RT Journal Article
T1 The CARMENES search for exoplanets around M dwarfs : the He I triplet at 10830 Å across the M dwarf sequence
A1 Fuhrmeister, B.
A1 Czesla, S.
A1 Hildebrandt, L.
A1 Montes Gutiérrez, David
A1 Diez-Alonso, E.
AB The He I infrared (IR) triplet at 10 830 Å 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 M0.0 V to M9.0 V obtained with the CARMENES high resolution optical and near-infrared spectrograph at Calar Alto to study the properties of the He I 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 M5.0 V, the He I triplet becomes undetectable in our study. This dependence on effective temperature may be related to a change in chromospheric conditions along the M dwarf 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 He I 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 (L_X∕L_bol < −5.5) in our sample or to the complex behaviour with regard to increasing depth and filling in.
PB EDP Sciences
SN 0004-6361
YR 2019
FD 2019-11-25
LK https://hdl.handle.net/20.500.14352/88361
UL https://hdl.handle.net/20.500.14352/88361
LA eng
NO Artículo firmado por 27 autores
NO German Research Foundation (DFG)
NO German Max-Planck-Gesellschaft (MPG)
NO Consejo Superior de Investigaciones Cientificas (CSIC)
NO European Union through FEDER/ERF
NO Max-Planck-Institut fur Astronomie
NO Instituto de Astrofisica de Andalucia
NO Landessternwarte Konigstuhl
NO Institut de Ciencies de l'Espai
NO Institut fur Astro-physik Gottingen
NO Universidad Complutense de Madrid
NO Thuringer Landesstern-warte Tautenburg
NO Instituto de Astrofisica de Canarias
NO Hamburger Sternwarte
NO Centro de Astrobiología
NO Centro Astronómico Hispano-Alemán
NO Ministerio de Economia y Competitividad (MINECO)
NO German Science Foundation through the Major Research Instrumentation Programme
NO Klaus Tschira Stiftung
NO State of Baden-Wurttemberg
NO Sstate of Niedersachsen
NO Junta de Andalucía
NO Centros de Excelencia Severo Ochoa
NO Unidad de Excelencia María de Maeztu
NO Generalitat de Catalunya/CERCA
DS Docta Complutense
RD 19 jun 2025