Maps of the thermal emission from dust in nearby star-forming regions have revealed an apparent similarity between the mass distributions of dense cores (CMF) and the stellar initial mass function (IMF). Deriving the mass of a core from measurements of dust emission is not straightforward, however. The primary difficulty comes from uncertainty in the dust emissivity, and in particular the slope of the dust emissivity at long wavelengths (the emissivity spectral index). Ground-based observations of the continuum emission from cores suffer from atmospheric contamination, so the best way to derive the emissivity spectral index is from space-based observations. Through our successful OT1 proposal (OT1_sschnee_1) we are mapping the spectral energy distribution (SED) of 11 cores in nearby molecular clouds using SPIRE/FTS to determine their masses accurately and constrain the emissivity spectral index of the dust emission. Now we propose to add a unique and interesting target to our sample and acquire similar data toward L1689-SMM16, a starless core newly identified to be on the brink of star formation. These observations will be supplemented with recently acquired GBT ammonia observations of the same region to break the degeneracy between temperature and the emissivity spectral index inherent in SED fits. The proposed data will enable us to derive much more accurate core masses, test the similarity between the CMF and the IMF, and search for variations of the dust properties with environmental factors such as temperature and density.
Publication
Instrument
SPIRE_SpireSpectrometer_
Temporal Coverage
2012-09-24T10:05:31Z/2012-09-24T10:34:38Z
Version
SPG v14.1.0
Mission Description
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
