Object Information:

In astronomy, the Pleiades, or Seven Sisters (Messier 45 or M45), is an open star clustercontaining middle-aged, hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky. The celestial entity has several meanings in different cultures and traditions.

The cluster core radius is about 8 light years and tidal radius is about 43 light years. The cluster contains over 1,000 statistically confirmed members, although this figure excludes unresolved binary stars. It is dominated by young, hot blue stars, up to 14 of which can be seen with the naked eye depending on local observing conditions. The arrangement of the brightest stars is somewhat similar to Ursa Major and Ursa Minor. The total mass contained in the cluster is estimated to be about 800 solar masses.

The cluster contains many brown dwarfs, which are objects with less than about 8% of the Sun's mass, not heavy enough fornuclear fusion reactions to start in their cores and become proper stars. They may constitute up to 25% of the total population of the cluster, although they contribute less than 2% of the total mass. Astronomers have made great efforts to find and analyse brown dwarfs in the Pleiades and other young clusters, because they are still relatively bright and observable, while brown dwarfs in older clusters have faded and are much more difficult to study.


More information here.

Exposure Information:

1h30 minutes exposure

Lights: 18x300" 1600ISO
Darks: 8
Flats: 30
Bias: 50

Temperature 10ºC
Moon phase 1%

Note: low exposure image taken while waiting for M81 and M82

Imaged at: Prades, Tarragona, CATALUNYA - SPAIN

Optics - GSO- 200/1000 Newtonian f/5
Camera - Canon 450D moded (IR filter removed)
Mount - Sky-Watcher Neq6 PROII
Guiding scope – EZG 60/230
Guiding and planetary camera – ASI 174MC

Software: APT, PHD2, DSS, PIX

Image date: December 30th, 2016