Star clusters

Messier 12

Messier 12, a globular star cluster
Messier 12 is a globular star cluster located about 20000 light years away towards the constellation of Ophiuchus. It is in a crowded region of the sky. It is easily found in a dark sky using even a small telescope.
(michael allen)

Messier 21

Open star cluster Messier 21.
Open star cluster Messier 21 is located about 4000 light years away towards the direction of Sagittarius. The brightest star, HD 164863, shines at 7th magnitude, the next few brightest at 9th. These are B-type stars, indicative of a young cluster.
(michael allen)

Messier 26

Open cluster Messier 26.
Open cluster Messier 26 lies in the direction of Scutum, towards the center of the Milky Way. It is about 5000 light years away. It is small and comparatively underpopulated with stars. The bright blue star at lower center shines at 9th magnitude; it is a rare B-type supergiant, a highly-evolved star near the end of its life. The red star just left of center is BD-09 4823, a spectroscopic binary with an orbital period of about 10.6 years. The pair shine with a combined 10th magnitude.
(michael allen)

Messier 92

Globular cluster Messier 92.
Globular cluster Messier 92 is located towards the constellation of Hercules. Its distance is quite uncertain, with estimates ranging from 26000 to 58000 light years, although its high apparent brightness favors the closer values. The brightest red stars in this image are red giants shining with 13th or 14th magnitude. The bright white star at lower left is an 11th magnitude star probably located about 15000 light years away, i.e., between us and the cluster.
(michael allen)

Messier 52

The open star cluster Messier 52.
Open star cluster Messier 52 lies about 5000 light years away in the direction of Cassiopeia. Its brightest star (middle left) is BD+60 2532, a F type supergiant which shines at 8th magnitude. At about 1000 stars its membership is quite rich. It has a modest age of about 150 million years.
(michael allen)

Messier 29

Open star cluster Messier 29.
Open star cluster Messier 29 is located towards Cygnus, a very busy region of the sky featuring lots of star clusters and nebulosity. Its brightest stars shine at 8th magnitude. It has a few dozen member stars, and at an age of 13 million years is quite young. The very bright star located almost exactly in the center of the image is a rare O-type star; it will end its life in a supernova explosion.
(michael allen)

Messier 93

Open cluster Messier 93.
Open cluster Messier 93 lies about 3400 light years away towards the constellation Puppis. Most of its 1000-plus member stars lie close to its center, which may have allowed the cluster to maintain itself as a cohesive unit to its current old age of about 380 million years. The two bright red stars at lower right are 8th magnitude CD-23 6067 and HD 62679. The latter is a K-type evolved giant.
(michael allen)

NGC 288

Globular cluster NGC 288.
Globular cluster NGC 288 is about 23600 light years away towards the constellation Sculptor. Being so far away it is challenging to image in a small telescope. The red stars in the center of this image shine with about 15th magnitude. This cluster is the subject of intense study due to what seems to be distinct stellar populations within in.
(michael allen)

Messier 103

The open star cluster Messier 103.
Open star cluster Messier 103 is in the disk of the Milky Way towards the constellation of Cassiopeia. It is quite young, only 25 million years. The bright red star is BD+59 274, an M-class supergiant near the end of its lifetime.
(michael allen)

NGC 3766

Open cluster NGC 3766.
Open cluster NGC 3766 is about 7200 light years away towards the constellation of Centaurus. It is a small cluster with perhaps a few 100 member stars. Notable stars include the bright red HD 306799, a highly evolved M-class supergiant shining at 7th magnitude. The bright star at center bottom is 6th magnitude HD 100943, a B-type supergiant whose spectrum shows emission lines, indicative of a high temperature and low density gas shell surrounding this star.
(michael allen)

NGC 3293

Open cluster NGC 3293.
Open cluster 3293 is about 8700 light years away towards the constellation Carina. It is in a dusty and actively star-forming region of the Milky Way that includes many famous nebulae. The red star is 7th magnitude V361 Car, an M-class supergiant. In the lower left corner is 8th magnitude HD 92044, a high temperature evolved B II type star. At upper right is 6th magnitude HD 91943, a B-type pulsating variable star.
(michael allen)

NGC 362

Globular cluster NGC 362.
Globular cluster NGC 362 is about 40,000 light years away towards the constellation of Tucana. It is fairly bright and compact and can be found with binoculars in a dark sky.
(michael allen)

NGC 5927

NGC 5927 is a globular cluster.
NGC 5927 is a globular cluster in the Milky Way, located towards the southern constellation of Lupus (the Wolf), and only 5 degrees above the galactic equator. It is about 25,000 light years distant. It is relatively bright at 7th magnitude, easily within the range of a small telescope. Its estimated age of about 12 billion years is about average for globular clusters.
(michael allen)

NGC 4755

Open cluster NGC 4755.
Looking like a mini-Orion, NGC 4755 is an open cluster located about 7000 ly away towards the constellation Crux. It is also called the Jewel Box. Its brightest star (upper right corner) is 5th magnitude HD 111904, a blue supergiant. The reddest star is 7th magnitude DU Cru, an M-type supergiant.
(michael allen)

NGC 6067

Open cluster NGC 6067.
Open cluster NGC 6067 is one of the richest clusters clusters in the Milky Way. It is about 7400 light years away towards the southern constellation Norma. The dozen or more birghtest stars in this image are 10th magnitude or brighter. The age of about 100 million years means these brightest stars are evolved giants of about 6 times the mass of our Sun. Notable stars include the brightest blue star just lower left of center, BD-53 6479, a B III type star with a peculiar spectrum. The brightest star, just upper right of center, is V340 Norma, a delta cepheid type variable star with a period of 11.2888 days.
(michael allen)

IC 4651

Open cluster IC 4651.
Open cluster IC 4651 is only 3000 light years away in the southern Milky Way towards the constellation of Ara. An older cluster, many of its stars have completed their evolution to become white dwarfs (not visible here). The brightest star is about 9th magnitude.
(michael allen)

NGC 6397

The globular cluster NGC 6397.
The globular cluster NGC 6397 is one of the oldest in the Milky Way. It is located about 8,000 light years away in the southern skies towards the constellation of Ara. The stars are more loosely bound than typical globulars. The fainter bluish stars are horizontal giants.
(michael allen)

NGC 6281

Open star cluster NGC 6281.
Open star cluster 6281 lies about 1700 light years away towards the constellation of Scorpius. The brighter stars shine at 9th magnitude. The central, red, brightet star is called HD 322658. It is an 8th magnitude K III type evolved giant star.
(michael allen)