V1331 Cygni (also known as V1331 Cyg) is a

young star A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence. Earlier in its life, the object is a protostar that grows by acquiring mass from its surrounding envelope o ...

in the constellation Cygnus. V1331 Cyg is located in the

dark nebula A dark nebula or absorption nebula is a type of interstellar cloud, particularly molecular clouds, that is so dense that it obscures the visible wavelengths of light from objects behind it, such as background stars and emission or reflection ...

LDN 981. V1331 Cygni is most noted for having an arc-like reflection nebula surrounding it. This

circumstellar disc A Circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the rese ...

is a great birthplace for young stars, which form in the cloud. V1331 Cygni is heavily obscured by dust, so the properties of the central star are hard to deduce; however, it is estimated to have a radius five times that of the Sun and a mass of . V1331CygLightCurve

The

General Catalog of Variable Stars A general officer is an officer of high rank in the armies, and in some nations' air and space forces, marines or naval infantry. In some usages, the term "general officer" refers to a rank above colonel."general, adj. and n.". OED Online ...

classifies V1331 Cygni as an "INST" type variable, meaning a

T Tauri star T Tauri stars (TTS) are a class of variable stars that are less than about ten million years old. This class is named after the prototype, T Tauri, a young star in the Taurus Molecular Cloud, Taurus star-forming region. They are found near mo ...

which shows rapid light variations. Its visual band brightness varies from

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

13.08 to 10.58. It is sometimes classified as a pre- FUOR star. A semi-regular period of ~449 days has been reported. Unlike many T Tauri stars, the mean brightness of V1331 Cygni remains nearly constant over long time periods.

Gallery

File:V1331 Cygni Proto Nebula from the Mount Lemmon SkyCenter Schulman Telescope courtesy Adam Block.jpg, Dark nebula LDN 981 and V1331 Cygni (top center) by the Mount Lemmon SkyCenter

References

Variable stars Cygnus (constellation) Cygni, V1331 T Tauri stars {{Variable-star-stub