Issue |
A&A
Volume 678, October 2023
|
|
---|---|---|
Article Number | A1 | |
Number of page(s) | 20 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361/202347161 | |
Published online | 27 September 2023 |
The CARMENES search for exoplanets around M dwarfs
Behaviour of the Paschen lines during flares and quiescence★
1
Hamburger Sternwarte, Universität Hamburg,
Gojenbergsweg 112,
21029
Hamburg, Germany
e-mail: bfuhrmeister@hs.uni-hamburg.de
2
Thüringer Landessternwarte Tautenburg,
Sternwarte 5,
07778
Tautenburg, Germany
3
Centro de Astrobiología, CSIC-INTA,
Camino Bajo del Castillo s/n,
28692
Villanueva de la Cañada, Madrid, Spain
4
Max-Planck-Institut für Sonnensystemforschung,
Justus-von-Liebig-Weg 3,
37077
Göttingen, Gemany
5
Institut für Astrophysik,
Friedrich-Hund-Platz 1,
37077
Göttingen, Germany
6
Facultad de Ciencias Físicas, Departamento de Física de la Tierra y Astrofísica; IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Universidad Complutense de Madrid,
28040
Madrid, Spain
7
Institut d’Estudis Espacials de Catalunya,
08034
Barcelona, Spain
8
Institut de Ciències de l’Espai (CSIC),
Campus UAB, c/ de Can Magrans s/n,
08193
Bellaterra, Barcelona, Spain
9
Landessternwarte, Zentrum für Astronomie der Universität Heidelberg,
Königstuhl 12,
69117
Heidelberg, Germany
10
Instituto de Astrofísica de Andalucía (CSIC),
Glorieta de la Astronomía s/n,
18008
Granada, Spain
11
Max-Planck-Institut für Astronomie,
Königstuhl 17,
69117
Heidelberg, Germany
12
Instituto de Astrofísica de Canarias,
c/ Vía Láctea s/n,
38205
La Laguna, Tenerife, Spain
13
Departamento de Astrofísica, Universidad de La Laguna (ULL),
38206
La Laguna, Tenerife, Spain
14
Centro Astronómico Hispano en Andalucía, Observatorio Astronómico de Calar Alto,
Sierra de los Filabres,
04550
Gérgal, Almería, Spain
Received:
12
June
2023
Accepted:
7
August
2023
The hydrogen Paschen lines are known activity indicators, but studies of them in M dwarfs during quiescence are as rare as their reports in flare studies. This situation is mostly caused by a lack of observations, owing to their location in the near-infrared regime, which is covered by few high-resolution spectrographs. We study the Paβ line, using a sample of 360 M dwarfs observed by the CARMENES spectrograph. Descending the spectral sequence of inactive M stars in quiescence, we find the Paβ line to get shallower until about spectral type M3.5 V, after which a slight re-deepening is observed. Looking at the whole sample, for stars with Hα in absorption, we find a loose anti-correlation between the (median) pseudo-equivalent widths (pEWs) of Hα and Paβ for stars of similar effective temperature. Looking instead at time series of individual stars, we often find correlation between pEW(Hα) and pEW(Paβ) for stars with Hα in emission and an anti-correlation for stars with Hα in absorption. Regarding flaring activity, we report the automatic detection of 35 Paschen line flares in 20 stars. Additionally we found visually six faint Paschen line flares in these stars plus 16 faint Paschen line flares in another 12 stars. In strong flares, Paschen lines can be observed up to Pa 14. Moreover, we find that Paschen line emission is almost always coupled to symmetric Hα line broadening, which we ascribe to Stark broadening, indicating high pressure in the chromosphere. Finally we report a few Paβ line asymmetries for flares that also exhibit strong Hα line asymmetries.
Key words: stars: activity / stars: chromospheres / stars: late-type
Full Table 2 is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/678/A1
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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