The Near-Infrared and Optical Spectra of Methane Dwarfs and Brown Dwarfs
| dc.creator | Burrows, Adam | |
| dc.creator | Marley, M. S. | |
| dc.creator | Sharp, C. M. | |
| dc.date | 1999-08-06 | |
| dc.date | 2000-03-06 | |
| dc.date.accessioned | 2026-07-07T11:34:12Z | |
| dc.date.available | 2026-07-07T11:34:12Z | |
| dc.description | We identify the pressure--broadened red wings of the saturated potassium resonance lines at 7700 Åas the source of anomalous absorption seen in the near-infrared spectra of Gliese 229B and, by extension, of methane dwarfs in general. This conclusion is supported by the recent work of Tsuji {\it et al.} 1999, though unlike them we find that dust need not be invoked to explain the spectra of methane dwarfs shortward of 1 micron. We find that a combination of enhanced alkali abundances due to rainout and a more realistic non-Lorentzian theory of resonant line shapes may be all that is needed to properly account for these spectra from 0.5 to 1.0 microns. The WFPC2 $I$ measurement of Gliese 229B is also consistent with this theory. Furthermore, a combination of the blue wings of this K I resonance doublet, the red wings of the Na D lines at 5890 Å, and, perhaps, the Li I line at 6708 Åcan explain in a natural way the observed WFPC2 $R$ band flux of Gliese 229B. Hence, we conclude that the neutral alkali metals play a central role in the near-infrared and optical spectra of methane dwarfs and that their lines have the potential to provide crucial diagnostics of brown dwarfs. We speculate on the systematics of the near-infrared and optical spectra of methane dwarfs, for a given mass and composition, that stems from the progressive burial with decreasing \teff of the alkali metal atoms to larger pressures and depths. | |
| dc.description | Revised and accepted to Ap.J. volume 531, March 1, 2000, also available at http://jupiter.as.arizona.edu/~burrows/papers/BMS.ps | |
| dc.identifier | https://arxiv.org/abs/astro-ph/9908078 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/9908078 | |
| dc.identifier | Astrophys.J.531:438-446,2000 | |
| dc.identifier | doi:10.1086/308462 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/198163 | |
| dc.subject | Astrophysics | |
| dc.title | The Near-Infrared and Optical Spectra of Methane Dwarfs and Brown Dwarfs | |
| dc.type | text |