Messier 15
M15 photographed by HST
Observation data (J2000 epoch)
Class	IV
Constellation	Pegasus
Right ascension	21h 29m 58. The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. The Shapley–Sawyer Concentration Class is a classification system on a scale of one to twelve using Roman numerals for Globular clusters according to their concentration In common usage a constellation is a group of celestial bodies that are connected together in some arrangement typically stars to form a visible figure or picture Pegasus (ˈpɛɡəsəs is a northern Constellation, named after the mythological winged horse Pegasus. Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere 38s[1]
Declination	+12° 10′ 00. In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either 6″[1]
Distance	33. 6 kly (10. A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by 3 kpc)
Apparent magnitude (V)	+6. History The first direct measurements of an object at interstellar distances were undertaken by German Astronomer Friedrich Wilhelm Bessel in 1838 The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 2
Apparent dimensions (V)	18′. 0
Physical characteristics
Mass	- kg (- M)
Radius	~88 ly[2]
VHB	15. The solar mass is a standard way to express Mass in Astronomy, used to describe the masses of other Stars and galaxies. 83
Estimated age	-
Notable features	steep central cusp
Other designations	NGC 7078, GCl 120[1]
See also: Globular cluster, List of globular clusters
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The central square arcminute of M15 imaged using the lucky imaging technique

Globular Cluster M15 (also known as Messier Object 15 or NGC 7078) is a globular cluster in the constellation Pegasus. The New General Catalogue ( NGC) is the best-known catalogue of Deep sky objects in Amateur astronomy. A globular cluster is a spherical collection of Stars that orbits a galactic core as a Satellite. This is a list of Globular clusters. The apparentmagnitude does not include an extinction correction Lucky imaging (also called lucky exposures) is one form of Speckle imaging used for Astronomical photography. A globular cluster is a spherical collection of Stars that orbits a galactic core as a Satellite. In common usage a constellation is a group of celestial bodies that are connected together in some arrangement typically stars to form a visible figure or picture Pegasus (ˈpɛɡəsəs is a northern Constellation, named after the mythological winged horse Pegasus. It was discovered by Jean-Dominique Maraldi in 1746 and included in Charles Messier's catalog of comet-like objects in 1764. Giovanni Domenico ( Jean-Dominique) Maraldi ( April 17, 1709 – November 14, 1788) was an Italian -born Year 1746 ( MDCCXLVI) was a Common year starting on Saturday (link will display the full calendar of the Gregorian calendar (or a Charles Messier ( June 26, 1730 &ndash April 12, 1817) was a French astronomer most notable for publishing an A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — Year 1764 ( MDCCLXIV) was a Leap year starting on Sunday (link will display the full calendar of the Gregorian calendar (or a It is estimated to be 13. 2 billion years old, one of the oldest globular clusters.

M15 is at a distance of about 33,600 light-years from Earth. A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 It has an absolute magnitude of -9. In Astronomy, absolute magnitude (also known as absolute visual magnitude) is the Apparent magnitude an object would have if it were at a standard 2 which translates to a total luminosity of 360,000 times that of the Sun. Luminosity has different meanings in several different fields of science The Sun (Sol is the Star at the center of the Solar System. Messier 15 is one of the most densely packed globulars known in the Milky Way galaxy. The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Γαλαξίας (Galaxias sometimes referred to simply The core of this cluster has undergone a contraction known as core collapse and it has a central density cusp (just left of centre in image at right), with an enormous number of stars surrounding what may be a central black hole.

Messier 15 contains a rather high number of variable stars; 112 of these are known to reside within its mass of stars. For the astronomical object see Variable star. Variable Star is a 2006 novel written by Spider Robinson There have also been found to be at least 8 pulsars in M15 including one double neutron star system, M15 C. Pulsars are highly magnetized rotating Neutron stars that emit a beam of Electromagnetic radiation in the form of radio waves Moreover, M15 houses one of only four planetary nebulae known in a globular cluster, Pease 1, discovered in 1928. A planetary nebula is an Emission nebula consisting of a glowing shell of Gas and plasma formed by certain types of Stars when they die Year 1928 ( MCMXXVIII) was a Leap year starting on Sunday (link will display full calendar of the Gregorian calendar.

To the amateur astronomer Messier 15 appears as a fuzzy star in the smallest of telescopes. Amateur astronomy, a subset of Astronomy, is a Hobby whose participants enjoy studying and observing celestial objects Historically Astronomy was more concerned with the classification and description of phenomena in the sky while Astrophysics attempted to explain these phenomena A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. Mid to large size telescopes (at least 6 in. /150 mm diameter) will start to reveal individual stars, the brightest of which are of magnitude +12. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 6.

External links

• Messier 15, SEDS Messier pages
• Globular Cluster Photometry With the Hubble Space Telescope. V. WFPC Study of M15's Central density Cusp
• Wikisky.org SDSS image of M15

References