Tracing the mass during low-mass star formation. I. Submillimeter continuum observations

Yancy L. Shirley, Neal J. Evans, Jonathan M.C. Rawlings, Erik M. Gregersen

Research output: Contribution to journalArticlepeer-review

213 Scopus citations


We have obtained 850 and 450 μm continuum maps of 21 low-mass cores with SEDs ranging from pre-protostellar to Class I (18 K < Tbol < 370 K), using SCUBA at the JCMT. In this paper we present the maps, radial intensity profiles, and photometry. Pre-protostellar cores do not have power-law intensity profiles, whereas the intensity profiles of Class O and Class I sources can be fitted with power laws over a large range of radii. A substantial number of sources have companion sources within a few arcminutes (two out of five pre-protostellar cores, nine out of 16 Class 0/1 sources). The mean separation between sources is 10,800 AU. The median separation is 18,000 AU including sources without companions as a lower limit. The mean value of the spectral index between 450 and 850 μm is 2.8 ± 0.4, with pre-protostellar cores having slightly lower spectral indices (2.5 ± 0.4). The mean mass of the sample, based on the dust emission in a 120″ aperture, is 1.1 ± 0.9 M. For the sources fitted by power-law intensity distributions (Iv(b)/Iv(0) = (b/b0)m), the mean value of m is 1.52 ± 0.45 for Class 0 and I sources at 850 μm and 1.44 ± 0.25 at 450 μm. Based on a simple analysis, assuming the emission is in the Rayleigh-Jeans limit and that Td(r) ∝ r-0.4, these values of m translate into power-law density distributions (n ∝ r-p) with p ∼ 2.1. However, we show that this result may be changed by more careful consideration of effects such as beam size and shape, finite outer radii, more realistic Td(r), and failure of the Rayleigh-Jeans approximation.

Original languageEnglish (US)
Pages (from-to)249-271
Number of pages23
JournalAstrophysical Journal, Supplement Series
Issue number1
StatePublished - Nov 2000


  • Brown dwarfs submillimeter
  • Stars: formation
  • Stars: low-mass

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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