Bolometric Temperature and Young Stars in the Taurus and Ophiuchus Complexes
Abstract
We calculated bolometric temperature (Tbol) and luminosity (Lbol) for 128 young stellar objects (YSOs) in Taurus, 74 in the Ophiuchus 'core', and 33 in the Ophiuchus 'off-core' region. We have constructed the bolometric luminosity-temperature (BLT) diagram, the log-log plot of Lbol versus Tbol, for the three samples. Tbol is defined as the temperature of a blackbody having the same frequency as the observed continuum spectrum. It measures the redness (or coldness) of an astronomical source. The BLT diagram is analogous to the H-R diagram and allows for a direct and quantitative comparison of YSOs at a wide variety of evolutionary states, ranging from the most deeply embedded stars to T Tauri stars nearly on the main sequence. We found (1) Tbol increases monotonically from embedded sources (approximately 60-500 K) to classical T Tauri stars (approximately 1000-3000 K) to weak-line T Tauri stars (approximately 2000-5000 K); (2) Tbol correlates reasonably well with the age inferred from the evolutionary models of pre-main-sequence stars and protostars for embedded 'protostars' and weak-line T Tauri stars. There is no significant correlation for the classical T Tauri stars. These results can be understood in terms of dissipation of circumstellar dust envelope and disk during the early stages of stellar evolution. Sources in the three regions have different distributions in the BLT diagram. The Ophiuchus core has the highest fraction of cold sources among the three regions. These cold sources are also more luminous than the YSOs in the other regions. The Ophiuchus off-core sample is dominated by the more evolved pre-main-sequence stars. The Taurus sources have distributions intermediate in Lbol, Tbol, and age between the Ophiuchus core and off-core distributions. These may suggest differences in the star formation history, and possibly in the stellar masses and mass accretion rates in these star-forming regions.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1995
- DOI:
- 10.1086/175703
- Bibcode:
- 1995ApJ...445..377C
- Keywords:
-
- Early Stars;
- Hertzsprung-Russell Diagram;
- Pre-Main Sequence Stars;
- Spectral Energy Distribution;
- Stellar Evolution;
- Stellar Luminosity;
- Stellar Temperature;
- Astronomical Catalogs;
- Chronology;
- Data Correlation;
- Error Analysis;
- Flux Density;
- Interstellar Extinction;
- Astrophysics;
- STARS: FUNDAMENTAL PARAMETERS;
- STARS: PRE--MAIN-SEQUENCE