The CARMENES search for exoplanets around M dwarfs

Telluric absorption corrected high S/N optical and near-infrared template spectra of 382 M dwarf stars^★

¹ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: evangelos.nagel@hs.uni-hamburg.de
² Universität Göttingen, Institut für Astrophysik und Geophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
³ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
⁴ Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany
⁵ Department of Physics, Ariel University, Ariel 40700, Israel
⁶ Centro de Astrobiología (CSIC-INTA), ESAC, Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
⁷ ISDEFE, Beatriz de Bobadilla 3, 28040 Madrid, Spain
⁸ Institut de Ciències de l’Espai (CSIC), Campus UAB, c/ de Can Magrans s/n, 08193 Bellaterra, Barcelona, Spain
⁹ Institut d’Estudis Espacials de Catalunya (IEEC), c/ Gran Capita 2–4, 08034 Barcelona, Spain
¹⁰ Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
¹¹ Instituto de Astrofísica de Canarias, c/ Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
¹² Departamento de Astrofísica, Universidad de La Laguna, Avda. Francisco Sánchez s/n, 38206 La Laguna, Tenerife, Spain
¹³ Departamento de Física de la Tierra y Astrofísica and IPARCOS-UCM (Intituto de Física de Partículas y del Cosmos de la UCM), Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁴ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹⁵ Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
¹⁶ Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
¹⁷ Centro Astronómico Hispano en Andalucía (CSIC-Junta de Andalucía), Observatorio Astronómico de Calar Alto, Sierra de los Filabres, 04550 Gérgal, Almería, Spain

Received: 28 March 2023
Accepted: 25 September 2023

Abstract

Light from celestial objects interacts with the molecules of the Earth’s atmosphere, resulting in the production of telluric absorption lines in ground-based spectral data. Correcting for these lines, which strongly affect red and infrared wavelengths, is often needed in a wide variety of scientific applications. Here, we present the template division telluric modeling (TDTM) technique, a method for accurately removing telluric absorption lines in stars that exhibit numerous intrinsic features. Based on the Earth’s barycentric motion throughout the year, our approach is suited for disentangling telluric and stellar spectral components. By fitting a synthetic transmission model, telluric-free spectra are derived. We demonstrate the performance of the TDTM technique in correcting telluric contamination using a high-resolution optical spectral time series of the feature-rich M3.0 dwarf star Wolf 294 that was obtained with the CARMENES spectrograph. We apply the TDTM approach to the CARMENES survey sample, which consists of 382 targets encompassing 22 357 optical and 20 314 near-infrared spectra, to correct for telluric absorption. The corrected spectra are coadded to construct template spectra for each of our targets. This library of telluric-free, high signal-to-noise ratio, high-resolution (ℛ > 80 000) templates comprises the most comprehensive collection of spectral M-dwarf data available to date, both in terms of quantity and quality, and is available at the project website.