M 5 (globular cluster)

M 5 was discovered by German astronomer Gottfried Kirch in 1702 during his observation of a comet . Charles Messier discovered it in 1764 and considered it to be a nebula without stars. William Herschel identified individual stars in the cluster in 1791 , counting about 200 of them.

Extending 165 light-years across, M 5 is one of the largest known star clusters. The sphere of gravitational influence M 5, (that is, the volume of space in which the stars would be attracted by the cluster, but would not come off the gravitational gravity of the Milky Way) has a radius of about 200 light years. This large cluster belongs to the most massive in the vicinity of our Galaxy , its mass is equivalent to 2 million solar masses.

At 13 billion years old, this cluster is also one of the oldest clusters in the Milky Way Galaxy. The distance from Earth to M 5 is about 24,500 light years. The cluster contains, according to various estimates, from 100,000 to 500,000 stars.

Variable Stars

At least 105 stars in M ​​5 are variable stars, 97 of which are of the RR Lyrae type. Variables such as RR Lyrae, sometimes called “Cluster Variables,” are somewhat similar to Cepheids and therefore can be used as a tool for measuring distances in outer space, since the relationship between the amplitude and the period of brightness changes is well known to them. The brightest and easiest observable variables in M ​​5 change brightness from 10.6 to 12.1 over a period of 26.5 days. The cluster also has a dwarf new star .

In the clear country sky at the new moon M 5, you can try to find with the naked eye as a dull "star" near the star 5 of the Snake . The best observation time in Russia is spring. With binoculars or a spyglass, the cluster is seen as a rounded diffuse cloud. In a telescope, even a small aperture (from 80 mm) with a corresponding increase, individual stars are distinguished. The brightest of them have a visible magnitude of 12.2 ^m . In a telescope with a 100 mm aperture, stars are clearly visible at the edges (about two dozen). At 150 mm, the cluster is a rich swarm of stars. At 200 mm or more, it breaks down into stars almost to the very center and it becomes apparent that the stellar density decreases in unevenness when moving from the center to the edge. Chains of stars line up in a shape resembling a crab or a bug.

Neighbors in the Sky from Messier Catalog

• M 10 and M 12 - (to the east, in Ophiuchus) are two dimmer globular clusters.

Sequence of Observation at the Messier Marathon

... M 13 → M 92 → M 5 → M 57 → M 12 ...

Gal. Longitude 3.8587 °
Gal. + 46.7964 °
Distance 24 500 St. years

• List of Messier objects
• New General Catalog

• Information in English and French from the original “ New General Catalog ”
• Information (Eng.) From the Revised New General Catalog
• SIMBAD
• VizieR (English)
• NASA / IPAC Extragalactic Database
• NGC 5904 Publication List
• M 5, SEDS Messier pages
• Historic observations of M 5
• Astronomy Picture of the Day. Hubble's Messier 5 (English) (April 25, 2014). Date of treatment October 3, 2015.