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 ...
of stars in the northern
circumpolar constellation
A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest p ...
of
Cepheus
Cepheus (Ancient Greek: Κηφεύς ''Kepheús'') may refer to:
In Greek mythology
* Cepheus (father of Andromeda), and King of Aethiopia
* Cepheus (son of Aleus), a king of Tegea, Arcadia
In astronomy
* Cepheus (constellation), one of the 88 m ...
, discovered by
Caroline Herschel
Caroline Lucretia Herschel ( , ; 16 March 1750 – 9 January 1848) was a German astronomer, whose most significant contributions to astronomy were the discoveries of several comets, including the periodic comet 35P/Herschel–Rigollet, which b ...
in 1787. The surrounding emission nebulosity is known colloquially as the Wizard Nebula, which spans an angle of . German-born astronomer
William Herschel
Frederick William Herschel ( ; ; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover ...
included his sister's discovery in his catalog, and labelled it H VIII.77. The nebula is known as S 142 in the 1959
Sharpless catalog
The Sharpless catalog is a list of 313 H II regions (emission nebulae) intended to be comprehensive north of declination −27°. (It does include some nebulae south of that declination as well.) The first edition was published in 1953 with 1 ...
(Sh2-142). It is extremely difficult to observe visually, usually requiring very dark skies and an O-III filter. The NGC 7380 complex is located at a distance of approximately from the
Sun
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...
, in the
Perseus Arm
The Perseus Arm is one of two major spiral arms of the Milky Way galaxy. The second major arm is called the Scutum–Centaurus Arm. The Perseus Arm begins from the distal end of the long Milky Way central bar. Previously thought to be 13,000 ligh ...
of the
Milky Way
The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...
.
The cluster spans ~ with an elongated shape and an extended tail. Age estimates range from 4 to 11.9 million years. At the center of the cluster lies
DH Cephei
DH Cephei is a variable binary star system in the northern circumpolar constellation of Cepheus (constellation), Cepheus, positioned about two degrees to the east of the star system Delta Cephei. With an apparent visual magnitude of 8 ...
, a close, double-lined
spectroscopic binary
A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...
system consisting of two massive
O-type star
An O-type star is a hot, blue star of spectral type O in the Yerkes classification system employed by astronomers. They have surface temperatures in excess of 30,000 kelvins (K). Stars of this type have strong absorption lines of ionised h ...
s. This pair are the primary ionizing source for the surrounding
H II region
An H II region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light year ...
, and are driving out the surrounding gas and dust while triggering star formation in the neighboring region. Of the
variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...
s that have been identified in the cluster, 14 have been identified as pre-main sequence stars while 17 are
main sequence star
Main may refer to:
Geography
*Main River (disambiguation), multiple rivers with the same name
*Ma'in, an ancient kingdom in modern-day Yemen
* Main, Iran, a village in Fars Province
* Spanish Main, the Caribbean coasts of mainland Spanish terri ...
s that are primarily B-type variables.
Gallery
File:SH2-142HunterWilson.jpg, NGC 7380 in Hubble Palette (Ha/OIII/SII)
File:The Wizard Nebula.jpg, NGC 7380 from WISE.
File:NGC7380 Nebula from the Mount Lemmon SkyCenter Schulman Telescope courtesy Adam Block.jpg, NGC 7380 from the Mount Lemmon SkyCenter using the 0.8m Schulman Telescope.Broadband (RGB) image.
File:NGC7380_Nebula_from_South_Common_Observatory_courtesy_Richie_Jarvis.jpg, NGC7380 Nebula from South Common Observatory