Astrophysics (Index)About

nova

(N)
(white dwarf explosion)

A nova (sometimes abbreviated/symbolized by N) is a white dwarf explosion less energetic than a supernova. It is a thermonuclear explosion (CNO cycle) of surrounding compressed hydrogen accreted from a binary companion. Novae appear as brighter stars that gradually lose their brightness, losing 2 magnitudes in 25 to 80 days, i.e., they may be faster or slower. The white dwarf survives and can produce another nova. Novae are regularly tracked in Andromeda and the Magellanic Clouds as well as the Milky Way.

The term classical nova (CN) is sometimes used to refer to the above case: the word nova basically means "new", and was coined for any apparently new stars in the sky, the above being the common underlying mechanism. (Nova is now often used for the star producing the transient and terms like nova eruption are used for the transients.) Aside from distinguishing it from supernovae and other less common cases, the term classical nova is sometimes used specifically to mean a one-time nova rather than a recurrent nova, i.e., a star that undergoes this brightening repeatedly. However, it is thought that classical novae are generally recurrent, the non-recurrent novae merely being highly infrequent: such a nova's recurrence rate can be once a year or can be once a gigayear.

Gamma rays have been detected in some recent classical novae, producing research interest, suggesting shock in surrounding material. Previous lack of detection is probably because gamma rays are blocked by Earth atmosphere, and the emissions are faint.

The term X-ray nova is used for something different: a type of X-ray transient ascribed to material falling into a black hole or neutron star, material from a companion star or perhaps a whole star.

Novae are sometimes identified with a nova-specific designator, "Nova" followed by the constellation name in Latin genitive form (as is used in a Bayer designation) followed by a year, optionally followed by a letter. An abbreviated form uses the letter "N" and the constellation abbreviation. Such designators for novas in other galaxies generally cite the galaxy rather than the constellation, e.g., Nova LMC 1968. Novae are also commonly designated by a variable star designation or other designation of the star.


(stars,event type,transient type)
Further reading:
https://en.wikipedia.org/wiki/Nova
https://en.wikipedia.org/wiki/X-ray_transient
https://astronomy.swin.edu.au/cosmos/N/Novae
https://astronomy.swin.edu.au/cosmos/C/Classical+Novae
http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/nova.html
https://scienceworld.wolfram.com/astronomy/Nova.html
https://www.aavso.org/vsots_novae
PrefixExample  
NN Her 2021abbreviated
NovaNova Herculis 2021 

Referenced by pages:
calcium-rich gap transient (ca-rich gap transient)
cataclysmic variable star (CV)
common envelope (CE)
cosmic dust
detonation
dwarf nova (DN)
Evryscope
GW170817
helium runaway
kilonova (KN)
luminous red nova (LRN)
MACHO Project
mass transfer
PHOENIX stellar model
POINT-AGAPE
rare designator prefixes
RS Ophiuchi (RS Oph)
supernova (SN)
supernova impostor
supernova progenitor
supernova remnant (SNR)
T Pyxidis (T Pyx)
transient (AT)
transient astronomy
Type Ia supernova
V339 Delphini (V339 Del)
variable star
variable star designation
X-ray binary (XRB)
X-ray burster (XRB)

Index