Spitzer Space Telescope - Guaranteed Time Observer Proposal #50519


An Unbiased Survey of the Gem OB1 Molecular Cloud Complex

Principal Investigator: Giovanni Fazio
           Institution: Harvard-Smithsonian Astrophysical Observatory

     Technical Contact: Lori Allen, Smithsonian Astrophysical Observatory

Co-Investigators: 
Lori Allen, SAO                                                       
Robert Gutermuth, SAO                                                 
Dawn Peterson, SAO                                                    
Tom Megeath, University of Toledo                                     
James Muzerolle, University of Arizona                                

Science Category: star formation 
 Observing Modes: MipsScan 
  Hours Approved: 43.2 

Abstract:
We propose an unbiased 24 micron survey of the Giant Molecular Cloud complex
known as Gem~OB1. Unlike the nearby dark clouds surveyed by Spitzer Legacy
teams, GMCs are responsible for most of the star formation in the Galaxy and
therefore are more representative of the typical birthplace of stars. The
Gem~OB1 cloud lies toward the outer Galaxy where the Galactic background and
line-of sight extinction are both low, and near enough that its solar-mass
protostars are easily detectable by Spitzer. Gem~OB1 is notable for its multiple
bubble like structures and other complex morphologies seen in molecular gas.
The proposed 24 micron data will be used to identify protostars throughout the
cloud, and will be combined with data from subsequent surveys to study the
distribution of T-Tauri stars, the evolution of protostellar envelopes and
disks, and the demographics of stellar masses and ages in the Gem~OB1 GMC. The
proposed 24 micron measurements are essential for identifying embedded
protostars, and for characterizing disk evolution, especially in older systems
that are evolving from protoplanetary to debris disks. This survey will "set the
stage" for a Spitzer warm mission follow-up project, aimed at further
characterizing the young stars in Gem~OB1.