V407 CYGNI in Outburst

According to Cbet No.2199 issued on March 11, 2010, the symbiotic star V407 Cyg is undergoing an apparent unusually bright outburst (mag 7.4). The outburst has been detected by Koichi Nishiyama (Fukuoka, Japan) and Fujio Kabashima (Saga, Japan) by means an unfiltered CCD image taken on Mar. 10.797 UT using a105-mm camera lens + CCD. (independent discovery of this outburst by Tadashi Kojima).

We performed some follow-up of this outburst, remotely with a 0.25-m, f/4.3 reflector + CCD + Johnson V and Cousins R filters. On 2010 March 12.45, we measured Vj= 8.2 and Rc= 7.2 (accuracy about 0.1 magnitude in each band).

Coordinates extracted by our images:

R.A. = 21h 02m 09s.82, Decl. = +45d 46' 33".0
(equinox 2000.0, reference catalogue USNO-B1)

Our image. Click on it for a bigger version:

Here you can see a gif animation showing a comparison between one of our images of V407 Cyg Outburst and an archive DSS plate. Our image is a 60sec exposure, unfiltered obtained on March 12, 2010. The DSS is an image of 11 September 1990 (R Filter).

The usual V407 Cyg observed range is magnitude 13 to fainter than 17; it may have been a slow nova in 1936, and a Mira-type variable appears involved with this object, as well. This brightening is well outside its previously stated range and may indicate a nova outburst in progress.

According to the AAVSO: "Suggested classifications for this source include slow nova with either a Mira secondary or Mira component, or a symbiotic star. Spectroscopy and multicolor photometry may provide more information on the nature of this system, while visual observations and time-series photometry will be needed for tracking the overall light evolution of the system"

Spectroscopic observations are urgently required.

UPDATE - March, 14

Spectra indicates that the object is indeed undergoing a nova outburst, in a symbiotic environment!! A scenario reminiscent of the symbiotic recurrent nova RS Oph.

According to Cbet 2204, U. Munari et al. (INAF-ANS coolaboration) report that they obtained absolutely fluxed, low-resolution spectra of V407 Cyg. The spectral appearance is a highly peculiar one. The spectrum is completely different from those ever recorded for this object and other symbiotic Mira variables in outburst. The white dwarf companion to the Mira variable is experiencing an outburst similar to that of classical novae, and its ejecta are moving in the circumstellar environment already filled by the ionized wind of the Mira.

Imamura-san's spectrum (Okayama U. of Sci.) :

by Ernesto Guido & Giovanni Sostero