Messier 107 or M107, also known as NGC 6171 or the Crucifix Cluster, is a very loose

globular cluster A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting ...

in a very mildly southern part of the sky close to the

equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...

Ophiuchus Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellati ...

, and is the last such object in the Messier Catalogue.

Observational history, namings and guide

It was discovered by

Pierre Méchain Pierre François André Méchain (; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep-sky objects and comets. Life Pierre Méchain was bo ...

in April 1782, then independently by

William Herschel Frederick William Herschel ( ; ; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover ...

in 1793. Herschel's son, John, in his 1864 General Catalogue, described it as a "globular cluster of stars, large, very rich, very much compressed, round, well resolved, clearly consisting of stars". It was not until 1947 that

Helen Sawyer Hogg Helen Battles Sawyer Hogg (August 1, 1905 – January 28, 1993) was an American-Canadian astronomer who pioneered research into globular clusters and variable stars. She was the first female president of several astronomical organizations and a ...

added it and three other objects found by Méchain to the modern Catalogue, the latter having contributed several of the suggested observation objects which Messier had verified and added. The cluster is to be found 2.5° south and slightly west of the star Zeta Ophiuchi.

Properties

M107 is close to the

galactic plane The galactic plane is the plane (geometry), plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms ''galactic plane'' and ''galac ...

and about 20,900

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

and from the

Galactic Center The Galactic Center is the barycenter of the Milky Way and a corresponding point on the rotational axis of the galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a ...

. Its orbit is partly as far out as the galactic halo, as is between from the

, the lower figure, the "perigalactic distance" sees it enter and leave the galactic bar. It is an Oosterhoff type I cluster with a

metallicity In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...

of −0.95 and it conforms with the bulk of the halo population. There are 22 known RR Lyrae variable stars in this cluster and a probable SX Phoenicis variable.

Gallery

File:The globular star cluster Messier 107.jpg, The globular star cluster Messier 107 image taken by the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope File:M107map.png, Map showing the location of M107

References and footnotes

External links

SEDS: Globular Cluster M107

Messier 107, Galactic Globular Clusters Database page
{{Ngc65 Globular clusters Ophiuchus

107 107 may refer to: *107 (number), the number *AD 107, a year in the 2nd century AD *107 BC, a year in the 2nd century BC *107 (New Jersey bus) *107 Camilla, a main-belt asteroid *Peugeot 107, a city car See also

*10/7 (disambiguation) *Bohrium, ...

Messier 107 Astronomical objects discovered in 1782 Discoveries by Pierre Méchain