2000/05/29 by G. Chabrier, I. Baraffe, F. Allard +1 · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1086/309513
published as Astrophys.J.542:464-472,2000 · 38 pages, Latex file, uses aasms4.sty, accepted for publication in ApJ
arxiv created 2000/05/29 · arxiv updated 2009/12/01
We present evolutionary calculations for very-low-mass stars and brown dwarfs based on synthetic spectra and non-grey atmosphere models which include dust formation and opacity, i.e. objects with \te\simle 2800 K. The interior of the most massive brown dwarfs is shown to develop a conductive core after ∼ 2 Gyr which slows down their cooling. Comparison is made in optical and infrared color-magnitude diagrams with recent late-M and L-dwarf observations. The saturation in optical colors and the very red near-infrared colors of these objects are well explained by the onset of dust formation in the atmosphere. Comparison of the faintest presently observed L-dwarfs with these dusty evolutionary models suggests that dynamical processes such as turbulent diffusion and gravitational settling are taking place near the photosphere. As the effective temperature decreases below \te≈ 1300-1400 K, the colors of these objects move to very blue near-infrared colors, a consequence of the ongoing methane absorption in the infrared. We suggest the possibility ofa brown dwarf dearth in J,H,K color-magnitude diagrams around this temperature.