Unraveling the oldest and faintest recovered nova : CK Vulpeculae (1670).

A narrow band H-alpha + forbidden N II CCD image of the field of Nova CK Vul (1670) was analyzed in comparison with the light curve derived from old European records. The CCD image was obtained using the Multiple Mirror Telescope at Cerro Tololo International Observatory. The image shows a ring inside the field of CK Vul having several bright subcondensations and a central star. A net H-alpha tube plate image taken with the 3.6 m Canada-France-Hawaii Telescope shows a faint jet leading to an H-alpha bright knot. It is hypothesized that the jet was caused by polar ejections. Constraints established on the distance of CK Vul place it at 550 + or - 150 pc from the sun. The implied nebular expansion velocity is 59 + or - 16 km/s. The absolute magnitude of CK Vul is estimated to be about 10.4 mag, about 6 mag fainter than canonical old novae. On the basis of the observations of CK Vul, it is suggested that published survey-based values for the space density and lifetimes of cataclysmic binaries may be underestimated.