Evolutionary scenarios for low-mass stars and substellar brown dwarfs

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6033010

Stringfellow, G S

Several investigations into the evolution of very low mass (VLM) stars and substellar brown dwarfs (SBDs) were conducted. The first is a numerical simulation of the evolution of optically visible protostars accreting mass from a disk. It is suggested that rotation, not deuterium burning, is simultaneously responsible for forming the disk and optically revealing the central protostar. It is assumed that the accretion energy can be radiated by either a boundary layer (BL) or the protostellar photosphere, or some combination thereof. The BL mechanism fits the observations better and indicates that T Tauri stars are accreting. Second, the evolution of isolated VLM stars and SBDs is computed for two sets of atmospheric (grain) opacities. These results are compared with other recent models and observations. The influence of a white dwarf's radiation flux on the evolution of a SBD companion is considered. Larger opacities significantly increase the radii of SBDs, but the thermal bath does not. The thermal bath increases substantially the SBD temperature and luminosity at a given age. Inclusion of both effects increases the mass range of the possible SBD companion of G29-38 significantly over previous work. As a step toward improving the equation of state for VLM stars and SBDs, internal energies obtained from Monte Carlo simulations of the One-Component Plasma are re-examined.

• Research Organization: California Univ., Santa Cruz, CA (USA)
• OSTI ID: 6033010
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPUTERIZED SIMULATION
DATA
DWARF STARS
EQUATIONS
EQUATIONS OF STATE
ERUPTIVE VARIABLE STARS
INFORMATION
LUMINOSITY
MATHEMATICAL MODELS
MONTE CARLO METHOD
NUMERICAL DATA
OPACITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PROTOSTARS
SIMULATION
STAR ACCRETION
STAR EVOLUTION
STAR MODELS
STARS
T TAURI STARS
THEORETICAL DATA
VARIABLE STARS
WHITE DWARF STARS