Displaying items by tag: Open Cluster

Sunday, 24 April 2022 12:33

Trio of Messier Open Clusters

One classification of open clusters is the Trumpler classification. It consists of 3 parameters, the first is the degree of concentration.

I - Detached clusters with strong central concentration.
II - Detached clusters with little central concentration.
III - Detached cluster with no noticeable concentration.
IV - Clusters not well detached, but has a strong field concentration.

The second parameter is the range of brightness.

1 - Most of the cluster stars are nearly the same apparent brightness.
2 - A medium range of brightness between the stars in the cluster.
3 - Cluster is composed of bright and faint stars.

The last parameter categorizes the number of stars in the cluster.

p - Poor clusters with less than 50 stars.
m - Medium rich cluster with 50-100 stars.
r - Rich clusters with over 100 stars.

If the cluster any type of nebulosity, the letter "n" is added to the last parameter.


First up is Messier 34, located in the constellation of Perseus. Consisting of over 100 stars, in a space of a diameter of 14 light years. It is some 1,500 light years distance and shines at an apparent magnitude of 5.5 at an estimated age of 200 million years.

Published in Open Clusters
Friday, 24 December 2021 13:10

Messier 41 - (2021)

Messier 41 is an open cluster located in Canis Major near Sirius. The cluster contains some 100 members in a diameter of 25 light years. Estimated age of the cluster is around 200 million years. It is expected to remain as a cluster for 500 million years before dispersing. Brightest of the stars is an orange giant near the cent of the cluster. K3 type star, it has a magnitude of 6.3 and is 700 times more luminous than our Sun.

Published in Open Clusters
Wednesday, 22 December 2021 15:37

Messier 45 (2021)

Messier 45, one of the more famous open clusters. Often called the Pleiades or the Seven Sisters, with the name Pleiades coming from Greek mythology. The cluster has been known since ancient times, and can be seen as a grouping of 6-7 stars, so it was interesting that Charles Messier included it in his catalog of objects that are not a comet, but could be mistaken for one.

The cluster is surrounded by a reflection nebula that the group is currently passing through, and not related to its original birth in a compact nebula. The cluster consist of at least 1,000 stars located in a radius of 8 light years. The cluster is dominated by hot blue luminous stars, but also contains many brown dwarfs that are not massive enough to initiate nuclear fusion. The estimated age of the cluster is around 100 million years, and its expected to take 250 million years to disperse due to gravitational interactions.

Also a bright knot was discovered around Merope by astronomer Edward Barnard that is being eaten away by the intense radiation from Merope. Due to the dazzling light from Merope, it is difficult to see, and later given the designation of IC 349, or is sometimes referred to as Barnard's Merope Nebula or Merope's Companion.


Published in Open Clusters
Friday, 10 December 2021 17:06

NGC 457 - Owl Cluster

NGC 457 is an open cluster located in Cassiopeia, often called the Owl cluster, or a more recently the E.T. cluster with the two brightest stars forming eyes. I tend to see it more as an Owl. The cluster contains some 150 members and has an estimated age of around 21 million years. Less than idea weather for imaging, with a thin cirrus clouds, but a good bright target for commissioning the RC 10 scope and the ZWO 2600 mono camera.

Published in Open Clusters
Tuesday, 30 November 2021 17:12

NGC 7790 and NGC 7788

NGC 7790, center of image is a young open cluster located in Cassiopeia with an estimated age of 60 to 80 million years. Open cluster NGC 7788 lies to the lower left of NGC 7790

Published in Open Clusters
Friday, 26 November 2021 16:25

Messier 103 (2021)

Messier 103 is an ope star cluster located in Cassiopeia. Contains at least 107 members, its one of the smallest and at 10,000 light years one of the more remote clusters.

Published in Open Clusters
Friday, 05 March 2021 13:54

NGC 2129

A small compact open cluster. Consisting of 37 likely members, within a radius of 4 light years. Estimated age is around 10 million years making it a young cluster. 

Published in Open Clusters
Thursday, 21 January 2021 17:17

Messier 35

Messier 35, and NGC 2158, two open clusters located in Gemini the Twins. These are more like distant relatives. M 35 is relatively near by at only 2,800 light years, and NGC 2158 is a distant 15,000 light years away. M 35 is a young cluster at around 150 million years old, and NGC 2158 is an old 2 billion years old cluster. M 35 has an abundance of bright blueish stars that burn through their fuel at a faster rate, and only the older more yellowish survive in NGC 2158.

Published in Open Clusters
Friday, 15 January 2021 16:28

NGC 7510

NGC 7510 a compressed young open cluster located in Cepheus. Some dimming of the stars due to a plume of gas and dust that is plentiful in the area.

Published in Open Clusters
Wednesday, 30 December 2020 14:47

NGC 7209

NGC 7209 is an open cluster located in Lacerta, it consists of around 150 members with an estimated age of 420 million years. Discovers by William Herschel in October 1787.

Published in Open Clusters
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