Nova Cygni 1975 (center), photographed at 07:00 UT August 30, 1975. Also shown are 59 Cygni (magnitude 4.8), 60 Cygni (magnitude 5.4) and 63 Cygni (magnitude 4.5)
V1500 Cygni orNova Cygni 1975 was a brightnova occurring in 1975 in theconstellationCygnus. It had the second highest intrinsic brightness of any nova of the 20th century, exceeded only byCP Puppis in 1942.[10]V1500 Cygni was firstly reported byMinoru Honda of Kurashiki, Japan at 13h40m, 29 August 1975 (UT), shining at anapparent brightness of magnitude 3.0.[11] But the first discoverer in time was Kentaro Osada (August 29, 11h30m UT).[12]It had brightened to magnitude 1.7 on the next day, and then rapidly faded. It remained visible to the naked eye for about a week, and 680 days after reaching maximum the star had dimmed by 12.5 magnitudes.
The location of V1500 Cygni (circled in red)
It is anAM Herculis type star, consisting of ared dwarf secondary depositing a stream of material onto a highly magnetizedwhite dwarf primary. The distance of the V1500 Cygni was calculated in 1977 by theMcDonald Observatory at 1.95kiloparsecs (6,360 light years).[13] More recently theGaia space observatory determined a distance of approximately 5,100 light years.[1] Additionally, V1500 Cyg was the firstasynchronous polar to be discovered. This distinction refers to the fact that the white dwarf's spin period is slightly different from the binary orbital period.[14] However, by 2016, x-ray observations strongly suggested that the white dwarf rotation had returned to normal synchronization with the orbit.[4]
V1500 Cygni has aremnant typical of very fast novae, consisting of some clumps and some spherically symmetric diffuse material.[15]
^abSamus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)".VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S.1: B/gcvs.Bibcode:2009yCat....102025S.
^Sanyal, A. (1976). "Spectroscopic studies of nova Cygni 1975 during early decline".Publications of the Astronomical Society of the Pacific.88: 741.Bibcode:1976PASP...88..741S.doi:10.1086/130019.
^Ferland, G. J. (1977). "The interstellar reddening and distance of Nova Cygni 1975 /V1500 Cygni/".Astrophysical Journal.215: 873.Bibcode:1977ApJ...215..873F.doi:10.1086/155424.
^Stockman, H. S.; Schmidt, Gary D.; Lamb, D. Q. (1988). "V1500 Cygni - Discovery of a magnetic nova".The Astrophysical Journal.332: 282.Bibcode:1988ApJ...332..282S.doi:10.1086/166652.
