Published 2023 | Version v1
Journal article

Gaia Data Release 3. Stellar chromospheric activity and mass accretion from Ca II IRT observed by the Radial Velocity Spectrometer

Others:
INAF - Osservatorio Astrofisico di Catania (OACT) ; Istituto Nazionale di Astrofisica (INAF)
Royal Observatory of Belgium [Brussels] (ROB)
INAF - Osservatorio Astronomico di Padova (OAPD) ; Istituto Nazionale di Astrofisica (INAF)
Joseph Louis LAGRANGE (LAGRANGE) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
INAF - Osservatorio Astronomico di Capodimonte (OAC) ; Istituto Nazionale di Astrofisica (INAF)
Department of Astronomy and Space Physics [Uppsala] ; Uppsala University
Universidade da Coruña
Max Planck Institute for Astronomy (MPIA)
National Observatory of Athens (NOA)
FEMIS 2021 ; Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB) ; Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)) ; Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Institut de Physique de Rennes (IPR) ; Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)
Centre National d'Études Spatiales [Toulouse] (CNES)
Thales Services ; THALES [France]
Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB) ; Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Institut d'Astrophysique de Paris (IAP) ; Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Description

Context: The Gaia Radial Velocity Spectrometer provides the unique opportunity of a spectroscopic analysis of millions of stars at medium-resolution in the near-infrared. This wavelength range includes the Ca II infrared triplet (IRT), which is a good diagnostics of magnetic activity in the chromosphere of late-type stars.Aims: Here we present the method devised for inferring the Gaia stellar activity index together with its scientific validation.Methods: A sample of well studied PMS stars is considered to identify the regime in which the Gaia stellar activity index may be affected by mass accretion. The position of these stars in the colour-magnitude diagram and the correlation with the amplitude of the photometric rotational modulation is also scrutinised.Results. Gaia DR3 contains a stellar activity index derived from the Ca ii IRT for some 2 × 106nstars in the Galaxy. This represents a gold mine for studies on stellar magnetic activity and mass accretion in the solar vicinity. Three regimes of the chromospheric stellar activity are identified, confirming suggestions made by previous authors on much smaller R'HK datasets. The highest stellar activity regime is associated with PMS stars and RS CVn systems, in which activity is enhanced by tidal interaction. Some evidence of a bimodal distribution in MS stars with Teff ⩾ 5000 Kis also found, which defines the two other regimes, without a clear gap in between. Stars with 3500 K ≤ Teff ≤ 5000 K are found to be either very active PMS stars or active MS stars with a unimodal distribution in chromospheric activity. A dramatic change in the activity distribution is found for Teff ≤ 3500 K, with a dominance of low activity stars close to the transition between partially- and fully-convective stars and a rise in activitydown into the fully-convective regime.

Abstract

18 pages, 10 figures, 2 tables, submitted to A&A

Additional details

Created:
April 22, 2023
Modified:
November 29, 2023