Spitzer Space Telescope - General Observer Proposal #40569


Completing the IRS spectroscopy of young massive protostars

Principal Investigator: Stephan Birkmann
           Institution: Max-Planck-Institut fuer Astronomie

     Technical Contact: Martin Hennemann, Max-Planck-Institut fuer Astronomie

Co-Investigators: 
Martin Hennemann, Max-Planck-Institut fuer Astronomie                 
Juergen Steinacker, Max-Planck-Institut fuer Astronomie               
Dietrich Lemke, Max-Planck-Institut fuer Astronomie                   

Science Category: star formation 
 Observing Modes: IrsStare 
  Hours Approved: 2.2 

Abstract:
This proposal is a partial resubmission of the Cycle-3 program 30919, PI S.
Birkmann. Two targets of that program were not observed because of an error
during peak-up acquisition. Our initial sample consists of 13 massive
pre-stellar core candidates established using the ISOPHOT Serendipity Survey
(ISOSS) and submm and molecular line observations. These were successfully
observed with IRAC and MIPS during GO Cycle-2, and despite their early
evolutionary stage indicated by low dust and gas kinetic temperatures all of
them show embedded 24 um sources that may correspond to extremely young
protostellar objects. To be able to characterize the physical conditions in the
discovered MIR sources we selected a subsample of six objects for follow-up IRS
observations in Cycle-3 which are partly accomplished. Based on the Spitzer
photometric data they are believed to represent different evolutionary stages,
and the two sources not observed constitute the most extreme cases. Via
radiative transfer modeling and warm gas diagnostics we aim to identify the
nature of the discovered sources and place them in an evolutionary context. To
achieve this, it is mandatory to include the missing sources and therefore we
propose to carry out the observations towards them.