Observational study of low-mass star formation in NGC 2264

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6298692

Adams, M T

The history of an actively star-forming region, containing the young, open cluster NGC 2264, is examined in this thesis using UBVRIH..cap alpha.. photographic plate material. After digitization and removal of the variable background from these plates, automatic detection and photometry algorithms yield magnitudes for a set of candidate low-mass cluster members. Using the photographic plates and a supplementary video camera H..cap alpha.. survey, these candidates are selected on the basis of their exhibiting significant H..cap alpha.. emission, large amplitude variability, or anomalously blue colors. To study the age spread in NGC 2264, a theoretical H-R diagram is constructed. Infrared photometry of 33 candidate members permits an evaluation of the bolometric luminosities of these stars; the unreddened (V-R) and (V-I) colors yield effective temperatures. The theoretical mass tracks and isochrones of Cohen and Kuhi (1979) are adopted and extrapolated to lower luminosities and temperatures. The effects of circumstellar dust and gas shells on the location of the NGC 2264 stars in the H-R diagram are examined. No systematic biases in the derived bolometric luminosities and temperatures are found. The optical and infrared excesses of these stars are found to be uncorrelated, requiring separate mechanisms for their generation. A gaseous envelope is most likely the source of the optical excess; thermal emission from hot dust most probably leads to the observed infrared excesses. An age spread for the low-mass NGC 2264 stars of greater than or equal to 10/sup 7/ years is indicated. Star formation in NGC 2264 is found to have proceeded sequentially as a function of mass and time. Low-mass star formation began approx. 2.3 x 10/sup 7/ years ago, peaked approx. 4.5 x 10/sup 6/ years ago, and declined thereafter.

• Research Organization: Arizona Univ., Tucson (USA)
• OSTI ID: 6298692
• 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
BALMER LINES
COLOR
COSMIC DUST
COSMIC GASES
DIAGRAMS
DUSTS
ELECTROMAGNETIC RADIATION
FLUIDS
GASES
GRAVITATIONAL COLLAPSE
HERTZSPRUNG-RUSSELL DIAGRAM
INFRARED RADIATION
LUMINOSITY
MASS
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
RADIATIONS
STAR CLUSTERS
TEMPERATURE MEASUREMENT
TIME DEPENDENCE