Radio continuum monitoring of the extreme carbon star IRC+10216

¹ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: kmenten,p309ekr@mpifr-bonn.mpg.de
² Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA e-mail: reid@cfa.harvard.edu
³ National Radio Astronomy Obsrvatory, Array Operations Center, PO Box O, Socorro, NM 87801, USA e-mail: mclausse@nrao.edu
⁴ Jet Propulsion Laboratory, MS 183-900, 4800 Oak Grove Drive, Pasadena, CA 91109, USA e-mail: raghvendra.sahai@jpl.nasa.gov

Received: 2 November 2005
Accepted: 15 March 2006

Abstract

We describe Very Large Array observations of the extreme carbon star IRC+10216 at 8.4, 14.9, and 22.5 GHz made over a two year period. We find possible variability correlated with the infrared phase and a cm- to sub-millimeter wavelength spectral index very close to 2. The variability, observed flux densities, and upper limit on the size are consistent with the emission arising from the stellar photosphere or a slightly larger radio photosphere.