J/A+A/632/A24 HeI IR triplet measurements for M dwarfs (Fuhrmeister+, 2019)
The CARMENES search for exoplanets around M dwarfs.
The He I triplet at 10830Å across the M dwarf sequence.
Fuhrmeister B., Czesla S., Hildebrandt L., Nagel E., Schmitt J.H.M.M.,
Hintz D., Johnson E.N., Sanz-Forcada J., Schoefer P., Jeffers S.V.,
Caballero J.A., Zechmeister M., Reiners A., Ribas I., Amado P.J.,
Quirrenbach A., Bauer F.F., Bejar V.J.S., Cortes-Contreras M.,
Diez-Alonso E., Dreizler S., Galadi-Enriquez D., Guenther E.W.,
Kaminski A., Kuerster M., Lafarga M., Montes D.
<Astron. Astrophys. 632, A24 (2019)>
=2019A&A...632A..24F 2019A&A...632A..24F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Spectra, infrared
Keywords: stars: activity - stars: chromospheres - stars: late-type
Abstract:
The HeI infrared (IR) triplet at 10830Å is an important activity
indicator for the Sun and in solar-type stars, however, it has rarely
been studied in relation to M dwarfs to date. In this study, we use
the time-averaged spectra of 319 single stars with spectral types
ranging from M0.0V to M9.0V obtained with the CARMENES high resolution
optical and near-infrared spectrograph at Calar Alto to study the
properties of the HeI IR triplet lines. In quiescence, we find the
triplet in absorption with a decrease of the measured pseudo
equivalent width (pEW) towards later sub-types. For stars later than
M5.0V, the HeI triplet becomes undetectable in our study. This
dependence on effective temperature may be related to a change in
chromospheric conditions along theMdwarf sequence. When an emission in
the triplet is observed, we attribute it to flaring. The absence of
emission during quiescence is consistent with line formation by
photo-ionisation and recombination, while flare emission may be caused
by collisions within dense material. The HeI triplet tends to increase
in depth according to increasing activity levels, ultimately becoming
filled in; however, we do not find a correlation between the pEW(He
IR) and X-ray properties. This behaviour may be attributed to the
absence of very inactive stars (LX/Lbol←5.5) in our sample or to
the complex behaviour with regard to increasing depth and filling in.
Description:
We measure the pseudo-equivalent width (pEW) in the averaged stellar
spectra using a Voigt fit with four Voigt components to account for
neighbouring lines. The fit does not account for the bluest HeI
triplet component and treats the two redder components as one
component as they are totally blended for the used resolution of
80400. For comparison purposes we give also pEW values of Hα,
the bluest CaII IR triplet line, and the HeI D3 line which were
obtained by integration over the line from the same spectra. As a
further comparison for the activity level of the star we give
LX/Lbol values mostly taken from the ROSAT all-sky survey.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 96 164 HeI infrared triplet pseudo equivalent width
(pEW) measurements
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Karmn CARMENES identification
14- 33 A20 --- Name Common name of the star
35- 38 A4 --- SpType Spectral type of the star
41- 44 I4 K Teff Effective temperature
47- 52 F6.3 0.1nm pEW(HeIR) He IR pseudo equivalent width
54- 58 F5.3 0.1nm e_pEW(HeIR) Error of pEW(HeIR)
61- 65 F5.3 --- chi2 chi2 of the Voigt fit to He IR line
68- 73 F6.3 0.1nm pEW(Halpha) Hα pseudo equivalent width
75- 80 F6.3 0.1nm pEW(CaIRT) Bluest component of CaII IRT
pseudo equivalent width
83- 88 F6.3 0.1nm pEW(HeD3) He D3 pseudo equivalent width
91- 96 F6.3 --- LX/Lbol ? X-ray to bolometric luminosity ratio
taken mostly from RASS
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Acknowledgements:
Birgit Fuhrmeister, bfuhrmeister(at)hs.uni-hamburg.de
(End) B. Fuhrmeister [Hamburg Univ., Germany], P. Vannier [CDS] 31-Oct-2019