March 15, 2010: According to CBET 2199, 2204, and 2205, the suspected symbiotic star V407 Cyg has been observed in an anomalously bright outburst, and subsequent spectroscopic observations by multiple observers show clear signs of a classical nova. Observations of this anomalous event are requested immediately, and observers are asked to continue observing this object until it returns to its previous quiescent level.
The following observations were reported via CBET 2199, 2204, and 2205 (D.W.E. Green, editor; please see those issues of CBET for complete details):
V407 Cyg was discovered in a bright outburst on 2010 March 10.797 (JD 2455266.297) by K. Nishiyama (Fukuoka, Japan) and F. Kabashima (Saga, Japan) at an unfiltered magnitude of 7.4 obtained with a 105-mm camera lens. They then confirmed the observation using a 0.4-meter reflector, finding the object at an unfiltered magnitude of about 6.9. The object was independently discovered in outburst by the following observers: T. Kojima (Tsumagoi, Agatsuma-gun, Gunma-ken, Japan) at approximately magnitude 7 (measured at magnitude 7.3 by S. Nakano) on an image taken with a Canon EOS 40D camera on 2010 March 11.789 (JD 2455267.289); K. Sakaniwa (Higashichikumagun, Nagano, Japan) at magnitude 7.4 on images taken with a 70-mm Canon digital camera on 2010 March 11.8 (2455267.3); A. Tago (Tsuyama, Okayama-ken, Japan) at approximately 7th magnitude on images taken 2010 March 11.815 (2455267.315).
Subsequent spectroscopy by Munari et al on 2010 March 13.09 (JD 2455268.59) indicates a peculiar composite spectrum with evidence for a classical nova in progress, namely broad emission lines with FWHM of 2300 km/s. Such high velocities cannot occur in symbiotic stars, and so the current eruption appears to be a nova outburst in progress. Low resolution spectra also showing signs of a nova eruption were obtained by the following observers: K. Imamura (Okayama University of Science, Okayama, Japan) on 2010 March 13.793; M. Fujii (Okayama, Japan) on March 13.793; H. Maehara (Kwasan Observatory, Kyoto University, Kyoto, Japan) on March 13.842.
In summary, the evidence points to a classical nova eruption of a symbiotic star. The system is further complicated by the fact that the donor star in the system is likely a variable of Mira type. All observations of this complex and interesting system, including visual estimates, CCD time series, and multicolor photometry are strongly encouraged.
The following observations have been submitted to the AAVSO as of 2010 March 15.5 UT:
P. Schmeer, Saarbruecken-Bischmisheim, Germany, m(vis)=7.9 on 2010 March 12.184 (JD 2455267.684);
B. Granslo, Fjellhamar, Norway, m(vis)=8.5 on 2010 March 12.941 (2455268.441);
B. Granslo, m(vis)=8.8 on March 13.842 (2455269.342);
B. Granslo, m(vis)=8.6 on March 14.789 (2455270.289);
K. Geary, Kingscourt, Ireland, m(vis)=8.7 on March 14.8958 (2455270.3958); and
V. Voropaev, Krasnogorsk, Russia, m(vis)=9.2 on March 15.0129 (2455270.5129).
V407 Cyg is located at the following (J2000) coordinates: RA: 21 02 09.85 , Dec: +45 46 33.0
Please promptly submit all observations to the AAVSO using the name "V407 CYG".
Congratulations to K. Nishiyama, F. Kabashima, T. Kojima, K. Sakaniwa, and A. Tago for their discoveries!
This AAVSO Alert Notice was prepared by Dr. Matthew Templeton.