V1974 Cygni or Nova Cygni 1992 was a

nova A nova (plural novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramati ...

, visible to the naked eye, in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Cygnus. It was discovered visually with 10×50 binoculars on February 19, 1992, by Peter Collins, an amateur astronomer living in

Boulder, Colorado Boulder is a home rule city that is the county seat and most populous municipality of Boulder County, Colorado, United States. The city population was 108,250 at the 2020 United States census, making it the 12th most populous city in Color ...

. At that time he first noticed it, it had an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of 7.2. Nine hours later he saw it again, and it had brightened by a full magnitude. For this discovery Collins was awarded the AAVSO Nova Award in 1993. The nova reached magnitude 4.4 at 22:00 UT on 22 February 1992. Images from the

Palomar Sky Survey Palomar may refer to: Places * Any of several locations in San Diego County, California: ** Palomar Mountain ** Palomar Observatory, located on Palomar Mountain ** Palomar College in San Marcos, California ** Palomar Medical Center in Escondido, ...

taken before the nova event showed identified a possible precursor which had

photographic magnitude Photographic magnitude ( or ) is a measure of the relative brightness of a star or other astronomical object as imaged on a photographic film emulsion with a camera attached to a telescope. An object's apparent photographic magnitude depends on i ...

s of 18 (blue light) and 17 (red light), but the identification of the precursor is not firm. V1974 Cygni declined from peak brightness by three magnitudes in 43 days, making it a "fast" nova. Its light curve is classified as type P (Plateau), and it may be a

recurrent nova A nova (plural novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramati ...

. In 1995, V1974 Cygni was observed with the

Very Large Array The Karl G. Jansky Very Large Array (VLA) is a centimeter-wavelength radio astronomy observatory located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~ west of Socorro. The VLA comprises twen ...

at 1.49, 4.9, 8.4, 14.9 and 22.5 GHz. It was also studied with the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

instrument the

High Speed Photometer The High Speed Photometer (HSP) is a scientific instrument formerly installed on the Hubble Space Telescope. The HSP was designed to measure the brightness and polarity of rapidly varying celestial objects. It could observe in ultraviolet, visible ...

. The instrument recorded a short amount of ultraviolet photometry. The nova was also observed in the far-ultraviolet by

Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, ''Voyager 1'', on a ...

. It was observed, but not detected, with the

Compton Gamma Ray Observatory The Compton Gamma Ray Observatory (CGRO) was a space observatory detecting photons with energies from 20 k eV to 30 GeV, in Earth orbit from 1991 to 2000. The observatory featured four main telescopes in one spacecraft, covering X-ra ...

. It was the first nova to be observed throughout the electromagnetic spectrum, from radio waves to γ-rays. V1974CygLocation

All novae are binary stars, with a "donor" star orbiting a

white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes fro ...

. The two stars are so close to each other that matter is transferred from the donor to the white dwarf. In the case of V1974 Cygni, the binary's orbital period is 1 hour, 57 minutes. The nova has an oxygen-neon-magnesium white dwarf primary, making it a neon nova. Estimates of the mass of the white dwarf range from 0.98 to 1.12, and it is estimated to be acquiring of material from the donor star. V1974 Cygni has a

nova remnant A nova remnant is made up of the material either left behind by a sudden explosive fusion eruption by classical novae, or from multiple ejections by recurrent novae. Over their short lifetimes, nova shells show expansion velocities of around 1000& ...

shell which has been observed several times with the

, as well as with the

Infrared Space Observatory The Infrared Space Observatory (ISO) was a space telescope for infrared light designed and operated by the European Space Agency (ESA), in cooperation with ISAS (now part of JAXA) and NASA. The ISO was designed to study infrared light at wavelengt ...

. The shell is nearly circular, and its radius as of 10 February 1998 was 0.983 arc seconds. It is expanding at a rate of about 0.26 milli arc seconds per day. The remnant was also imaged in 6 cm radio waves with the

MERLIN Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and le ...

interferometer.

References

External links

* https://web.archive.org/web/20050915104557/http://www.tsm.toyama.toyama.jp/curators/aroom/var/nova/1990.htm * http://www.aavso.org/v1974-cyg-nova-cygni-1992 {{Novae Cygni, V1974 Novae Cygnus (constellation) 1992 in science

See also

References

External links