HADES RV programme with HARPS-N at TNG

VII. Rotation and activity of M-dwarfs from time-series high-resolution spectroscopy of chromospheric indicators^★

¹ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
e-mail: asm_ext@iac.es
² Observatoire Astronomique de l’Université de Genève, 1290 Versoix, Switzerland
e-mail: Alejandro.SuarezMascareno@unige.ch
³ Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
⁴ Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain
⁵ Institut de Ciénces de l’Espai (CSIC-IEEC), Campus UAB, Carrer de Can Magrans s/n, 08193 Cerdanyola del Vallés, Spain
⁶ INAF – Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
⁷ INAF – Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy
⁸ Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
⁹ INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
¹⁰ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
¹¹ Dipartimento di Fisica e Astronomia Galileo Galilei, Università di Padova, Vicolo dell’Osservatorio 2, 35122 Padova, Italy
¹² Fundación Galileo Galilei – INAF, Rambla José Ana Fernandez Pérez 7, 38712 Breña Baja, TF, Spain
¹³ INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
¹⁴ INAF – Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy

Received: 20 October 2017
Accepted: 5 December 2017

Abstract

We aim to investigate the presence of signatures of magnetic cycles and rotation on a sample of 71 early M-dwarfs from the HADES RV programme using high-resolution time-series spectroscopy of the Ca II H&K and Hα chromospheric activity indicators, the radial velocity series, the parameters of the cross correlation function and the V -band photometry. We used mainly HARPS-N spectra, acquired over 4 yr, and add HARPS spectra from the public ESO database and ASAS photometry light-curves as support data, extending the baseline of the observations of some stars up to 12 yr. We provide log₁₀(R′_HK) measurements for all the stars in the sample, cycle length measurements for 13 stars, rotation periods for 33 stars and we are able to measure the semi-amplitude of the radial velocity signal induced by rotation in 16 stars. We complement our work with previous results and confirm and refine the previously reported relationships between the mean level of chromospheric emission, measured by the log₁₀(R′_HK), with the rotation period, and with the measured semi-amplitude of the activity induced radial velocity signal for early M-dwarfs. We searched for a possible relation between the measured rotation periods and the lengths of the magnetic cycle, finding a weak correlation between both quantities. Using previous v sin i measurements we estimated the inclinations of the star’s poles to the line of sight for all the stars in the sample, and estimate the range of masses of the planets GJ 3998 b and c (2.5–4.9 and 6.3–12.5 M_⊕), GJ 625 b (2.82 M_⊕), GJ 3942 b (7.1–10.0 M_⊕) and GJ 15A b (3.1–3.3 M_⊕), assuming their orbits are coplanar with the stellar rotation.