HERSCHEL dust emission as a probe of starless cores mass: MCLD 123.5+24.9 of the polaris flare

Gururaj A. Wagle, Thomas H. Troland, Gary J. Ferland, Nicholas P. Abel

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We present newly processed archival Herschel images of molecular cloud MCLD 123.5+24.9 in the Polaris Flare. This cloud contains five starless cores. Using the spectral synthesis code Cloudy, we explore uncertainties in the derivation of column densities, and hence masses of molecular cores from Herschel data. We first consider several detailed grain models that predict far-infrared grain opacities. Opacities predicted by the models differ by more than a factor of two, leading to uncertainties in derived column densities by the same factor. Then we consider uncertainties associated with the modified blackbody fitting process used by observers to estimate column densities. For high column density clouds (N(H) 蠑 1 cm-2), this fitting technique can underestimate column densities by about a factor of three. Finally, we consider the virial stability of the five starless cores in MCLD 123.5+24.9. All of these cores appear to have strongly sub-virial masses, assuming, as we argue, that 13CO line data provide reliable estimates of velocity dispersions. Evidently, they are not self-gravitating, so it is no surprise that they are starless.

Original languageEnglish
Article number17
JournalAstrophysical Journal
Issue number1
StatePublished - Aug 10 2015

Bibliographical note

Publisher Copyright:
� 2015. The American Astronomical Society. All rights reserved..


  • ISM: abundances
  • ISM: clouds
  • dust, extinction
  • infrared: ISM
  • photon-dominated region (PDR)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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