THE ATMOSPHERES OF T-TAURI STARS .2. CHROMOSPHERIC LINE FLUXES AND VEILING

被引:30
作者
BATALHA, CC
BASRI, G
机构
[1] UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA
[2] CNPQ, OBSERV NACL, DEPT ASTROFIS, RIO DE JANEIRO, BRAZIL
关键词
LINE; FORMATION; RADIATIVE TRANSFER; STARS; CHROMOSPHERES; PRE-MAIN-SEQUENCE;
D O I
10.1086/172926
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
A set of high-resolution calibrated spectra of southern T Tauri Stars (TTS), comprising objects with Halpha equivalent widths ranging from 3 to 40 angstrom are used to derive one-component plane-parallel chromospheric models. Our motivation is to discover how much emission activity can truly be ascribed to stellar activity, using real calibrated stellar data. We find that simple models can reproduce the Ca II line at 8542 angstrom for most of the stars. The chromospheric enhancements are comparable to the ones found among active main-sequence stars of similar spectral type. These models cannot account for the veiling observed in TTS. Likewise, realistic TTS chromospheres are unable to create the observed Balmer jumps. The targets have a range of Halpha strength that allow us to study possible correlations among narrow symmetric emission lines, and Halpha which probes nonstellar regions. On the basis of their stellar versus systemic luminosities, Sz 77, Sz 82, and Sz 19 present signatures of disk accretion, in addition to the previously reported case of Sz 98. By correlating the fluxes of the Ca II IR line, Halpha and the near-infrared excess we conclude that disk accretion may enhance the luminosity of typical chromospheric emission lines.
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页码:363 / 374
页数:12
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