Home > Star Clusters > Open > M45

M45

Messier 45
Pleiades (Seven Sisters)
Open Star Cluster
Right Ascension 03h 47m 0s Best Seen 12/15-3/15
Declination 24° 07' 00" Magnitude 1.6
Constellation Taurus

Actual		 Compared
to Sun
Distance 380 ly --
Diameter -- --
Number of Stars ~500 1
Actual Brightness -- --
Age 100 million years 5 billion
Integrated Spectral Type -- G2 V
Density (gram/cubic cm) -- --

What To Look For Through The Telescope

  1. Recommended eyepiece: 80 mm, using 6".

  2. When people look through the telescope the cluster will appear as a group of individual stars; all seven primary stars should be visible in the field of view.

M45 Information

  1. The Pleiades are among those objects which are known since pre-historical times. The first written record of the cluster dates to around 1000 B.C.

  2. The Pleiades is the most famous star cluster on the sky and can be seen without binoculars from even the depths of a light-polluted city. It is one of the brightest and closest open clusters.

  3. From the city, one can see six of the stars. With a clear, dark sky, the number jumps to 12.

  4. The cluster includes mostly faint stars, spread over a 2 degree field. (four times the diameter of the Moon.)

  5. This is a reflection nebulae, reflecting the light of the bright stars situated near or within them.

  6. The Pleiades have an expected future lifetime (as a cluster) of about 250 million years. After that, they will have been spread as individual (or multiple) stars along their orbital path.

  7. The Pleiades contain some white dwarf stars. These stars were once massive so that they evolved fast, but quickly lost the greatest part of their mass. Possibly they have lost another considerable percentage of their mass in the planetary nebula.

Other Pleiades information:

  1. The name "Pleiades" may be derived from either the Greek word for "to sail", or the word "pleios" meaning "full" or "many". The present author prefers the view that the name may be derived from the mythological mother, Pleione, which is also the name of one of the brighter stars.

  2. Their Japanese name is "Subaru", which was taken to christen the car of same name.

  3. The Persian name is "Soraya", after which the former Iranian empress was named.

  4. Old European (English and German) names indicate they were once compared to a "Hen with Chicks".

  5. On March 4, 1769, Charles Messier included the Pleiades as number 45 in his first list of nebulae and star clusters, published 1771.

  6. The names of the brightest stars:
Star Magnitude
Alcyone 2.90
Atlas 3.62
Electra 3.70
Maia 3.87
Merope 4.18
Taygeta 4.30
Celaeno 5.46
Asterope 5.80

  1. The Trumpler classification is given for the Pleiades as I, 3, r, n.

  2. The cluster also contains several brown dwarfs.
Home > Star Clusters > Open > M45 > Reference top
References
Item Updated Notes