HST/COS SPECTRA OF DF Tau AND V4046 Sgr: FIRST DETECTION OF MOLECULAR HYDROGEN ABSORPTION AGAINST THE Ly{alpha} EMISSION LINE
- JILA, University of Colorado and NIST, Boulder, CO 80309-0440 (United States)
- CASA, University of Colorado, Boulder, CO 80309-0389 (United States)
We report the first detection of molecular hydrogen (H{sub 2}) absorption in the Ly{alpha} emission line profiles of two classical T Tauri stars (CTTSs), DF Tau and V4046 Sgr, observed by the Hubble Space Telescope/Cosmic Origins Spectrograph. This absorption is the energy source for many of the Lyman-band H{sub 2} fluorescent lines commonly seen in the far-ultraviolet spectra of CTTSs. We find that the absorbed energy in the H{sub 2} pumping transitions from a portion of the Ly{alpha} line significantly differ from the amount of energy in the resulting fluorescent emission. By assuming additional absorption in the H I Ly{alpha} profile along our light of sight, we can correct the H{sub 2} absorption/emission ratios so that they are close to unity. The required H I absorption for DF Tau is at a velocity close to the radial velocity of the star, consistent with H I absorption in the edge-on disk and interstellar medium. For V4046 Sgr, a nearly face-on system, the required absorption is between +100 km s{sup -1} and +290 km s{sup -1}, most likely resulting from H I gas in the accretion columns falling onto the star.
- OSTI ID:
- 21560434
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 730; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ABSORPTION
ACCRETION DISKS
BINARY STARS
ELEMENTS
EMISSION
ENERGY SOURCES
ERUPTIVE VARIABLE STARS
EVOLUTION
FLUORESCENCE
HYDROGEN
LUMINESCENCE
LYMAN LINES
NONMETALS
PHOTON EMISSION
RADIAL VELOCITY
SORPTION
STAR ACCRETION
STAR EVOLUTION
STARS
T TAURI STARS
VARIABLE STARS
VELOCITY