Multi-epoch radio continuum surveys of the Rho Ophiuchi dark cloud

Abstract

view Abstract Citations (61) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Multi-Epoch Radio Continuum Surveys of the Rho Ophiuchi Dark Cloud Stine, P. C. ; Feigelson, E. D. ; Andre, P. ; Montmerle, T. Abstract Radio-continuum surveys of 4 sq. deg of the ρ Ophiuchi cloud were conducted on four occasions at 1.4 GHz with the Very Large Array to study the variability of radio counterparts of over one hundred pre-main-sequence stars detected at X-ray, infrared, and optical wavelengths. These observations are supplemented with 5 GHz observations of the dense core region of the cloud and pointed observations of selected sources. This work significantly increases the sensitivity of a previous study by André, Montmerle, and Feigelson (1987), in which eight definite young stellar radio sources were uncovered. In this study, only one new reliable stellar source was found, located near the cloud core. The overwhelming majority (≡90%) of young stellar objects over a large area remain undetected to low flux-density levels (≡1 mJy). The failure to detect most PMS stars in ρ Ophiuchi and other star-formation regions may be explained by a sufficiently dense layer of circumstellar ionized material, such as a weak stellar wind, that absorbs nonthermal surface radio emission but is not itself detectable in radio. It seems that the stellar radio sources in the ρ Ophiuchi cloud are the prototypes of a new, rare class of young stellar objects. These sources are characterized by an absence of dense circumstellar ionized material and by extended magnetic structures with sizes ⪆3 stellar radii. Publication: The Astronomical Journal Pub Date: October 1988 DOI: 10.1086/114889 Bibcode: 1988AJ.....96.1394S Keywords: Early Stars; Ophiuchi Clouds; Pre-Main Sequence Stars; Sky Surveys (Astronomy); Stellar Flares; Very Large Array (Vla); Radio Emission; Stellar Activity; Stellar Mass; X Ray Sources; Astrophysics; STARS: PRE-MAIN-SEQUENCE full text sources ADS | data products SIMBAD (220)