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Title: THE GOULD's BELT VERY LARGE ARRAY SURVEY. I. THE OPHIUCHUS COMPLEX

We present large-scale (∼2000 arcmin{sup 2}), deep (∼20 μJy), high-resolution (∼1'') radio observations of the Ophiuchus star-forming complex obtained with the Karl G. Jansky Very Large Array at λ = 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 Güdel-Benz relation, but with a different normalization than the most radioactive types of stars. Finally, we detect a ∼70 mJy compactmore » extragalactic source near the center of the Ophiuchus core, which should be used as gain calibrator for any future radio observations of this region.« less
Authors:
; ; ; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México Apartado Postal 3-72, 58090 Morelia, Michoacán (Mexico)
  2. National Radio Astronomy Observatory, Domenici Science Operations Center, 1003 Lopezville Road, Socorro, NM 87801 (United States)
  3. Paul Harris 9065, Las Condes, Santiago (Chile)
  4. Division of Physics, Math, and Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
  5. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105 (United States)
  6. Department of Astronomy, The University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712 (United States)
  7. Centro de Investigaciones de Astronomía, Mérida 5101-A (Venezuela, Bolivarian Republic of)
  8. National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)
Publication Date:
OSTI Identifier:
22270950
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 775; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; DWARF STARS; INDEXES; MAGNETIC FIELDS; POLARIZATION; QUASARS; RADIOASTRONOMY; RESOLUTION; T TAURI STARS