The CARMENES search for exoplanets around M dwarfs

Measuring precise radial velocities in the near infrared: The example of the super-Earth CD Cet b^★,★★

¹ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
e-mail: fbauer@iaa.es
² Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
e-mail: zechmeister@astro.physik.uni-goettingen.de
³ Landessternwarte, Zentrum für Astronomie der Universtät Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany
⁴ Centro de Astrobiología (CSIC-INTA), ESAC, camino bajo del castillo s/n, 28049 Villanueva de la Cañada, Madrid, Spain
⁵ Centro Astronómico Hispano-Alemán (CSIC-Junta de Andalucía), Observatorio Astronómico de Calar Alto, Sierra de los Filabres, 04550 Gérgal, Almería, Spain
⁶ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁷ Institut de Ciéncies de l’Espai (ICE, CSIC), Campus UAB, c/de Can Magrans s/n, 08193 Bellaterra, Barcelona, Spain
⁸ Institut d’Estudis Espacials de Catalunya (IEEC), C/Gran Capità 2-4, 08034 Barcelona, Spain
⁹ Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
¹⁰ Departamento de Astrofísica, Universidad de La Laguna, 38026 La Laguna, Tenerife, Spain
¹¹ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
¹² 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
¹³ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany

Received: 26 March 2020
Accepted: 26 May 2020

Abstract

The high-resolution, dual channel, visible and near-infrared spectrograph CARMENES offers exciting opportunities for stellar and exoplanetary research on M dwarfs. In this work we address the challenge of reaching the highest radial velocity precision possible with a complex, actively cooled, cryogenic instrument, such as the near-infrared channel. We describe the performance of the instrument and the work flow used to derive precise Doppler measurements from the spectra. The capability of both CARMENES channels to detect small exoplanets is demonstrated with the example of the nearby M5.0 V star CD Cet (GJ 1057), around which we announce a super-Earth (4.0 ± 0.4 M_⊕) companion on a 2.29 d orbit.