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, and ...
of
star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
s in the southern
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
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 in 1764. This 8th magnitude cluster is a challenge to find in ideal skies with typical
binoculars
Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...
, 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 opt ...
device. It is south-southwest of the open cluster
Messier 11 Messier may refer to:
People with the surname
*Charles Messier, French astronomer
*Éric Messier, former NHL defenseman
*George Messier, French inventor
*Jean-Marie Messier, former CEO of Vivendi Universal
*Marc Messier, Canadian actor from Quebec
...
and is across.
[ About 25 stars are visible in a telescope with a aperture.][
M26 spans a linear size of 22][ ]light year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s 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 year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s 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 11[ and the age of this cluster has been calculated to be 85.3][ million years. It includes one known ]spectroscopic binary
A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separa ...
system.[
An interesting feature of M26 is a region of low ]star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
density near the nucleus. A hypothesis was that it was caused by an obscuring cloud of interstellar matter between us and the cluster, but a paper by James Cuffey
James Cuffey (October 8, 1911 – May 30, 1999) was an American astronomer. He specialized in photoelectric photometry and held the patent on the Cuffey Iris Photometer, an instrument used in stellar photographic photometry.
Born in Chicago, ...
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)
See also
* List of Messier objects
Footnotes and references
Footnotes
References
External links
Messier 26, SEDS Messier pages
*
{{DEFAULTSORT:Messier 26
Messier 026
Carina–Sagittarius Arm
Messier 026
026
6 (six) is the natural number following 5 and preceding 7. It is a composite number and the smallest perfect number.
In mathematics
Six is the smallest positive integer which is neither a square number nor a prime number; it is the second small ...
Messier 026
17640620