Spitzer Space Telescope - General Observer Proposal #30384


Going Long:  Studying the Initial Conditions for Brown Dwarfs and
Low-Mass Stars with Spitzer at 160  microns

Principal Investigator: Tyler Bourke
           Institution: Harvard-Smithsonian Center for Astrophysics

Co-Investigators: 
Philip Myers, Harvard-Smithsonian Center for Astrophysics             
Neal Evans II, University of Texas at Austin                          
Michael Dunham, University of Texas at Austin                         
Deborah Padgett, Spitzer Science Center                               
Jes Jorgensen, Harvard-Smithsonian Center for Astrophysics            
Yancy Shirley, Steward Observatory                                    
Tracy Huard, Harvard-Smithsonian Center for Astrophysics              
Tim Brooke, Caltech                                                   
Jens Kauffmann, Max-Planck-Institut fur Radioastronomie               

Science Category: star formation 
 Observing Modes: MipsScan 
  Hours Approved: 47.3 

Abstract:
We propose to obtain 160  micron maps of 13 dense cores with faint
embedded sources (VeLLOs) and of 27 cores which lack sources.  These
cores were already mapped by Spitzer at shorter wavelengths, and by
ground based telescopes at longer wavelengths.  They have no
observations near 160  microns, so their peak flux and total
luminosities are very uncertain, as are the effects of the ISRF on
their temperature stucture.  Our proposed observations will determine
each spectrum and its luminosity accurately enough to separate the
contributions from internal and external heating.  With current data,
several of the embedded sources have luminosity < 0.1 Lsun, among the
lowest known, which indicates substellar masses according to simple
accretion models.  Our more accurate luminosities will be used to
estimate whether these sources have masses of brown dwarfs or of
stars, and the related question of whether these sources have mass
accretion rates expected from the standard model of low-mass star
formation.