NEW H{sub 2} COLLISION-INDUCED ABSORPTION AND NH{sub 3} OPACITY AND THE SPECTRA OF THE COOLEST BROWN DWARFS
- Los Alamos National Laboratory, P.O. Box 1663, Mail Stop F663, Los Alamos, NM 87545 (United States)
- NASA Ames Research Center, Mail Stop 245-3, Moffett Field, CA 94035 (United States)
- Physics Department, University of Texas at Austin, Austin, TX 78712 (United States)
We present new cloudy and cloudless model atmospheres for brown dwarfs using recent ab initio calculations of the line list of ammonia (NH{sub 3}) and of the collision-induced absorption of molecular hydrogen (H{sub 2}). We compare the new synthetic spectra with models based on an earlier description of the H{sub 2} and NH{sub 3} opacities. We find a significant improvement in fitting the nearly complete spectral energy distribution of the T7p dwarf Gliese 570D and in near-infrared color-magnitude diagrams of field brown dwarfs. We apply these new models to the identification of NH{sub 3} absorption in the H-band peak of very late T dwarfs and the new Y dwarfs and discuss the observed trend in the NH{sub 3}-H spectral index. The new NH{sub 3} line list also allows a detailed study of the medium-resolution spectrum of the T9/T10 dwarf UGPS J072227.51-054031.2 where we identify several specific features caused by NH{sub 3}.
- OSTI ID:
- 22034556
- Journal Information:
- Astrophysical Journal, Vol. 750, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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