NRAO/Socorro Colloquium Series:
4 October 1996
Lynne Hillenbrand
Univ. of California, Berkeley
The Stellar Population, Star-Forming History,
and Structure of the Orion Nebula Cluster
We study the stellar population of the Orion Nebula Cluster (ONC) based on
a synthesis of optical spectroscopy, optical photometry, and infrared photometry
for a total sample numbering ~1600 optically selected stars
located within ~2.5 pc of the namesake Trapezium stars
which define the center of the ONC.
Because of the large number and number density (~10^4 pc^-3) of stars,
the wide range in stellar mass (~0.1 - 50 Msun),
and the extreme youth (< 1 Myr) of the stellar population,
there is no better open cluster for investigating:
- the detailed shape of the initial mass spectrum;
- the apparent age spread in a region thought
to have undergone ``triggered" star formation;
- the time sequence of star formation as a function of stellar mass;
- the survival time of optically thick, inner circumstellar disks,
as a function of stellar mass; and
- trends of all of the above with cluster radius.
The massive stars of the ONC appear to have evacuated a cavity
which extends out of the molecular cloud in our direction, thus rendering
most of the stars likely to be dynamically associated with them
only slightly extincted (A_V < 2.5 mag).
This fact enables us to study the stellar population over its full range
in mass and age using an optical sample.
Friday, 4 October 1996
11:00am
Array Operations Center Auditorium
Local Host: Michael Rupen
Other NRAO/Socorro colloquia
mrupen@nrao.edu