Please use this identifier to cite or link to this item:
|Title:||X-shooter spectroscopy of young stellar objects. V. Slow winds in T Tauri stars||Authors:||Natta, A.
ALCALA', JUAN MANUEL
|Issue Date:||2014||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||569||First Page:||A5||Abstract:||Disks around T Tauri stars are known to lose mass, as best shown by the profiles of the forbidden emission lines of low-ionization species. At least two separate kinematic components have been identified, one characterized by velocity shifts of tens to hundreds of km s<SUP>-1</SUP> (HVC) and one with a much lower velocity of a few km s<SUP>-1</SUP> (LVC). The HVC are convincingly associated to the emission of jets, but the origin of the LVC is still unknown. In this paper we analyze the forbidden line spectrum of a sample of 44 mostly low-mass young stars in Lupus and σ Ori observed with the X-shooter ESO spectrometer. We detect forbidden line emission of O i, O ii, S ii, N i, and N ii, and characterize the line profiles as LVC, blueshifted HVC, and redshifted HVC. We focus our study on the LVC. We show that there is a good correlation between line luminosity and both L<SUB>star</SUB> and the accretion luminosity (or the mass accretion rate) over a large interval of values (L<SUB>star</SUB>~ 10<SUP>-2</SUP>-1 L<SUB>☉</SUB>; L<SUB>acc</SUB>~ 10<SUP>-5</SUP>-10<SUP>-1</SUP> L<SUB>☉</SUB>; Ṁ<SUB>acc</SUB>~ 10<SUP>-11</SUP> - 10<SUP>-7</SUP> M<SUB>☉</SUB>/yr). The lines show the presence of a slow wind (V<SUB>peak</SUB>< 20 km s<SUP>-1</SUP>) that is dense (n<SUB>H</SUB>> 10<SUP>8</SUP> cm<SUP>-3</SUP>), warm (T ~ 5000-10 000 K), mostly neutral. We estimate the mass of the emitting gas and provide a value for the maximum volume it occupies. Both quantities increase steeply with the stellar mass, from ~ 10<SUP>-12</SUP> M<SUB>☉</SUB> and ~0.01 AU<SUP>3</SUP> for M<SUB>star</SUB>~ 0.1 M<SUB>☉</SUB>, to ~ 3 × 10<SUP>-10</SUP> M<SUB>☉</SUB> and ~1 AU<SUP>3</SUP> for M<SUB>star</SUB>~ 1 M<SUB>☉</SUB>, respectively. These results provide quite stringent constraints to wind models in low-mass young stars, that need to be explored further. Based on observations collected at the European Souther Observatory at Paranal, under programs 084.C-0269(A), 085.C-0238(A), 086.C-0173(A), 087.C-0244(A) and 089.C-0143(A).Appendices are available in electronic form at <A href="http://www.aanda.org/10.1051/0004-6361/201424136/olm">http://www.aanda.org</A>||Description:||We are indebted to Bruce Draine for computing the line emissivities used in this work and to Francesca Bacciotti, Barbara Ercolano, Ilaria Pascucci, and Malcolm Walmsley for useful discussions. We thank V. D’Odorico, P. Goldoni and A. Modigliani for their help with the X-shooter pipeline, and F. Getman and G. Capasso for the installation of the different pipeline versions at Capodimonte. Financial support from INAF, under PRIN2013 programe “Disks, jets and the dawn of planets” is also acknowledged.||URI:||http://hdl.handle.net/20.500.12386/12224||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201424136||Bibcode ADS:||2014A&A...569A...5N|
|Appears in Collections:||1.01 Articoli in rivista|
Show full item record
Items in DSpace are published in Open Access, unless otherwise indicated.