The progenitor of Nova Monocerotis 2012

ATel #4365; R. Greimel (U. Graz), J. Drew (U. Hertfordshire), D. Steeghs (U. Warwick), M. Barlow (UCL) on behalf of the IPHAS collaboration
on 10 Sep 2012; 11:49 UT
Credential Certification: Danny Steeghs (dsteeghs@cfa.harvard.edu)

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We report on the detection of the likely progenitor to Nova Mon 2012 using images from the INT Photometric H-Alpha Survey (IPHAS; http://www.iphas.org ). Nova Mon 2012 was discovered in the optical on August 9 (CBET #3202) and was recently found to be coincident with the gamma-ray transient Fermi J0639+0548 (ATel #4224, ATel #4310). Follow up observations of the Nova in the optical (ATel #4320),UV and X-Ray (Atel #4321) and radio (ATel #4352) were also recently reported.

The fields containing the classical nova were observed as part of our galactic plane survey using the Wide Field Camera (0.33"/pixel) at the 2.5m Isaac Newton Telescope. Seeing was stable around 1.1" for the observations which were calibrated using standard stars taken on the same night and corrected by the global survey calibration. The measurement are listed in the table below. Magnitudes are on the Vega scale and magnitude errors are dominated by the external global calibration error of 0.03 magnitudes.

Table of observations:

 
 Date and Time(UT) Field r     rerr i     ierr Ha    Haerr r-i  r-Ha 
 2004 11 4.2490    3743  18.05 0.03 17.39 0.04 17.58 0.04  0.66 0.47 
 2004 11 4.2521    3743o 17.92 0.03 17.24 0.04 17.59 0.04  0.68 0.33 
 2004 11 6.2153    3757  17.78 0.03 17.06 0.03 17.24 0.03  0.72 0.54 

A single point source was detected at the position of the nova. The variability of the nova counterpart is 5 times larger than that of surrounding stars. The r-Halpha colour index is about 0.5 and also shows variability. The nova progenitor lies above the main locus of fields stars implying mild Halpha line emission. The IPHAS counterpart coincides with the UKIDSS (Lucas et al., 2008, MNRAS 391, 136)) source UGPS J069978.60+055332.9 at J=16.26, H=15.71 and K=15.42. The next closest IPHAS point source is 6" away.

The total galactic extinction along the line of sight amounts to E(B-V)=0.8 (Schlafly & Finkbeiner 2011, ApJ 737, 103, dust-maps as well as our own field star photometry), while outburst spectroscopy indicates E(B-V)=0.3 (ATel #4320).

The IPHAS and UKIDSS colours are consistent with an early K SED reddened by E(B-V)=0.3 with an Halpha EW of 10-15 A (see also Drew et al. 2005, MNRAS 362, 752). If instead an optically thick accretion disk SED is assumed, it would require a reddening of E(B-V)=0.8, the maximum possible for this sightline, and Halpha EW of 15-20 A to be consistent with the IPHAS colours.

Acknowledgements: The Isaac Newton Telescope is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias

This research has made use of: the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration; the VizieR catalogue access tool, CDS, Strasbourg, France. The original description of the VizieR service was published in A&AS 143, 23