Comparing Star Formation on Large Scales in the c2d Legacy Clouds: Bolocam 1.1 mm Dust Continuum Surveys of Serpens, Perseus, and Ophiuchus

Abstract

We have undertaken an unprecedentedly large 1.1 millimeter continuum survey of three nearby star forming clouds using Bolocam at the Caltech Submillimeter Observatory. We mapped the largest areas in each cloud at millimeter or submillimeter wavelengths to date: 7.5 deg 2 in Perseus (Paper I), 10.8 deg 2 in Ophiuchus (Paper II), and 1.5 deg 2 in Serpens with a resolution of 31 ′′ , detecting 122, 44, and 35 cores, respectively. Here we report on results of the Serpens survey and compare the three clouds. Average measured angular core sizes and their dependence on resolution suggest that many of the observed sources are consistent with power-law density profiles. Tests of the effects of cloud distance reveal that linear resolution strongly affects measured source sizes and densities, but not the shape of the mass distribution. Core mass distribution slopes in Perseus and Ophiuchus (α = 2.1 ± 0.1 and α = 2.1 ± 0.3) are consistent with recent measurements of the stellar IMF, whereas the Serpens distribution is flatter (α = 1.6 ± 0.2). We also compare the relative mass distribution shapes to predictions from turbulent fragmentation simulations. Dense cores constitute less than 10% of the total cloud mass in all three clouds, consistent with other measurements of low star-formation efficiencies. Furthermore, most cores are found at high column densities; more than 75% of 1.1 mm cores are associated with A V 8 mag in Perseus, 15 mag in Serpens, and 20 − 23 mag in Ophiuchus.

Dust, ice and gas in time (DIGIT):HerschelandSpitzerspectro-imaging of SMM3 and SMM4 in Serpens

“…Fluxes for both instruments are extracted within a region encompassing the 3 × 3 central spaxels of PACS. Filled circles are flux densities from IRAC at 3.6, 4.5, 5.8, and 8.0 μm bands (red, Harvey et al 2007), MIPS at 24 and 70 μm (blue, Harvey et al 2007), SCUBA at 450 and 850 μm, (green, Davis et al 1999) and 1100 μm (black, Enoch et al 2007). Red arrows represent upper limit values for the IRAC bands.…”

Planckearly results. XXIII. The first all-sky survey of Galactic cold clumps

“…Netterfield et al (2009) show that the BLAST sources present the same behaviour, with a ratio between the inferred source size and the BLAST beam equal to 1.1. Enoch et al (2007) obtained a value of 1.5 for cold cores in Serpens, Perseus and Ophiucus observed with Bolocam. Indeed these compact sources are associated with larger envelopes, presenting radial density profiles described by power laws with an exponent in the range −2 to −1 (Young et al 2003).…”

“…We find that θ i /θ PSF ≈ 1.4, and can conclude that we have resolved the sources. Nevertheless, as pointed out by Enoch et al (2007) and Netterfield et al (2009), the fact that the cold sources are mostly extended compared to the PSF may be an indicator of the hierarchical structure of these objects. Netterfield et al (2009) show that the BLAST sources present the same behaviour, with a ratio between the inferred source size and the BLAST beam equal to 1.1.…”

Submillimetre Studies of Prestellar and Starless Cores in the Ophiuchus, Taurus and Cepheus Molecular Clouds

“…The distribution of prestellar core masses is known as the Core Mass Function (CMF). An IMF-like CMF -a powerlaw distribution at high masses, with a turnover at low masses -has been found in all nearby star-forming molecular clouds for which a CMF has been observed, including Ophiuchus (Motte et al 1998;Johnstone et al 2000;Enoch et al 2007),…”