M31-RV is a possible red

cataclysmic variable star In astronomy, cataclysmic variable stars (CVs) are stars which irregularly increase in brightness by a large factor, then drop back down to a quiescent state. They were initially called novae (), since those with an outburst brightness visible t ...

located in the

Andromeda Galaxy The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a Galaxy#Isophotal diameter, D25 isop ...

(M31) that experienced an outburst in 1988, which was similar to the outburst

V838 Monocerotis V838 Monocerotis (Nova Monocerotis 2002) is a Cataclysmic variable star, cataclysmic binary star in the constellation Monoceros (constellation), Monoceros about 19,000 light years (6 parsec, kpc) from the Sun. The previously unremarked st ...

experienced in 2002. At peak brightness, M31-RV was the most luminous red supergiant in the

Local Group The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a " dumbbell" shape; the Milky Way ...

. Such objects have been called luminous red novae or intermediate-luminosity red transients. During the outburst, both V838 Mon and M31-RV reached a maximum absolute visual magnitude of -9.8. In 2006, the area around M31-RV was observed using the

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

, but only red giants were seen. Most likely the star either became too dim for Hubble to see, the star is a companion of one of the red giants, or the star is one of the red giants themselves. M31-RV reached a peak

visual magnitude Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...

of 17 before fading rapidly and showing dust formation. The most likely explanation states that these outbursts occur during

stellar merger A stellar collision is the coming together of two stars caused by stellar dynamics within a star cluster, or by the orbital decay of a binary star due to stellar mass loss or gravitational radiation, or by other mechanisms not yet well understo ...

events.

Notes

References

Andromeda (constellation) M-type supergiants Luminous red novae Stars in the Andromeda Galaxy Extragalactic stars {{var-star-stub

See also

Notes

References