GIARPS High-resolution Observations of T Tauri stars (GHOsT)

J M Alcalá,F Vitali,S Antoniucci,T Giannini,C F Manara,A Harutyunyan,K Biazzo,A Frasca,U Munari,B Nisini,M Gangi

doi:10.1051/0004-6361/202140918

Abstract

The mass-accretion rate,Ṁacc, is a crucial parameter for the study of the evolution of accretion disks around young low-mass stellar objects (YSOs) and for planet formation studies. The Taurus star forming region (SFR) is rich in pre-main sequence stars, most of them of the T Tauri class. A variety of methodologies have been used in the past to measure mass accretion in samples of YSOs in Taurus, but despite being a general benchmark for star formation studies, a comprehensive and systematic analysis of the Taurus T Tauri population, where the stellar and accretion properties are derived homogeneously and simultaneously, is still missing. As part of the GIARPS High-resolution Observations of T Tauri stars (GHOsT) project, here we present a pilot study of the stellar and accretion properties of seven YSOs in Taurus using the spectrograph GIARPS at the Telescopio NazionaleGalileo. Contemporaneous low-resolution spectroscopic and photometric ancillary observations allow us to perform an accurate flux calibration of the high-resolution spectra. The simultaneity of the high-resolution, wide-band spectroscopic observations, from the optical to the near-infrared (NIR), the veiling measurements in such wide spectral range, and many well-calibrated emission line diagnostics allows us to derive the stellar and accretion properties of the seven YSOs in a homogeneous and self-consistent way. The procedures and methodologies presented here will be adopted in future works for the analysis of the complete GHOsT data set. We discuss the accretion properties of the seven YSOs in comparison with the 90% complete sample of YSOs in the Lupus SFR and investigate possibilities for the origin of the continuum excess emission in the NIR.

Highlights

The way in which circumstellar disks evolve and form protoplanets is deeply influenced by the processes of mass accretion onto the star, ejection of outflows, and photo-evaporation of disk material through winds (Hartmann, Herczeg & Calvet 2016; Ercolano & Pascucci 2017, and references therein)
As part of the GIARPS High-resolution Observations of T Tauri stars (GHOsT) project, here we present a pilot study of the stellar and accretion properties of seven young low-mass stellar objects (YSOs) in Taurus using the spectrograph GIARPS at the Telescopio Nazionale Galileo (TNG)
As a first step in filling this gap, here we present a pilot study of the accretion of seven YSOs in Taurus observed with TNG/GIARPS as part of the GHOsT (GIARPS High-resolution Observations of T Tauri stars) project

Summary

Introduction

The way in which circumstellar disks evolve and form protoplanets is deeply influenced by the processes of mass accretion onto the star, ejection of outflows, and photo-evaporation of disk material through winds (Hartmann, Herczeg & Calvet 2016; Ercolano & Pascucci 2017, and references therein). In order to understand planet formation it is necessary to explain how optically thick accretion disks surrounding the youngest lowmass (M 2.0M ) stars evolve into optically thin debris disks (Morbidelli & Raymond 2016) In this framework, the mass accretion rate, Macc, is a fundamental parameter for the evolution of accretion disks around young low-mass stellar objects (YSOs). The mass accretion rate can be derived from the energy released in the accretion shock (accretion luminosity Lacc; see Gullbring et al 1998; Hartmann 1998) given the stellar properties This requires measurements of excess flux in continuum and lines with respect to similar nonaccreting template stars. It is well known that Lacc, and Macc, is correlated with the line luminosity, Lline, of H i, He i, and Ca ii lines

Objectives

Results

Conclusion