A stellar association is a very loose star cluster, looser than both open clusters and globular clusters. Stellar associations will normally contain from 10 to 100 or more visible stars. An association is primarily identified by commonalities in its member stars' movement vectors, ages, and chemical compositions. These shared features indicate that the members share a common origin. Nevertheless, they have become gravitationally unbound, unlike star clusters, and the member stars will drift apart over millions of years, becoming a moving group as they scatter throughout their neighborhood within the galaxy.
Cepheus is a constellation in the deep northern sky, named after Cepheus, a king of Aethiopia in Greek mythology. It is one of the 48 constellations listed by the second century astronomer Ptolemy, and it remains one of the 88 constellations in the modern times.
V354 Cephei is a red supergiant star located within the Milky Way. It is an irregular variable located over 13,000 light-years away from the Sun. It has an estimated radius of 1,139 solar radii. If it were placed in the center of the Solar System, it would extend to between the orbits of Mars and Jupiter.
HD 93129 is a triple star system in the Carina Nebula, with all three components being hot O class stars amongst the most luminous stars in the Milky Way. It is the dominant member of the Trumpler 14 star cluster, a young star cluster within the Carina OB1 stellar association that harbors other super-luminous stars, like Eta Carinae and WR 25.
Nu Cephei is a class A2, fourth-magnitude blue supergiant star in the constellation Cepheus. It is a white pulsating α Cygni variable star located about 4,700 light-years from Earth.
W Cephei is a spectroscopic binary and variable star located in the constellation Cepheus. It is thought to be a member of the Cep OB1 stellar association at about 8,000 light years. The supergiant primary star is one of the largest known stars and as well as one of the most luminous red supergiants.
19 Cephei is a supergiant star in the northern circumpolar constellation of Cepheus. It has a spectral class of O9 and is a member of Cep OB2, an OB association of massive stars located about 615 parsecs (2,010 ly) from the Sun.
Kappa Crucis is a spectroscopic binary star in the open cluster NGC 4755, which is also known as the Kappa Crucis Cluster or Jewel Box Cluster.
RW Cephei is a K-type hypergiant and a semirregular variable star in the constellation Cepheus, at the edge of the Sharpless 132 H II region and close to the small open cluster Berkeley 94. It is among the largest stars known with a radius of almost 1,000 times that of the Sun (R☉), nearly as large as the orbit of Jupiter.
HD 165516 is a blue supergiant star in the constellation Sagittarius. It is part of the Sagittarius OB1 association and appears against a rich Milky Way starfield near the Triffid Nebula and Lagoon Nebula.
9 Cephei, also known as V337 Cephei, is a variable star in the constellation Cepheus.
Trumpler 16 is a massive open cluster that is home to some of the most luminous stars in the Milky Way galaxy. It is situated within the Carina Nebula complex in the Carina–Sagittarius Arm, located approximately 9,270 ly (2,842 pc) from Earth. The cluster has one star visible to the naked eye from the tropics southward, Eta Carinae.
Carina OB1 is a giant OB association in the Carina Nebula, which is home to some of the most massive and luminous stars in the Milky Way Galaxy. It includes the young star clusters Collinder 228, NGC 3293, NGC 3324, IC 2581, Trumpler 14, Trumpler 15 and Trumpler 16, the last being the home of Eta Carinae. It also includes another massive and luminous star, HD 93129A. It is approximately 2,680 parsecs (8,700 ly) from Earth.
Perseus OB1 is an OB association in the Northern Celestial Hemisphere in the constellation Perseus. It is centered around the double cluster, and has lent its name to the Perseus Arm of the Milky Way. The brightest member of the association is the blue supergiant 9 Persei.
NGC 654 is an open cluster in the constellation Cassiopeia. It was discovered by William Herschel in 1787. With apparent magnitude 6.5, it can be observed by binoculars. It is located 2,5° northeast of the star Delta Cassiopeiae. In the same low power field can also be seen the open clusters NGC 663 and NGC 659. It surrounds a 7th magnitude yellowish star, an F5Ia supergiant, which is a possible member of the group.
U Lacertae is a spectroscopic binary star in the constellation Lacerta.
HD 143183 is a red supergiant variable star of spectral type M3Ia in constellation Norma. It is a member of the Norma OB1 association, at a distance of about 2 kiloparsecs. It is one of the most luminous red supergiants with a luminosity over 100,000 times greater than the Sun (L☉), and is as well one of the largest stars with a radius more than a thousand times that of the Sun (R☉). Older studies frequently calculated higher luminosities and radii. It has an estimated mass loss rate of 5×10−5 M☉ per year and has been once described as a cool hypergiant. It is surrounded by a dozen early-type stars and a circumstellar nebula which extends 0.12 parsecs (0.39 ly).
Pismis 20 is a compact open cluster in Circinus. It is located at the heart of the Circinus OB1 association in the Norma arm of the Milky Way Galaxy. Pismis 20 is about 3,270 pc away and only about 5 million years old. HD 134959, a blue supergiant variable star also called CX Circinus, is the brightest star in Pismis 20.
Camelopardalis OB1 is a group of young stars that share a common origin and a similar motion through space, but, as a whole, are no longer gravitationally bound. The name indicates this stellar association is located in the area of the Camelopardalis constellation which includes a number of massive, short-lived OB stars. The association is ~3,300 ly (1,000 pc) distant from the Sun, with members lying between 500 pc and 1,500 pc away. It is located on the edge of the local Orion Arm of the Milky Way galaxy and lies outside the traditional Gould Belt.
HD 151804, also known as HR 6245 and V973 Scorpii, is a blue supergiant star about 7000 light years from the Earth, in the constellation Scorpius. It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer far from city lights. It is a variable star, whose brightness varies slightly from magnitude 5.22 to 5.28, on time scales of a few days. It is one of the brightest stars in the Scorpius OB1 association, and is located half a degree from NGC 6231, which is part of the same association.
