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Title: Time monitoring of radio jets and magnetospheres in the nearby young stellar cluster R Coronae Australis

We report Karl G. Jansky Very Large Array 8-10 GHz (λ = 3.0-3.7 cm) monitoring observations toward the young stellar object (YSO) cluster R Coronae Australis (R CrA), taken from 2012 March 15 to 2012 September 12. These observations were planned to measure the radio flux variabilities in timescales from 0.5 hr to several days, to tens of days, and up to ∼200 days. We found that among the YSOs detectable in individual epochs, in general, the most reddened objects in the Spitzer observations show the highest mean 3.5 cm Stokes I emission, and the lowest fractional variabilities on <200 day timescales. The brightest radio flux emitters in our observations are the two reddest sources IRS7W and IRS7E. In addition, by comparing our observations with observations taken from 1996 to 1998 and 2005, we found that the radio fluxes of these two sources have increased by a factor of ∼1.5. The mean 3.5 cm fluxes of the three Class I/II sources, IRSI, IRS2, and IRS6, appear to be correlated with their accretion rates derived by a previous near-infrared line survey. The weakly accreting Class I/II YSOs, or those in later evolutionary stages, present radio flux variability on <0.5 hr timescales.more » Some YSOs were detected only during occasional flaring events. The source R CrA went below our detection limit during a few fading events.« less
Authors:
; ; ; ; ;  [1] ; ; ;  [2] ;  [3] ;  [4] ;  [5]
  1. Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei, 106, Taiwan (China)
  2. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748, Garching (Germany)
  3. Department of Astrophysics, University of Vienna, Türkenschanzstraße 17, A-1180, Vienna (Austria)
  4. Centro de Radioastronomía y Astrofísica, UNAM, A.P. 3-72, Xangari, Morelia, 58089 (Mexico)
  5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22348223
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; EMISSION; FLARING; GHZ RANGE; MAGNETIC FIELDS; SENSITIVITY; STAR EVOLUTION; STARS