2 [-] [Fe/H]B ?=- Metallicity Run B
105-108 F4.2 [-] e_[Fe/H]B ?=- Error metallicity Run B
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Byte-by-byte Description of file: tablec2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Karmn Carmencita identifier (JHHMMm+DDd)
14- 24 A11 --- Method Method (1)
28- 31 I4 K TeffC Effective temperature Run C
35- 37 I3 K e_TeffC Error effective temperature Run C
41- 44 F4.2 [cm/s2] loggC ?=- Surface gravity Run C
48- 51 F4.2 [cm/s2] e_loggC ?=- Error surface gravity Run C
55- 59 F5.2 [-] [Fe/H]C Metallicity Run C
63- 66 F4.2 [-] e_[Fe/H]C Error metallicity Run C
70- 73 I4 K TeffC2 ?=- Effective temperature Run C2
77- 79 I3 K e_TeffC2 ?=- Error effective temperature Run C2
83- 86 F4.2 [cm/s2] loggC2 ?=- Surface gravity Run C2
90- 93 F4.2 [cm/s2] e_loggC2 ?=- Error surface gravity Run C2
97-101 F5.2 [-] [Fe/H]C2 ?=- Metallicity Run C2
105-108 F4.2 [-] e_[Fe/H]C2 ?=- Error metallicity Run C2
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Note (1): Run C for ODUSSEAS corresponds to their Run C*.
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Acknowledgements:
Vera Maria Passegger, vpassegger(at)hs.uni-hamburg.de
(End) Vera Maria Passegger [HS, Germany], Patricia Vannier [CDS] 07-Dec-2021