J/A+A/654/A118 Vanadium measurements for 135 M dwarfs (Shan+, 2021)
The CARMENES search for exoplanets around M dwarfs:
Not-so-fine hyperfine-split vanadium lines in cool star spectra.
Shan Y., Reiners A., Fabbian D., Marfil E., Montes D., Tabernero H.M.,
Ribas I., Caballero J.A., Quirrenbach A., Amado P.J., Aceituno J.,
Bejar V.J.S., Cortes-Contreras M., Dreizler S., Hatzes A.P., Henning T.,
Jeffers S.V., Kaminski A., Kuerster M., Lafarga M., Morales J.C., Nagel E.,
Palle E., Passegger V.M., Rodriguez-Lopez C., Schweitzer A., Zechmeister M.
<Astron. Astrophys. 654, A118 (2021)>
=2021A&A...654A.118S 2021A&A...654A.118S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Abundances ; Atomic physics ; Line Profiles ;
Spectroscopy ; Optical
Keywords: atomic data - line: profiles - techniques: spectroscopic -
stars: abundances - stars: low-mass
Abstract:
M-dwarf spectra are complex and notoriously difficult to model, posing
challenges to understanding their photospheric properties and
compositions in depth. Vanadium (V) is an iron-group element whose
abundance supposedly closely tracks that of iron, but has origins that
are not completely understood.
Our aim is to characterize a series of neutral vanadium atomic
absorption lines in the 800-910nm wavelength region of high
signal-to-noise, high-resolution, telluric-corrected M-dwarf spectra
from the CARMENES survey. Many of these lines are prominent and
exhibit a distinctive broad and flat-bottom shape -- a result of
hyperfine splitting (HFS). We investigate the potential and
implications of these HFS-split lines for abundance analysis of cool
stars.
With standard spectral synthesis routines, as provided by the
spectroscopy software iSpec and the latest atomic data (including HFS)
available from the VALD3 database, we model these striking line
profiles. We use them to measure V abundances of cool dwarfs.
We determine V abundances for 135 early-M dwarfs (M0.0V to M3.5V) in
the CARMENES guaranteed time observations sample. They exhibit a
[V/Fe]-[Fe/H] trend consistent with that derived from nearby FG
dwarfs. The tight (±0.1dex) correlation between [V/H] and [Fe/H]
suggests the potential application of V as an alternative metallicity
indicator in M dwarfs. We also show hints that a neglect to model HFS
could partially explain the temperature correlation in V abundance
measurements observed in previous studies of samples involving dwarf
stars with Teff≤5300K.
Our work suggests that HFS can impact certain absorption lines in cool
photospheres more severely than in Sun-like ones. Therefore, we
advocate that HFS should be carefully treated in abundance studies in
stars cooler than ∼5000 K. On the other hand, strong HFS split lines
in high-resolution spectra present an opportunity for precision
chemical analyses of large samples of cool stars. The V-to-Fe trends
exhibited by the local M dwarfs continue to challenge theoretical
models of V production in the Galaxy.
Description:
Table A1 presents the measured V abundances ([V/H]) for 135 nearby
early-M dwarfs from the CARMENES GTO sample. Two sets of measurements
are given, which are based on two independently measured sets of
fundamental stellar parameters for this sample (Schweitzer et al.,
2019A&A...625A..68S 2019A&A...625A..68S, Cat. J/A+A/625/A68 and Marfil et al., submitted).
Rotational velocities from Reiners et al. (2018A&A...612A..49R 2018A&A...612A..49R, Cat.
J/A+A/612/A49) and disk kinematic membership designations
(Cortes-Contreras+ in prep) are also included.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 80 135 Vanadium abundances for 135 M dwarfs
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See also:
J/A+A/625/A68 : Radii and masses of the CARMENES targets (Schweitzer+, 2019)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Karmn CARMENES identifier (JHHMMm+DDdA)
13- 17 A5 --- SpType Luminosity class V spectral type (1)
19- 21 F3.1 km/s vsini Projected rotational velocity (2)
23- 26 I4 K Teffs Effective temperature, from Schweitzer et al.
(2019A&A...625A..68S 2019A&A...625A..68S, Cat. J/A+A/625/A68)
28- 31 F4.2 [cm/s2] loggs Surface gravity, from Schweitzer et al.
(2019A&A...625A..68S 2019A&A...625A..68S, Cat. J/A+A/625/A68)
33- 37 F5.2 [-] [Fe/H]s Metallicity, from Schweitzer et al.
(2019A&A...625A..68S 2019A&A...625A..68S, Cat. J/A+A/625/A68)
39- 43 F5.2 [-] [V/H]s Vanadium abundance based on, from Schweitzer
et al. (2019A&A...625A..68S 2019A&A...625A..68S,
Cat. J/A+A/625/A68)
45- 48 F4.2 [-] e_[V/H]s Error of vanadium abundance based on, from
Schweitzer et al. (2019A&A...625A..68S 2019A&A...625A..68S,
Cat. J/A+A/625/A68)
50- 53 I4 K Teffm Effective temperature, from
Marfil et al. (submitted)
55- 58 F4.2 [cm/s2] loggm Surface gravity, from
Marfil et al. (submitted)
60- 64 F5.2 [-] [Fe/H]m Metallicity, from Marfil et al. (submitted)
66- 70 F5.2 [-] [V/H]m Vanadium abundance based on, from
Marfil et al. (submitted)
72- 75 F4.2 [-] e_[V/H]m Error of vanadium abundance based on,
from Marfil et al. (submitted)
77- 80 A4 --- Disk Kinematic disk membership (3)
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Note (1): Spectral types are from Alonso-Floriano et al.
(2015A&A...577A.128A 2015A&A...577A.128A, Cat. J/A+A/577/A128)
Note (2): Projected rotational velocities (vsini) are as given in Reiners et al.
(2018A&A...612A..49R 2018A&A...612A..49R, cat. J/A+A/612/A49)
Note (3): Kinematic disk membership assignments from Cortes-Contreras et al.
(in prep.) as follows:
TD = thick disc
TD-D = thick disc-thin disc transition
D = thin disc
YD = young disc
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Acknowledgements:
Yutong Shan, yutong.shan(at)uni-goettingen.de
(End) Patricia Vannier [CDS] 18-Aug-2021