First Detection of T Pyx in the Radio

ATel #3318; L. Chomiuk (CfA/NRAO), M. I. Krauss (NRAO), J. L. Sokoloski (Columbia U.), M. P. Rupen, A. J. Mioduszewski, N. Roy (NRAO), T. J. O'Brien (U. of Manchester), M. F. Bode (Liverpool John Moores U.), S. P. S. Eyres (U. of Central Lancashire)
on 2 May 2011; 18:15 UT
Credential Certification: Laura Chomiuk (lchomiuk@cfa.harvard.edu)

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We report an EVLA radio continuum detection of the recurrent nova T Pyx, which was discovered to be in outburst on 2011 April 14 (CBET #2700, IAUC # 9205 ). The EVLA detected T Pyx on May 1.1 at 33.1 GHz with a flux density of 248 +/- 32 microJy. One week earlier, on April 22.9, we measured a flux density of 16 +/- 30 microJy at this frequency, which we take to be a non-detection.
In addition, we observed T Pyx at 5.9 GHz on both dates, but it was not detected in either epoch, consistent with ATel #3310. The formal 5.9-GHz flux densities are 3.1 +/- 8.0 microJy on April 22.0 and 27 +/- 11 microJy on April 30.9.
On May 1.1, T Pyx had a spectral index (S_&nu &prop &nu^&alpha) of &alpha > 1.2, consistent with the optically-thick thermal emission expected from the early stages of expanding nova ejecta. Assuming T Pyx is optically thick with a brightness temperature of 10^4 K and expanding with spherical symmetry and a velocity of 1800 km/s (IAUC # 9205 ), our 33.1 GHz measurement implies a distance of 5.5 kpc.
We plan to continue monitoring T Pyx with the EVLA, and will post updated results on our EVLA nova webpage.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We are grateful to the EVLA commissioning team.

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