Host galaxies of novae discovered in 2018 The following is a list of all novae that are known to have occurred in 2018. A nova is an energetic astronomical event caused by a white dwarf accreting matter from a star it is orbiting (typically a red giant, whose outer layers are more weakly attached than smaller, denser stars) Alternatively, novae can rarely be caused by a pair of stars merging with each other, however such events are vastly less common than novae caused by white dwarfs.
In 2018, 15 novae were discovered in the Milky Way, 14 being classical novae, and 1 being a dwarf nova of a previously known variable star, V392 Persei, which was discovered in 1972. An additional 23 novae were discovered in the Andromeda Galaxy, 8 in Messier 81, 1 in the Triangulum Galaxy, and 1 in Messier 83. A single luminous red nova was observed in NGC 45.
List of novae in 2018 In the Milky Way Nova nameDiscovery dateConstellationRight ascensionDeclinationPeakbrightness (v)Distance(light-years)Absolutemagnitude (v)Nova typeOrigin systemidentified?Companion starspectral typeIn most cases, the spectral type is estimated based on the absolute magnitudeV357 Muscae2018/01/14Musca6.5ClassicalYesF9V/G0VV1661 Scorpii2018/01/17Scorpius10.2??ClassicalYes?FM Circini2018/01/19Circinus5.9ClassicalYesG1VV1662 Scorpii2018/02/06Scorpius10.1??ClassicalYes?V3664 Ophiuchi2018/02/12Ophiuchus12.5ClassicalYesM0II/IIIV1663 Scorpii2018/02/24Scorpius12.3ClassicalMaybe?V3665 Ophiuchi2018/03/10Ophiuchus9.4??ClassicalYes?V906 Carinae2018/03/20Carina5.9ClassicalYes?V435 Canis Majoris2018/03/24Canis Major12.0??ClassicalMaybe?V5857 Sagittarii2018/04/08Sagittarius10.8??ClassicalYes?V392 Per2018/04/29Perseus6.3??dwarf nova & novaYes?V408 Lupi2018/06/03Lupus9.0ClassicalMaybeK7V?V613 Scuti2018/06/29Scutum10.3??ClassicalYes?V3666 Ophiuchi2018/08/08Ophiuchus9.0??ClassicalNo?V556 Normae2018/10/13Norma10.2??ClassicalYes?
In the Andromeda Galaxy Novae are also frequently spotted in the Andromeda Galaxy, and are even slightly more commonly found than in the Milky Way, as there is less intervening dust to prevent their detection. Furthermore, Andromeda is circumpolar for observers north of latitude +48-50, roughly the latitude of the Canadian-American border, allowing observers north of that to search for transients all year.
In 2018, 23 novae were seen in the Andromeda galaxy. Nova nameDiscovery dateRight ascensionDeclinationPeakbrightness (v)Absolutemagnitude (v)PNV J00444425+41424492018/01/1018.4 -6.1PNV J00431577+41183932018/01/1217.8 -6.7PNV J00423439+40442552018/02/0716.7 -7.8PNV J00415059+41254992018/02/2217.9 -6.6PNV J00424041+41125222018/03/2118.1 -6.4PNV J00425509+41190092018/04/0317.6 -6.9PNV J00421895+41135242018/04/1916.9 -7.6PNV J00415353+41141212018/04/2917.5 -7.0PNV J00434212+41223492018/05/1917.0 -7.5PNV J00424144+41173772018/06/2617.1 -7.4PNV J00414889+41091482018/07/0117.4 -7.1PNV J00420765+41194382018/07/1217.3 -7.2PNV J00425261+41184092018/07/1518.6 -5.9PNV J00425074+41154612018/07/3119.1 -5.4PNV J00424214+41144572018/08/0217.5 -7.0PNV J00392190+40154882018/08/1319.0 -5.5PNV J00451587+42102692018/08/2117.9 -6.6PNV J00424990+41233482018/10/1117.9 -6.6PNV J00424012+41172732018/10/1317.5 -7.0TCP J00420310+41023312018/10/1518.0 -6.5PNV J00424065+41110802018/12/0318.7 -5.8PNV J00424241+41194112018/12/1718.2 -6.3PNV J00432462+41202222018/12/2218.0 -6.5PNV J00424380+41172082018/12/2317.5 -7.0
In other galaxies Any galaxy within 20 million light-years of the Sun could theoretically have nova events bright enough to be detected from Earth, although in practice most are only detected in galaxies within 10-15 million light-years of the Milky Way, such as the Triangulum Galaxy, Messier 81, Messier 82, Messier 83, and Messier 94.
In 2018, of the ten novae observed in other galaxies than the Milky Way or the Andromeda Galaxy, eight were in Messier 81, with the remaining two from the Triangulum Galaxy and Messier 83. A luminous red nova, probably caused by the merger of two stars, occurred in NGC 45. Nova nameDiscovery dateHost galaxyRight ascensionDeclinationPeakbrightness (v)Distance(million light-years)Absolutemagnitude (v)TypePNV J13370978-29565762018/01/28Messier 8320.715.2 -7.6 ClassicalPNV J09555926+69035172018/01/30Messier 8120.311.5 -7.4 ClassicalPNV J09545236+69040852018/02/19Messier 8120.011.5 -7.7 ClassicalPNV J09553607+69021412018/03/06Messier 8120.811.5 -6.9 ClassicalPNV J09551340+69004782018/03/20Messier 8121.211.5 -6.5 ClassicalPNV J09553194+69091472018/04/02Messier 8120.411.5 -7.3 ClassicalPNV J09555269+68584092018/04/09Messier 8120.611.5 -7.1 ClassicalAT 2018bwo2018/05/22NGC 45 16.4 32.6 -13.6 Luminous Red NovaPNV J09560988+68591082018/10/12Messier 8120.111.5 -7.6 ClassicalPNV J01334673+30321812018/10/13Triangulum Galaxy18.12.65 -6.4 ClassicalPNV J09555246+6902009 2018/11/06Messier 8120.011.5 -7.7 Classical
See also List of novae in the Milky Way galaxy List of novae in 2019 Nova Dwarf nova Luminous red nova Guest star (astronomy) Supernova
Notes
References
External links List of all galactic novae