Detection of Rising Radio Emission from V745 Sco

ATel #5884; M. P. Rupen, A. J. Mioduszewski (NRAO), L. Chomiuk (MSU),J. Sokoloski (Columbia), T. Nelson (Minnesota), K. Mukai (UMBC/GSFC)
on 12 Feb 2014; 16:24 UT
Credential Certification: Michael P. Rupen (mrupen@nrao.edu)

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Observations with the Karl G. Jansky Very Large Array (VLA) have detected a rapid increase in radio flux density from the recurrent nova V745 Sco (CBET 3803; AAVSO Special Notice 380) within two days of the optical outburst (2014 February 6.7).

UTC	Frequency	Flux Density
	(GHz)	(mJy)
2014 Feb 8.7	4.56	0.13+/-0.01
2014 Feb 8.7	7.38	0.24+/-0.01
2014 Feb 9.7	4.56	0.28+/-0.01
2014 Feb 9.7	7.38	0.40+/-0.01
2014 Feb 9.7	28.2	2.4 +/-0.04
2014 Feb 9.7	36.5	2.5 +/-0.04

The error bars here are statistical only; systematic errors are 10--20% for these preliminary data reductions.

The rising spectrum is consistent with optically thick thermal or self-absorbed synchrotron emission. For a distance of 7.3+/-1.2 kpc (Schaefer 2009 ApJ 697, 721) and radial expansion speeds of order 4500 km/s (e.g., ATel #5874), the brightness temperature must be at least 10^6 K. Such an early detection is reminiscent of the initial fast rise seen in the 2006 outburst of the recurrent symbiotic nova RS Oph (Eyres et al. 2009 MNRAS 395, 1533).

Radio monitoring with the VLA is on-going; we note that Hjellming detected several-mJy, flat spectrum radio emission from V745 Sco in 1989, over a month after its previous outburst (IAUC 4853 ).

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

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