Collinder 135, known sometimes as the Pi Puppis Cluster, is an

open cluster An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

Puppis Puppis ("poop deck, stern") is a constellation in the southern sky. It was originally part of the Former constellations, traditional constellation of Argo Navis (the ship of Jason and the Argonauts), which was divided into three parts, the other ...

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

. It consists of six stars brighter than 6th magnitude, and a widespread population of fainter stars. It lies in the southern

celestial hemisphere In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, ...

near a rich star field. The main component is the star

Pi Puppis Pi Puppis, Latinisation of names, Latinized from π Puppis, also named Ahadi, is the List of stars in Puppis, second-brightest star in the southern constellation of Puppis. It has an apparent visual magnitude of about 2.7, so it ...

, which gives to the cluster its common name; it is an orange supergiant with a

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 2.71. Two of the 5th magnitude stars are all

variables Variable may refer to: Computer science * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed Mathematics * Variable (mathematics), a symbol that represents a quantity in a mathemat ...

NV Puppis NV Puppis (NV Pup), also known as υ1 Puppis, is a class B2V (blue main-sequence) star in the constellation Puppis. Its apparent magnitude is 4.67 and it is approximately 800 light years away based on parallax. It is a γ Cas variable, ...

is a

Gamma Cassiopeiae variable A Gamma Cassiopeiae variable (γ Cassiopeiae variable) is a type of variable star, named for its prototype γ Cassiopeiae. Variability γ Cassiopeiae variables show irregular changes in brightness on a timescale of decades. These typically ha ...

, while NW Puppis is a

Beta Cephei variable Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200 ...

References

External links

*{{commonscat-inline
Observing Cr 135
Open clusters Puppis