A FAR-ULTRAVIOLET ATLAS OF LOW-RESOLUTION HUBBLE SPACE TELESCOPE SPECTRA OF T TAURI STARS
- JILA, University of Colorado and NIST, Boulder, CO 80309-0440 (United States)
- Max-Planck-Institut fuer extraterrestriche Physik, 85741 Garching (Germany)
- CASA, University of Colorado, Boulder, CO 80309-0389 (United States)
- Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States)
- Department of Astronomy, University of Michigan, 830 Dennison Building, Ann Arbor, MI 48109 (United States)
We present a far-ultraviolet (FUV) spectral atlas consisting of spectra of 91 pre-main-sequence stars. Most stars in this sample were observed with the Space Telescope Imaging Spectrograph and Advanced Camera for Surveys on the Hubble Space Telescope (HST). A few archival spectra from the International Ultraviolet Explorer and the Goddard High Resolution Spectrograph on HST are included for completeness. We find strong correlations among the O I {lambda}1304 triplet, the Si IV {lambda}{lambda}1394/1403 doublet, the C IV {lambda}1549 doublet, and the He II {lambda}1640 line luminosities. For classical T Tauri stars (CTTSs), we also find strong correlations between these lines and the accretion luminosity, suggesting that these lines form in processes related to accretion. These FUV line fluxes and X-ray luminosity correlate loosely with large scatters. The FUV emission also correlates well with H{alpha}, H{beta}, and Ca II K line luminosities. These correlations between FUV and optical diagnostics can be used to obtain rough estimates of FUV line fluxes from optical observations. Molecular hydrogen (H{sub 2}) emission is generally present in the spectra of actively accreting CTTSs but not the weak-lined T Tauri stars that are not accreting. The presence of H{sub 2} emission in the spectrum of HD 98800 N suggests that the disk should be classified as actively accreting rather than a debris disk. We discuss the importance of FUV radiation, including the hydrogen Ly{alpha} line, on the photoevaporation of exoplanet atmospheres. We find that the Ca II/C IV flux ratios for more evolved stars are lower than those for less evolved accretors, indicating preferential depletion of refractory metals into dust grains.
- OSTI ID:
- 22004264
- Journal Information:
- Astrophysical Journal, Vol. 744, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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