Spitzer Space Telescope - General Observer Proposal #20778


A Young Stellar and Protostellar Census of Galactic Ultracompact HII
Regions -- Exploring Massive Star Formation with MIPS and IRAC

Principal Investigator: Sean Carey
           Institution: SSC

Co-Investigators: 
Jeonghee Rho, Spitzer Science Center / Caltech                        
Peter Conti, JILA / University of Colorado                            
Paul Crowther, University of Sheffield                                
Alberto Noreiga-Crespo, Spitzer Science Center / Caltech              

Science Category: massive stars 
 Observing Modes: IracMap MipsPhot MipsSed 
  Hours Approved: 13.0 

Abstract:
We will map regions around 41 ultracompact HII (UCHII) regions from
the radio selected Midcourse Space Experiment (MSX) sample of Crowther
& Conti (2003) using IRAC and MIPS to (i) determine their embedded
source contents;  (ii) the multiplicity of high mass star formation
and (iii) estimate the initial mass function of the sample.  Our
sample spans a range of UCHII morphology and Galactic environment.
The proposed observations will detect all massive star formation
ongoing in these objects and permit robust determination of the number
of stars powering each UCHII, in contrast with previous mid-IR
observations which were poorly spatially matched with radio
observations.  Deep imaging with IRAC will look for molecular line
emission associated with shocked massive outflows, and MIPS
observations will be critical to detect the earliest and most massive
protostars and to construct the spectral energy distributions of the
protostars.  The data will be used to examine various theories of
massive star formation and to examine the role of triggered star
formation in these early massive objects.