CARMENES input catalog of M dwarfs: VI. A time-resolved Ca II H&K catalog from archival data

Context. Radial-velocity (RV) jitter caused by stellar magnetic activity is an important factor in state-of-the-art exoplanet discovery surveys such as CARMENES. Stellar rotation, along with heterogeneities in the photosphere and chromosphere caused by activity, can result in false-positive planet detections. Hence, it is necessary to determine the stellar rotation period and compare it to any putative planetary RV signature. Long-term measurements of activity indicators such as the chromospheric emission in the Ca II H&K lines (RHK′) enable the identification of magnetic activity cycles. Aims. In order to determine stellar rotation periods and study the long-term behavior of magnetic activity of the CARMENES guaranteed time observations (GTO) sample, it is advantageous to extract RHK′ time series from archival data, since the CARMENES spectrograph does not cover the blue range of the stellar spectrum containing the Ca II H&K lines. Methods. We have assembled a catalog of 11 634 archival spectra of 186 M dwarfs acquired by seven different instruments covering the Ca II H&K regime: ESPaDOnS, FEROS, HARPS, HIRES, NARVAL, TIGRE, and UVES. The relative chromospheric flux in these lines, RHK′, was directly extracted from the spectra by rectification with PHOENIX synthetic spectra via narrow passbands around the Ca II H&K line cores. Results. The combination of archival spectra from various instruments results in time series for 186 stars from the CARMENES GTO sample. As an example of the use of the catalog, we report the tentative discovery of three previously unknown activity cycles of M dwarfs. Conclusions. We conclude that the method of extracting with the use of model spectra yields consistent results for different instruments and that the compilation of this catalog will enable the analysis of long-term activity time series for a large number of M dwarfs. © ESO 2021.We acknowledge financial support from the Agencia Estatal de Investigación of the Ministerio de Ciencia, Innovación y Universidades and the ERDF through projects PID2019-109522GB-C5[1:4]/AEI/10.13039/501100011033 and the Centre of Excellence “Severo Ochoa” and “María de Maeztu” awards to the Instituto de Astrofísica de Canarias (CEX2019-000920-S), Instituto de Astrofísica de Andalucía (SEV-2017-0709), and Centro de Astrobiología (MDM-2017-0737), and the Generalitat de Catalunya/CERCA programme. Based on observations obtained at the Canada-France-Hawai’i Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientique of France, and the University of Hawai’i. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 0100.C-0097(A), 0101.C-0516(A), 0101.D-0494(A), 0102.C-0558(A), 0102.D-0483(A), 0103.A-9009(A), 072.A-9006(A), 072.C-0488(E), 072.D-0621(A), 073.D-0038(B), 074.B-0639(A), 074.C-0364(A), 074.D-0016(A), 075.D-0614(A), 076.A-9005(A), 076.A-9013(A), 076.C-0155(A), 076.D-0560(A), 077.A-9005(A), 077.C-0364(E), 078.A-9058(A), 078.A-9059(A), 078.C-0044(A), 078.C-0333(A), 078.D-0071(D), 079.A-9007(A), 079.A-9013(B), 079.C-0255(A), 080.D-0086(C), 080.D-0086(D), 080.D-0140(A), 081.A-9005(A), 081.A-9024(A), 081.D-0190(A), 082.C-0218(A), 082.C-0718(A), 082.C-0718(B), 082.D-0953(A), 084.C-0403(A), 085.A-9027(A), 085.C-0019(A), 086.A-9014(A), 087.C-0831(A), 087.C-0991(A), 087.D-0069(A), 088.A-9032(A), 088.C-0662(B), 089.A-9007(D), 089.A-9008(A), 089.C-0440(A), 089.C-0497(A), 089.C-0732(A), 090.A-9003(A), 090.A-9010(A), 090.A-9029(A), 090.C-0200(A), 090.C-0395(A), 091.A-9004(A), 091.A-9012(A), 091.A-9032(A), 091.C-0034(A), 091.C-0216(A), 091.D-0296(A), 092.A-9009(A), 092.C-0203(A), 093.A-9001(A), 093.A-9029(A), 093.C-0343(A), 093.C-0409(A), 094.A-9029(I), 094.D-0596(A), 095.C-0551(A), 095.C-0718(A), 095.D-0685(A), 096.C-0499(A), 097.C-0561(A), 097.C-0561(B), 097.C-0624(A), 097.C-0864(B), 098.C-0518(A), 098.C-0739(A), 099.C-0205(A), 099.C-0880(A), 1102.C-0339(A), 180.C-0886(A), 183.C-0437(A), 183.C-0972(A), 191.C-0505(A), 191.C-0873(A), 191.C-0873(B), 191.C-0873(D), 191.C-0873(E), 191.C-0873(F), 192.C-0224(B), 192.C-0224(C), 192.C-0224(G), 192.C-0224(H), 192.C-0852(A), 192.C-0852(M), 198.C-0838(A), 276.C-5054(A), 60.A-9036(A), 60.A-9709(G), 69.D-0092(A), and 69.D-0478(A). This research has made use of the Keck Observatory Archive (KOA), which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration.Peer reviewe

The CARMENES search for exoplanets around M dwarfs

Context. The CARMENES instrument, installed at the 3.5 m telescope of the Calar Alto Observatory in Almería, Spain, was conceived to deliver high-accuracy radial velocity (RV) measurements with long-term stability to search for temperate rocky planets around a sample of nearby cool stars. Moreover, the broad wavelength coverage was designed to provide a range of stellar activity indicators to assess the nature of potential RV signals and to provide valuable spectral information to help characterise the stellar targets. Aims: We describe the CARMENES guaranteed time observations (GTO), spanning from 2016 to 2020, during which 19 633 spectra for a sample of 362 targets were collected. We present the CARMENES Data Release 1 (DR1), which makes public all observations obtained during the GTO of the CARMENES survey. Methods: The CARMENES survey target selection was aimed at minimising biases, and about 70% of all known M dwarfs within 10 pc and accessible from Calar Alto were included. The data were pipeline-processed, and high-level data products, including 18 642 precise RVs for 345 targets, were derived. Time series data of spectroscopic activity indicators were also obtained. Results: We discuss the characteristics of the CARMENES data, the statistical properties of the stellar sample, and the spectroscopic measurements. We show examples of the use of CARMENES data and provide a contextual view of the exoplanet population revealed by the survey, including 33 new planets, 17 re-analysed planets, and 26 confirmed planets from transiting candidate follow-up. A subsample of 238 targets was used to derive updated planet occurrence rates, yielding an overall average of 1.44 ± 0.20 planets with 1 M⊕ < Mpl sin i < 1000 M⊕ and 1 day < Porb < 1000 days per star, and indicating that nearly every M dwarf hosts at least one planet. All the DR1 raw data, pipeline-processed data, and high-level data products are publicly available online. Conclusions: CARMENES data have proven very useful for identifying and measuring planetary companions. They are also suitable for a variety of additional applications, such as the determination of stellar fundamental and atmospheric properties, the characterisation of stellar activity, and the study of exoplanet atmospheres

CARMENES input catalog of M dwarfs

Context. Radial-velocity (RV) jitter caused by stellar magnetic activity is an important factor in state-of-the-art exoplanet discovery surveys such as CARMENES. Stellar rotation, along with heterogeneities in the photosphere and chromosphere caused by activity, can result in false-positive planet detections. Hence, it is necessary to determine the stellar rotation period and compare it to any putative planetary RV signature. Long-term measurements of activity indicators such as the chromospheric emission in the Ca I