Towards Spectral Classification of L and T Dwarfs: Infrared and Optical Spectroscopy and Analysis
| dc.creator | Geballe, T. R. | |
| dc.creator | Knapp, G. R. | |
| dc.creator | Leggett, S. K. | |
| dc.creator | Fan, X. | |
| dc.creator | Golimowski, D. A. | |
| dc.date | 2001-08-28 | |
| dc.date | 2001-12-13 | |
| dc.date.accessioned | 2026-07-07T11:45:58Z | |
| dc.date.available | 2026-07-07T11:45:58Z | |
| dc.description | We present 0.6-2.5um, R~400 spectra of twenty-seven cool, low luminosity stars and substellar objects. Based on these and previously published spectra we develop a preliminary spectral classification system for L and T dwarfs. For late L and T types the classification system is based entirely on four spectral indices in the 1-2.5um interval. Two of these indices are derived from water absorption bands at 1.15um and 1.4um, the latter of which shows a smooth increase in depth through the L and T sequences and can be used to classify both spectral types. The other two indices make use of methane absorption features in the H and K bands, with the K band index also applicable to mid to late L dwarfs. Continuum indices shortward of 1um used by previous authors to classify L dwarfs are found to be useful only through mid L subclasses. We employ the 1.5um water index and the 2.2um methane index to complete the L classification through L9.5 and to link the new system with a modified version of the 2MASS ``Color-d'' index. By correlating the depths of the methane and water absorption features, we establish a T spectral sequence from types T0 to T8, based on all four indices, which is a smooth continuation of the L sequence. We reclassify two 2MASS L8 dwarfs as L9 and L9.5 and identify one SDSS object as L9. In the proposed system methane absorption appears in the K band approximately at L8, two subclasses earlier than its appearance in the H band. The L and T spectral classes are distinguished by the absence and presence, respectively, of H band methane absorption. | |
| dc.description | 40 pages, 14 figures, to be published in Ap.J., Jan 1, 2002 | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0108443 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0108443 | |
| dc.identifier | Astrophys.J.564:466,2002 | |
| dc.identifier | doi:10.1086/324078 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/202066 | |
| dc.subject | Astrophysics | |
| dc.title | Towards Spectral Classification of L and T Dwarfs: Infrared and Optical Spectroscopy and Analysis | |
| dc.type | text |