1. HOT GAS LINES IN T TAURI STARS
- Author
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Suzan Edwards, Hervé Abgrall, Catherine Espaillat, Lynne A. Hillenbrand, Jeff A. Valenti, Edwin A. Bergin, Laura Ingleby, Gaitee A. J. Hussain, Frederick M. Walter, David R. Ardila, Hao Yang, Thomas Bethell, Richard Alexander, Alexander Brown, Christopher M. Johns-Krull, Jeffrey L. Linsky, Gregory J. Herczeg, J. M. Brown, Evelyne Roueff, Eric Schindhelm, Scott G. Gregory, Nuria Calvet, Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], SUPA School of Physics and Astronomy [University of St Andrews], University of St Andrews [Scotland]-Scottish Universities Physics Alliance (SUPA), Center for Astrophysics and Space Astronomy [Boulder] (CASA), University of Colorado [Boulder], College of Automation Engineering, Nanjing University of Aeronautics and Astronautics (CAE-NUAA), NUAA, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Department of Space Studies [Boulder], and Southwest Research Institute [Boulder] (SwRI)
- Subjects
[PHYS]Physics [physics] ,Physics ,Photosphere ,010308 nuclear & particles physics ,FOS: Physical sciences ,Resonance ,Flux ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Redshift ,Accretion (astrophysics) ,T Tauri star ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,0103 physical sciences ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,010303 astronomy & astrophysics ,ComputingMilieux_MISCELLANEOUS ,Solar and Stellar Astrophysics (astro-ph.SR) ,Line (formation) - Abstract
For Classical T Tauri Stars (CTTSs), the resonance lines of N V, Si IV, and C IV, as well as the He II 1640 A line, act as diagnostics of the accretion process. Here we assemble a large high-resolution dataset of these lines in CTTSs and Weak T Tauri Stars (WTTSs). We present data for 35 stars: one Herbig Ae star, 28 CTTSs, and 6 WTTSs. We decompose the C IV and He II lines into broad and narrow Gaussian components (BC & NC). The most common (50 %) C IV line morphology in CTTSs is that of a low-velocity NC together with a redshifted BC. The velocity centroids of the BCs and NCs are such that V_BC > 4 * V_NC, consistent with the predictions of the accretion shock model, in at most 12 out of 22 CTTSs. We do not find evidence of the post-shock becoming buried in the stellar photosphere due to the pressure of the accretion flow. The He II CTTSs lines are generally symmetric and narrow, less redshifted than the CTTSs C IV lines, by ~10 km/sec. The flux in the BC of the He II line is small compared to that of the C IV line, consistent with models of the pre-shock column emission. The observations are consistent with the presence of multiple accretion columns with different densities or with accretion models that predict a slow-moving, low-density region in the periphery of the accretion column. For HN Tau A and RW Aur A, most of the C IV line is blueshifted suggesting that the C IV emission is produced by shocks within outflow jets. In our sample, the Herbig Ae star DX Cha is the only object for which we find a P-Cygni profile in the C IV line, which argues for the presence of a hot (10^5 K) wind. For the overall sample, the Si IV and N V line luminosities are correlated with the C IV line luminosities, although the relationship between Si IV and C IV shows large scatter about a linear relationship and suggests that TW Hya, V4046 Sgr, AA Tau, DF Tau, GM Aur, and V1190 Sco are silicon-poor., Accepted in the ApJSS. 52 pages, 9 tables, 20 figures
- Published
- 2013
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