Title:   Submillimeter Observations of An Isolated Massive Dense Core

Speaker:         Hiroko Shinnaga (CSO)

Abstract:

Understanding massive star formation and the evolution is an important
subject in the field of astrophysics.  High mass star formation is poorly
understood because high mass young stars are deeply embedded in
their natal dense cores and high mass stars form and evolve in a short
time scale.  We identified an isolated massive dense core in an early
phase of massive star formation with a simple configulation and carried
out a detail observational study on the dense core.  The massive dense
core hosts an early B type massive (proto)star, IRAS 20126+4104.  I'll
present the highlights of the study, mainly done using the 10.4 meter
Leighton telescope at the Caltech Submillimeter Observatory (CSO).
Submillimeter continuum (350- and 450 micron) and CO 6-5 line
observations have obtained at the CSO.  The flux ratio map made
from the submillimeter continuum revealed complex features of the core.
CO 6-5 observations revealed narrow line width molecular components
in the envelope that shows a velocity gradient, probably due to the rotation.
The enclosed core mass is estimated to be ~ 200 Msun.  The rotation
axis of the core envelope over a  ~1pc scale is almost opposite sense
of that of the disk like feature with a scale of 0.06 pc associated with
the massive (proto)star.  In addition, we identified clumps (substructures)
in the core using interferometric CO 1-0 observations, taken at the the
Owens Valley Millimeter Array at Caltech, and found most of the clumps
show flux enhancement on the 350 micron continuum image.  The clump
mass distribution is investigated over a range of 0.01 -- 40 Msun and
found to have a shallow power index (-1.6 +/- 0.4).