Grain alignment in starless cores

T. J. Jones, M. Bagley, M. Krejny, B. G. Andersson, P. Bastien

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55 Scopus citations


We present near-IR polarimetry data of background stars shining through a selection of starless cores taken in the K band, probing visual extinctions up to . We find that continues to decline with increasing AV with a power law slope of roughly -0.5. Examination of published submillimeter (submm) polarimetry of starless cores suggests that by the slope for P versus τ becomes ∼-1, indicating no grain alignment at greater optical depths. Combining these two data sets, we find good evidence that, in the absence of a central illuminating source, the dust grains in dense molecular cloud cores with no internal radiation source cease to become aligned with the local magnetic field at optical depths greater than . A simple model relating the alignment efficiency to the optical depth into the cloud reproduces the observations well.

Original languageEnglish (US)
Article number31
JournalAstronomical Journal
Issue number1
StatePublished - Jan 1 2015

Bibliographical note

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


  • ISM: clouds
  • ISM: magnetic fields
  • dust extinction


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