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Discovery of ten galactic Nova candidates in the VVV disk area

ATel #8602; R. K. Saito (Universidade Federal de Sergipe), D. Minniti (Univ. Andres Bello, Millennium Institute of Astrophysics, Vatican Observatory), M. Catelan (Pontificia Univ. Catolica de Chile, Millennium Institute of Astrophysics), R. Angeloni (Gemini Observatory), J. C. Beamin (Univ. de Valparaiso, Millennium Institute of Astrophysics), T. Palma (Univ. Andres Bello, Millennium Institute of Astrophysics), L. A. Gutierrez (Univ. Andres Bello, Millennium Institute of Astrophysics), K. Montenegro (Univ. Andres Bello, Millennium Institute of Astrophysics)
on 29 Jan 2016; 01:26 UT
Credential Certification: Roberto Saito (saito@ufs.br)

Subjects: Infra-Red, Cataclysmic Variable, Nova, Transient

We report the discovery of ten likely Galactic novae by the VVV Survey in its disk area (vvvsurvey.org; Minniti et al. 2010, New Astronomy, 15, 433). A search for high-amplitude transients on the VVV disk data taken during the 2010-2013 seasons detected the presence of ten stellar sources fading in brightness by at least Delta_Ks=3 mag with their light curves following the expected behavior of a nova outburst. The table below presents the main information about each nova candidate.

 
  Object         RA         DEC          l      b       Eruption date         Delta_Ks  Ks_mag and date     A_V             
VVV-NOV-008  17:00:09.93 -44:55:36.8  -18.281 -1.602  before Mar 06 2010         4.5   13.14 (08-19-2013)  10.48  
VVV-NOV-009  17:05:01.28 -43:42:34.3  -16.786 -1.546  before Mar 06 2010         6.5  >17.7  (08-19-2013)   9.74 
VVV-NOV-010  17:16:35.31 -38:39:18.4  -11.425 -0.305  before Mar 29 2010         4.4   15.86 (09-30-2013)  21.24 
VVV-NOV-011  15:55:58.86 -53:32:19.7  -31.697 -0.013  before Apr 19 2010         3.3   15.36 (07-21-2013)  63.66 
VVV-NOV-012  16:25:27.57 -47:53:09.7  -24.440  0.957  Mar 02 2010 - Aug 15 2010  9.2  >17.6  (07-28-2013)  13.41 
VVV-NOV-013  16:34:03.64 -47:45:06.4  -23.348  0.003  Jun 26 2010 - May 15 2011  6.4  >17.6  (07-31-2013)  71.72 
VVV-NOV-014  13:28:04.81 -61:13:43.8  -52.672  1.329  Aug 17 2010 - Jul 30 2011  3.6   16.57 (07-29-2013)   6.68 
VVV-NOV-015  16:32:47.88 -47:03:04.6  -22.980  0.635  Sep 13 2011 - Mar 09 2012  3.7   14.08 (07-29-2013)  14.36 
VVV-NOV-016  16:00:09.64 -53:51:09.7  -31.429 -0.653  Mar 29 2012 - May 21 2012  6.4   14.69 (07-21-2013)  26.67 
VVV-NOV-017  16:51:44.54 -41:48:58.4  -16.815  1.539  Jul 01 2012 - Jun 25 2013  3.6  >17.9  (08-06-2013)  10.35 
The eruption dates are estimated by the interval between the latest observation in quiescence (or with no detection) and the first observation in eruption. Delta_Ks is the total amplitude in the VVV data and Ks_mag is the magnitude of the latest observation available after eruption. A_V is the mean extinction estimated from the Schlegel et al. (1998) maps for a 5 arcmin region around the target position. We notice the extinction in the optical reaches up to 71 mag.

WISE data show a stellar source at the same position of VVV-NOV-008. In the All WISE catalogue VVV-NOV-008 corresponds to J170009.92-445536.8 (0.078 arcsec apart), with magnitudes W1=8.036, W2=7.642, W3=6.602 and W4=5.631. VVV-NOV-009 has also a counterpart in the WISE data. In the All WISE catalogue VVV-NOV-009 corresponds to J170501.31-434234.8 (0.664 arcsec apart), with magnitudes W1=4.472, W2=1.995, W3=0.671 and W4=0.122.

VVV-NOV-010 corresponds to the All WISE source J171635.29-383918.5 (0.243 arcsec apart), with magnitudes W1=8.942, W2=7.580, W3=3.045 and W4=1.428. VVV-NOV-011 corresponds to the All WISE source J155558.87-533219.7 (0.161 arcsec apart), with magnitudes W1=11.281 and W2=10.285.

VVV-NOV-012 has two nearby sources (within about 1 arcsec) which are in the 2MASS and WISE catalogues. However, a visual inspection on the VVV images suggests the progenitor/remnant is a different source, beyond detection in the latest 2013 observations.

The progenitor of VVV-NOV-014 is seen in the VVV data during the 2010 season as a faint source with Ks=16.80 mag and (J-Ks)=1.56. The progenitor of VVV-NOV-016 is observed during the 2010-2012 seasons at Ks=15.72 mag and (J-Ks)=0.84.

There are no previous entries in the literature for the position of VVV-NOV-013, VVV-NOV-015 and VVV-NOV-017.

Spectroscopic follow-up observations are encouraged in order to confirm the nature of the candidates.

Acknowledgments: We gratefully acknowledge use of data from the ESO Public Survey programme ID 179.B-2002 taken with the VISTA telescope, and data products from the Cambridge Astronomical Survey Unit. R.K.S. acknowledges support from CNPq/Brazil.