M 9 (globular cluster)

It was discovered by Charles Messier in 1764 .

M9 is one of the closest to the center of our galaxy globular clusters, and is located at a distance of 5500 light years from it. The distance from the Earth to the cluster is 25,800 light years. The total luminosity of the cluster is 120,000 times greater than the solar one , the absolute magnitude is −8.04 ^m .

The brightest stars in M 9 have a visible magnitude of 13.5 ^m , which allows them to be seen in medium-sized telescopes . In the cluster, 13 variable stars were found.

It is believed that in such globular clusters are some of the oldest stars in the Galaxy, which appeared when the Universe was still very young. These luminaries are approximately twice as old as the Sun and differ markedly in composition: for example, they have much fewer heavy elements (in astronomy, all elements except hydrogen and helium), in particular oxygen, carbon and iron, which make up the core of our planet. The fact is that heavy elements in the Universe formed much later than the formation of M 9 - in the nuclei of stars and in supernova explosions. ^[2]

This globular cluster is located in the southern part of the constellation Ophiuchus and is available for observation in the middle latitudes of Russia in the summer. It is not difficult to detect it in a rather dark sky with field binoculars , but for a more complete picture of the shape and size, you will need a telescope with an aperture of 100 mm or more. On a moonless night, such a telescope will show a somewhat irregular shape of this cluster, and with sufficient magnification and image quality it will allow its edges (halo) to be resolved to the stars. With apertures greater than 350 mm and magnifications greater than 300x, the star structure of the cluster becomes visible to the very center, the unevenness of their volume distribution.

In March 2012, NASA published a photograph of M 9 taken with the Hubble telescope, which can be seen more than 250 thousand individual stars ^[3] . The cluster M 9 could have a spherical shape, but the gravitational forces of the galactic center slightly distorted its shape. The color of the stars, which is directly related to temperature, is also clearly distinguishable in the image: the redder, the colder, and the bluer, the hotter. A wide range of stellar temperatures can be judged by a very diverse palette. ^[2]

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  M 9 , 2MASS , ~ 2001

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  M 9 , Hubble , 2009

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  M 9 , Hubble , 2012

Near the cluster, in degrees to the northeast, there is a less bright globular cluster NGC 6356 , at about the same distance in the southeast direction - the dim cluster NGC 6342 . This triple of clusters is interspersed with dust nebulae B 64 and B 259, which are visible as dark dips with unsharp borders on a star-rich sky background.

Neighbors in the Sky from Messier Catalog

• M 19 - (to the south) a brighter and larger globular cluster;
• M 107 - (to the west), globular cluster;
• M 10 and M 12 - (to the north) a pair of bright clusters in the center of Ophiuchus;
• M 23 - (east to Sagittarius ) large open cluster;

Sequence of Observation at the Messier Marathon

... M 29 → M 14 → M 9 → M 71 → M 27 ...

Gal. Longitude 5.5444 °
Gal. + 10.7051 °
Distance 25 800 St. years old

• List of Messier objects
• New General Catalog

• Messier 9, SEDS Messier pages