Near-infrared spectroscopy of young stellar objects. Ph. D. Thesis
Near-infrared spectroscopic observations of young stellar objects are presented. Spectra were obtained of the first overtone bands of CO, the hydrogen Br gamma line, and the S(1)v=1-0 line of H2. The majority of objects observed have luminosities less than 1000 solar luminosity. The CO overtone bands were found in emission in 6 out of 31 objects. Two models are discussed for producing the CO emission. In the first, models are calculated for steady state accretion disks. The radial distribution of temperature in the disk was calculated by balancing the heating and cooling in the disk. The resulting model disks have optically thin regions with sufficient temperatures and densities for vibrational excitation of CO. The models also reproduce the observed increase in CO luminosity with increasing stellar luminosity. The second model considered is a spherical, stellar wind with velocities of 100 to 300 km/s. The CO emission from the wind is computed as a function of mass loss rate. Thirty objects were measured for Br gamma emission. Four new detections of H2 emission in young stars are also reported. It was also verified that the proportionality between hydrogen recombination line strength and stellar luminosity extends down to 1 solar luminosity objects. The relation of recombination line emission to radio continuum emission, the momentum in the ionized wind, and the relationship of the ionized gas to large scale molecular outflows are discussed.
- Research Organization:
- Texas Univ., Austin, TX (USA)
- OSTI ID:
- 5509649
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
Similar Records
Measurements of Br-gamma and H2 in young stellar objects
Inner Warm Disk of ESO Hα 279a Revealed by NA i and CO Overtone Emission Lines
Related Subjects
GENERAL PHYSICS
STAR EVOLUTION
STAR MODELS
STARS
INFRARED SPECTRA
ACCRETION DISKS
CARBON MONOXIDE
EXPERIMENTAL DATA
LUMINOSITY
MATHEMATICAL MODELS
STELLAR WINDS
TEMPERATURE DISTRIBUTION
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DATA
INFORMATION
NUMERICAL DATA
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECTRA
STELLAR ACTIVITY
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources