ALMA Observations of Starless Core Substructure in Ophiuchus

H. Kirk, M. M. Dunham, J. Di Francesco, D. Johnstone, S. S.R. Offner, S. I. Sadavoy, J. J. Tobin, H. G. Arce, T. L. Bourke, S. Mairs, P. C. Myers, J. E. Pineda, S. Schnee, Y. L. Shirley

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16 Scopus citations

Abstract

Compact substructure is expected to arise in a starless core as mass becomes concentrated in the central region likely to form a protostar. Additionally, multiple peaks may form if fragmentation occurs. We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 2 observations of 60 starless and protostellar cores in the Ophiuchus molecular cloud. We detect eight compact substructures which are from the nearest Spitzer young stellar object. Only one of these has strong evidence for being truly starless after considering ancillary data, e.g., from Herschel and X-ray telescopes. An additional extended emission structure has tentative evidence for starlessness. The number of our detections is consistent with estimates from a combination of synthetic observations of numerical simulations and analytical arguments. This result suggests that a similar ALMA study in the Chamaeleon I cloud, which detected no compact substructure in starless cores, may be due to the peculiar evolutionary state of cores in that cloud.

Original languageEnglish (US)
Article number114
JournalAstrophysical Journal
Volume838
Issue number2
DOIs
StatePublished - Apr 1 2017

Keywords

  • Stars: formation
  • submillimeter: ISM

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Kirk, H., Dunham, M. M., Francesco, J. D., Johnstone, D., Offner, S. S. R., Sadavoy, S. I., Tobin, J. J., Arce, H. G., Bourke, T. L., Mairs, S., Myers, P. C., Pineda, J. E., Schnee, S., & Shirley, Y. L. (2017). ALMA Observations of Starless Core Substructure in Ophiuchus. Astrophysical Journal, 838(2), [114]. https://doi.org/10.3847/1538-4357/aa63f8