The Gould's Belt Very Large Array Survey. I. The Ophiuchus Complex

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2013-09

Authors

Dzib, Sergio A.
Loinard, Laurent
Mioduszewski, Amy J.
Rodriguez, Luis F.
Ortiz-Leon, Gisela N.
Pech, Gerardo
Rivera, Juana L.
Torres, Rosa M.
Boden, Andrew F.
Hartmann, Lee

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Abstract

We present large-scale (similar to 2000 arcmin(2)), deep (similar to 20 mu Jy), high-resolution (similar to 1 '') radio observations of theOphiuchus star-forming complex obtained with the Karl G. Jansky Very Large Array at lambda = 4 and 6 cm. In total, 189 sources were detected, 56 of them associated with known young stellar sources, and 4 with known extragalactic objects; the other 129 remain unclassified, but most of them are most probably background quasars. The vast majority of the young stars detected at radio wavelengths have spectral types K or M, although we also detect four objects of A/F/B types and two brown dwarf candidates. At least half of these young stars are non-thermal (gyrosynchrotron) sources, with active coronas characterized by high levels of variability, negative spectral indices, and (in some cases) significant circular polarization. As expected, there is a clear tendency for the fraction of non-thermal sources to increase from the younger (Class 0/I or flat spectrum) to the more evolved (Class III or weak line T Tauri) stars. The young stars detected both in X-rays and at radio wavelengths broadly follow a Gudel-Benz relation, but with a different normalization than the most radioactive types of stars. Finally, we detect a similar to 70 mJy compact extragalactic source near the center of the Ophiuchus core, which should be used as gain calibrator for any future radio observations of this region.

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Dzib, Sergio A., Laurent Loinard, Amy J. Mioduszewski, Luis F. Rodr�guez, Gisela N. Ortiz-Le�n, Gerardo Pech, Juana L. Rivera et al. "The Gould's Belt Very Large Array Survey. I. The Ophiuchus Complex." The Astrophysical Journal, Vol. 775, No. 1 (Sep., 2013): 63.