V842 Centauri, also known as Nova Centauri 1986, 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 ...

which occurred in 1986 in the constellation Centaurus. It was discovered by

Robert H. McNaught Robert H. McNaught (born in Scotland in 1956) is a Scottish-Australian astronomer at the Research School of Astronomy and Astrophysics of the Australian National University (ANU). He has collaborated with David J. Asher of the Armagh Observator ...

Siding Spring Observatory Siding Spring Observatory near Coonabarabran, New South Wales, Australia, part of the Research School of Astronomy & Astrophysics (RSAA) at the Australian National University (ANU), incorporates the Anglo-Australian Telescope along with a coll ...

in Australia, on 22 November 1986. At the time of its discovery, it had an apparent magnitude of 5.6. It reached a peak magnitude of 4.6 one and a half days later, making it easily visible to the naked eye. V842 Centauri is considered a moderately fast nova, having faded by 3 magnitudes after 48 days. Near the end of 1986, and early in 1987, its light curve showed a sharp drop in brightness, caused by the formation of dust. This dramatic fading lasted only about 50 days, before the nova brightened by about 2.5 magnitudes. By 2010, it had faded to magnitude 16.5, but was still 2 magnitudes brighter than before the nova eruption. From its shell's expansion velocity, it is estimated to be at a distance of 1.5 kpc (4900 light-years) from Earth. Another method, based on the system's extinction rate, gives a similar distance of 1.65 ± 0.54 kpc. It was observed by the Gaia spacecraft, which measured a distance of 1.38 (+0.120, -0.078) kpc. The mass of the white dwarf in V842 Centauri is estimated at 0.88

solar mass The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

es. The system is likely seem from a low inclination. An expanding

nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...

has been detected around V842 Centauri, formed by material ejected during the nova. It has two components, with diameters of 3.6" and 10.6", corresponding to material with different densities and expansion velocities. A 2009 photometric study of V842 Centauri found a possible 57 seconds period in the system's light curve, which was interpreted as the white dwarf's rotation period. An orbital period of 3.94 hours was calculated from variations of this period. V842 Centauri was then classified as an

intermediate polar In astronomy, an intermediate polar (also called a DQ Herculis Star) is a type of cataclysmic variable, binary star system with a white dwarf and a cool main-sequence secondary star. In most cataclysmic variables, matter from the companion sta ...

, with the third fastest rotation period for a cataclismic system. However, two later studies revealed problems with this classification. In 1995, observations with the 3.9 meter

Anglo-Australian Telescope The Anglo-Australian Telescope (AAT) is a 3.9-metre equatorially mounted telescope operated by the Australian Astronomical Observatory and situated at the Siding Spring Observatory, Australia, at an altitude of a little over 1,100 m. In 20 ...

detected a very small (~1.5 arc second diameter) nova remnant shell surrounding V842 Centauri. By March 1998 the shell had expanded to 5.6 × 6.0 arc seconds.

References

External links

V842 Centauri

V 842 Cen
* https://web.archive.org/web/20050907140444/http://www.tsm.toyama.toyama.jp/curators/aroom/var/nova/1980.htm {{DEFAULTSORT:V842 Centauri Novae Centaurus Astronomical objects discovered in 1986 Centauri, V842 Discoveries by Robert H. McNaught