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G.J. Herczeg (JILA/University of Colorado), F. M. Walter (SUNY-Stony Brook), A. Brown (CASA/University of Colorado), J.A. Valenti (STScI), D.R. Ardila (University of California-Berkely), C.M. Johns-Krull (Rice University), G.F. Gahm (Stockholm Observatory), J.J. Lissauer (NASA/Ames Research Center), M. Simon (SUNY-Stony Brook)
We survey Lyman-band H2 fluorescence in the FUV spectrum of the CTTSs T Tau, DF Tau, RU Lupi, DG Tau and , and the wTTS V836 Tau, as observed with HST/STIS using the E140M grating and a 0\farcs2 \times 0\farcs06 aperture. The H2 is electronically excited by the broad red wing of Ly\alpha from lower levels of 1 to 2 eV, consistent with an H2 gas temperature of 2000-3000 K. This process occurs in CTTSs because the red wing of Ly\alpha is significantly enhanced by accretion onto the star. We analyze the velocity shifts, narrow widths, and fluxes of these lines, and discuss the origin of these lines in the circumstellar environment.
We also observed extended H2 from T Tau using a 52\prime\prime\times0\farcs2 slit in the G140L mode of HST/STIS. We compare the extended emission to the on-source emission, as observed with the small aperture using E140M, and discuss the physical implications for differences in these spectra.
The author(s) of this abstract have provided an email address for comments about the abstract: gregoryh@casa.colorado.edu