Messier 26, also known as NGC 6694, is an

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, an ...

of stars in the southern constellation of

Scutum The ''scutum'' (; plural ''scuta'') was a type of shield used among Italic peoples in antiquity, most notably by the army of ancient Rome starting about the fourth century BC. The Romans adopted it when they switched from the military formati ...

. It was discovered by

Charles Messier Charles Messier (; 26 June 1730 – 12 April 1817) was a French astronomer. He published an astronomical catalogue consisting of 110 nebulae and star clusters, which came to be known as the ''Messier objects''. Messier's purpose ...

in 1764. This 8th magnitude cluster is a challenge to find in ideal skies with typical binoculars, where it can be, with any modern minimum

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

device. It is south-southwest of the open cluster Messier 11 and is across. About 25 stars are visible in a telescope with a aperture. M26 spans a linear size of 22 light years across with a

tidal radius A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...

of , and is at a distance of 5,160 light years from the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. The brightest star is of

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

11 and the age of this cluster has been calculated to be 85.3 million years. It includes one known spectroscopic binary system. An interesting feature of M26 is a region of low star density near the nucleus. A hypothesis was that it was caused by an obscuring cloud of

interstellar matter In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar ...

between us and the cluster, but a paper by James Cuffey suggested that this is not possible and that it really is a "shell of low stellar space density". In 2015, Michael Merrifield of the University of Nottingham said that there is, as yet, no clear explanation for the phenomenon.

Gallery

File:M26map.png, Map showing the location of M26 (Roberto Mura)

Footnotes and references

Footnotes

References

External links

Messier 26, SEDS Messier pages
* {{DEFAULTSORT:Messier 26 Messier 026 Carina–Sagittarius Arm Messier 026 026 Messier 026 17640620

Gallery

See also

Footnotes and references

Footnotes

References

External links