A new probe of the planet-forming region in T Tauri disks

被引:99
作者
Bergin, E
Calvet, N
Sitko, ML
Abgrall, H
D'Alessio, P
Herczeg, GJ
Roueff, E
Qi, CH
Lynch, DK
Russell, RW
Brafford, SM
Perry, RB
机构
[1] Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA
[2] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
[3] Univ Cincinnati, Dept Phys, Cincinnati, OH 45221 USA
[4] Observ Paris, CNRS, Lab Universe & Theories, UMR 8102,Sect Meudon, F-92195 Meudon, France
[5] Univ Nacl Autonoma Mexico, Inst Astron, Morelia 58089, Michoacan, Mexico
[6] Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA
[7] Aerosp Corp, Los Angeles, CA 90009 USA
[8] Univ Dayton, Sch Law, Dayton, OH 45469 USA
[9] NASA, Langley Res Ctr, Hampton, VA 23681 USA
基金
美国国家航空航天局;
关键词
accretion; accretion disks; astrobiology; astrochemistry; circumstellar matter; stars : pre-main-sequence; ultraviolet : stars;
D O I
10.1086/425865
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present new observations of the far-ultraviolet (FUV; 1100-2200 Angstrom) radiation field and the near- to mid-A IR (3-13.5 mum) spectral energy distribution (SED) of a sample of T Tauri stars selected on the basis of bright molecular disks (GM Aur, DM Tau, and LkCa 15). In each source we find evidence for Lyalpha-induced H(2) fluorescence and an additional source of FUV continuum emission below 1700 Angstrom. Comparison of the FUV spectra to a model of H(2) excitation suggests that the strong continuum emission is due to electron impact excitation of H(2). The ultimate source of this excitation is likely X-ray irradiation that creates hot photoelectrons mixed in the molecular layer. Analysis of the SED of each object finds the presence of inner disk gaps with sizes of a few AU in each of these young (similar to1 Myr) stellar systems. We propose that the presence of strong H(2) continuum emission and inner disk clearing are related by the increased penetration power of high-energy photons in gas-rich regions with low grain opacity.
引用
收藏
页码:L133 / L136
页数:4
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