An infrared through radio study of the properties and evolution of IRDC clumps

Cara Battersby, John Bally, James M. Jackson, Adam Ginsburg, Yancy L. Shirley, Wayne Schlingman, Jason Glenn

Research output: Contribution to journalArticlepeer-review

71 Scopus citations


We examine the physical properties and evolutionary stages of a sample of 17 clumps within 8 Infrared Dark Clouds (IRDCs) by combining existing infrared, millimeter, and radio data with new Bolocam Galactic Plane Survey (BGPS) 1.1 mm data, Very Large Array radio continuum data, and Heinrich Hertz Telescope dense gas (HCO+ and N2H+) spectroscopic data. We combine literature studies of star formation tracers and dust temperatures within IRDCs with our search for ultracompact (UC) HII regions to discuss a possible evolutionary sequence for IRDC clumps. In addition, we perform an analysis of mass tracers in IRDCs and find that 8μm extinction masses and 1.1 mm BGPS masses are complementary mass tracers in IRDCs except for the most active clumps (notably those containing UC Hii regions), for which both mass tracers suffer biases. We find that the measured virial masses in IRDC clumps are uniformly higher than the measured dust continuum masses on the scale of ∼1 pc. We use 13CO, HCO+, and N2H+ to study the molecular gas properties of IRDCs and do not see any evidence of chemical differentiation between hot and cold clumps on the scale of ∼1 pc. However, both HCO+ and N2H+ are brighter in active clumps, due to an increase in temperature and/or density. We report the identification of four UC HII regions embedded within IRDC clumps and find that UC Hii regions are associated with bright (≳1 Jy) 24μm point sources, and that the brightest UC HII regions are associated with "diffuse red clumps" (an extended enhancement at 8μm). The broad stages of the discussed evolutionary sequence (from a quiescent clump to an embedded HII region) are supported by literature dust temperature estimates; however, no sequential nature can be inferred between the individual star formation tracers.

Original languageEnglish (US)
Pages (from-to)222-250
Number of pages29
JournalAstrophysical Journal
Issue number1
StatePublished - Sep 20 2010


  • Dust
  • Extinction
  • ISM: clouds
  • Stars: formation
  • Stars: pre-main sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'An infrared through radio study of the properties and evolution of IRDC clumps'. Together they form a unique fingerprint.

Cite this