NGC 4103 is an

open cluster An open cluster is a type of star cluster made of up 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, an ...

in the constellation

Crux Crux () is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name ''Crux'' is Latin for ...

. It was discovered by

James Dunlop James Dunlop FRSE (31 October 1793 – 22 September 1848) was a Scottish astronomer, noted for his work in Australia. He was employed by Sir Thomas Brisbane to work as astronomer's assistant at his private observatory, once located at Paramat ...

in 1826. It is located approximately 5,000 light years away from Earth, in the Carina-Sagittarius arm.

Characteristics

NGC 4103 is a young open cluster. Its age has been determined to be 30 Myr by Sagar & Cannon (1997), 20 ± 5 Myr by Sanner et al. (2001) and 6 Myr by Piskunov et al. (2004). The metallicity of NGC 4103 is subsolar (−0.47). The tidal radius of the cluster is 12.1 - 15.9 parsecs (39 - 51 light years) and represents the average outer limit of NGC 4103, beyond which a star is unlikely to remain gravitationally bound to the cluster core.

Members

There are 421 probable member stars within the angular radius of the cluster and 199 within the central part of the cluster. No

blue straggler A blue straggler is a main-sequence star in an open or globular cluster that is more luminous and bluer than stars at the main sequence turnoff point for the cluster. Blue stragglers were first discovered by Allan Sandage in 1953 while perform ...

has been detected in the cluster. The cluster is not very richly populated and is dominated by moderately bright stars of 10th magnitude and fainter. The hottest stars of the cluster are of spectral type B2. No red giants have been found to be members of the cluster. One member of the cluster is a

Be star Be stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as ''classical Be stars'', is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer e ...

. Among the members of the cluster is AI Crucis, a short-period semi-detached massive close binary star, with orbit period 1.41771 days. The orbital period of the binary is continuously increasing and this has been explained on the grounds of mass transfer from the less massive component to the more massive one and strong stellar wind from the hot component. It is estimated that 4.1 have been transferred from the hot component to the more massive.

References

External links

{{DEFAULTSORT:NGC 4103 4103 Crux Open clusters