Radio emission variability and proper motions of WR 112

Abstract

We analyzed 64 radio observations at the frequency of 8.4 GHz of the Wolf-Rayet star WR 112, taken from the Very Large Array archive. These observations cover a time baseline of 13 years, from June 2000 to July 2013. The radio structure of WR 112 is consistent with it being a point source in all the epochs and with its flux density varying from 0.6 mJy to 2.1 mJy. We tried to search for periodicities in these variations but our results were not conclusive. We also looked for extended emission from the infrared nebula that surrounds WR 112, settimg upper limits of 50 $\mu$Jy. Finally, we used the highest angular resolution images to measure the proper motions of WR 112, obtaining $\mu_\alpha\cos \delta = -2.6 \pm 1.1 \mbox{ mas yr$^{-1}$}$, and $\mu_\delta = -5.4 \pm 1.4 \mbox{ mas yr$^{-1}$}$. These proper motions are smaller than those previously reported, but still suggest significant peculiar motions for WR 112.