Statistical classes of cluster stars are used to identify the observed early-type pre-main-sequence stars of the Orion Nebula cluster. The Orion Nebula cluster zero-age-main-sequence is identified in the color-magnitude diagrams. For this determination, the cluster standard stars are used which have normal energy distributions and precise spectral types. The cluster OB and AO nonstandard stars is studied. The presence of grain size distributions containing anomalously large grains is proposed to explain both the dark cloud extinction type and the ultraviolet extinction anomaly. The presence of spatially resolvable circumstellar regions with a disk-like shape or containing optically thick condensations is suggested by the excess infrared energy distributions of several stars. An alternate explanation of the cluster evolution state is presented whereby the majority of the observed A-type stars are field stars. Three pre-main-sequence candidates (BR 405, 767, and 884) are identified, all of which have relatively large excess infrared luminosities.
- Pub Date:
- Physics: Astronomy and Astrophysics;
- Main Sequence Stars;
- Statistical Analysis;
- Particle Size Distribution;