Astronomy and Astrophysics, volume 606A, 48-48 (2017/10-1)
High-resolution TNG spectra of T Tauri stars. Near-IR GIANO observations of the young variables XZ Tauri and DR Tauri.
ANTONIUCCI S., NISINI B., BIAZZO K., GIANNINI T., LORENZETTI D., SANNA N., HARUTYUNYAN A., ORIGLIA L. and OLIVA E.
Abstract (from CDS):
Aims. We aim to characterise the star-disk interaction region in T Tauri stars that show photometric and spectroscopic variability.
Methods. We used the GIANO instrument at the Telescopio Nazionale Galileo to obtain near-infrared high-resolution spectra (R∼50000) of XZ Tau and DR Tau, which are two actively accreting T Tauri stars classified as EXors. Equivalent widths and profiles of the observed features are used to derive information on the properties of the inner disk, the accretion columns, and the winds.
Results. Both sources display composite HI line profiles, where contributions from both accreting gas and high-velocity winds can be recognised. These lines are progressively more symmetric and narrower with increasing upper energy which may be interpreted in terms of two components with different decrements or imputed to self-absorption effects. XZ Tau is observed in a relatively high state of activity with respect to literature observations. The variation of the HeI 1.08µm line blue-shifted absorption, in particular, suggests that the inner wind has undergone a dramatic change in its velocity structure, connected with a recent accretion event. DR Tau has a more stable wind as its HeI 1.08µm absorption does not show variations with time in spite of strong variability of the emission component. TheIR veiling in the two sources can be interpreted as due to blackbody emission at temperatures of 1600K and 2300K for XZ Tau and DR Tau, respectively, with emitting areas ∼30 times larger than the central star. While for XZ Tau these conditions are consistent with emission from the inner rim of the dusty disk, the fairly high temperature inferred for DR Tau might suggest that its veiling originates from a thick gaseous disk located within the dust sublimation radius. Strong and broad metallic lines, mainly from CI and FeI, are detected in XZ Tau, similar to those observed in other EXor sources during burst phases. At variance, DR Tau shows weaker and narrower metallic lines, despite its larger accretion luminosity. This suggests that accretion is not the only driver of metallic line excitation.
Conclusions. The presented observations demonstrate the potential of wide-band, high-resolution near-IR spectroscopy to simultaneously probe the different phenomena that occur in the interaction region between the stellar magnetosphere and the accretion disk, thus providing hints on how these two structures are linked to each other.
© ESO, 2017
stars: variables: T Tauri, Herbig Ae/Be - stars: pre-main sequence - line: profiles - stars: individual: XZ Tau - stars: individual: DR Tau - techniques: spectroscopic - techniques: spectroscopic
View the reference in ADS
To bookmark this query, right click on this link: simbad:2017A&A...606A..48A and select 'bookmark this link' or equivalent in the popup menu