Spitzer Space Telescope - General Observer Proposal #3337


Spitzer Observations of Newly Born Massive Stars in the W31 Cluster

Principal Investigator: Paul Crowther
           Institution: University of Sheffield

Co-Investigators: 
Peter Conti, University of Colorado                                   
Robert Blum, NOAO                                                     
Cassio Barbosa, IAG-USP, Sao Paulo                                    
Patrick Morris, IPAC                                                  
Schuyler van Dyk, IPAC                                                

Science Category: massive stars 
 Observing Modes: IracMap IrsStare 
  Hours Approved: 11.5 

Abstract:
We propose IRS spectroscopy and a small IRAC map of individual young,
massive stars in the giant HII region G10.2-0.3 within the W31 star
forming region.  Previous K-band observations by our team have
revealed the presence of O stars, massive young stellar objects,
ultra-compact HII regions, and featureless red sources, i.e.  a
snapshot of the earliest stages of massive star birth in a cluster.
What is the reason for these differences among the stellar content of
this cluster?  To make progress on our understanding of these very
early evolution stages it is imperative to tease out the properties of
the underlying stars.  We can obtain the integrated luminosities from
our K-band photometry, but stellar temperatures are more challenging,
requiring an analysis of nebular fine structure MIR lines of neon and
sulfur for which IRS spectroscopic datasets are critical.  We can also
study how the dust grains, possible mantled by ices, have been
processed in dense disks around these massive young stellar objects,
providing additional insights into the role that dust plays in young
star forming regions.