350 μm map of the Ophiuchus molecular cloud: core mass function
Stars are born in dense cores of molecular clouds. The core mass function (CMF), which is the mass distribution of dense cores, is important for understanding the stellar initial mass function (IMF). We obtained 350 μm dust continuum data using the SHARC-II camera at the Caltech Submillimeter Observatory (CSO) telescope. A 350 μm map covering 0.25 deg2 of the Ophiuchus molecular cloud was created by mosaicing 56 separate scans. The CSO telescope had an angular resolution of 9″, corresponding to 1.2 × 103 AU at the distance of the Ophiuchus molecular cloud (131 pc). The data was reduced using the Comprehensive Reduction Utility for SHARC-II (CRUSH). The flux density map was analyzed using the GaussClumps algorithm, within which 75 cores has been identified. We used the Spitzer c2d catalogs to separate the cores into 63 starless cores and 12 protostellar cores. By locating Jeans instabilities, 55 prestellar cores (a subcategory of starless cores) were also identified. The excitation temperatures, which were derived from FCRAO 12CO data, help to improve the accuracy of the masses of the cores. We adopted a Monte Carlo approach to analyze the CMF with two types of functional forms; power law and log-normal. The whole and prestellar CMF are both well fitted by a log-normal distribution, with µ = −1.18 ± 0.10, σ = 0.58 ± 0.05 and µ = 1.40 ± 0.10, σ = 0.50 ± 0.05 respectively. This finding suggests that turbulence influences the evolution of the Ophiuchus molecular cloud.
KeywordsISM molecular clouds Ophiuchus CMF
Unable to display preview. Download preview PDF.
- 3.Ward-Thompson D, Andre P, Crutcher R, et al. Protostars and Planets V. Reipurth B, Jewitt D, Keil K, eds. Tucson, Arizona: The University of Arizona Press, 2007Google Scholar
- 22.Pilbratt G L, Riedinger J R, Passvogel T, et al. Herschel space observatory. An ESA facility for far-infrared and submillimetre astronomy. Astron Astrophys, 2010, 518Google Scholar
- 24.Kovács A. Scanning strategies for imaging arrays. Proc Int Soc Opt Photon, 2008, 7020: 702007Google Scholar
- 25.Kovács A. CRUSH: Fast and scalable data reduction for imaging arrays. Int Soc Opt Photon, 2008, 7020: 70201SGoogle Scholar
- 36.Evans, Harvey M M, Huard T L, et al. Final delivery of data from the c2d legacy project: IRAC and MIPS. Pasadena, CA: SSC, 2007Google Scholar
- 37.Lomax O D. Simulations of Star Formation in Ophiuchus. Dissertation for the Doctoral Degree. Wales, UK: Cardiff University, 2013Google Scholar
- 47.Ballesteros-Paredes J, Klessen R S. Molecular cloud turbulence and star formation. Protostars and Planets V. Reipurth B, Jewitt D, Keil K, eds. Tucson, Arizona: The University of Arizona Press, 2007Google Scholar