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Messier 22

Core of Messier 22
Observation data (J2000 epoch)
Class VII
Constellation Sagittarius
Right ascension 18h 36m 24. 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 Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere 21s[1]
Declination -23° 54′ 12. In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either 2″[1]
Distance 10. 6 ± 1. 0 kly (3. A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by 3 ± 0. 3 kpc[2])
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 17[1]
Apparent dimensions (V) 32′. 0
Physical characteristics
Mass kg (105 to 106 M{\odot})
Radius 50 ± 5 ly[3]
VHB 14. The solar mass is a standard way to express Mass in Astronomy, used to describe the masses of other Stars and galaxies. 2
Estimated age 12 Gyr[4]
Notable features One of four globulars known
to contain a planetary nebula.
Other designations NGC 6656, GCl 99[1]
See also: Globular cluster, List of globular clusters
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Messier 22 (also known as M22 or NGC 6656) is an elliptical globular cluster in the constellation Sagittarius near the Galactic bulge region. 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 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 In Astronomy, a bulge is a tightly packed group of Stars The term almost exclusively refers to the central group of stars found in most spiral galaxies. It is one of the brightest globulars that is visible in the night sky.

Contents

History

M22 was one of the first globulars to be discovered in 1665 by Abraham Ihle[2] and it was included in Charles Messier's catalog of comet-like objects in 1764. Johann Abraham Ihle ( June 14, 1627 – c1699 was a German Amateur astronomer who discovered the first known Globular cluster, 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 was one of the first globular clusters to be carefully studied first by Harlow Shapley in 1930[5] and then by Halton Arp and William G. Harlow Shapley ( November 2 1885 &ndash October 20 1972) was an American Astronomer. Year 1930 ( MCMXXX) was a Common year starting on Wednesday (link will display 1930 calendar of the Gregorian calendar. Halton Christian Arp (aka "Chip" is an American Astronomer. Melbourne in 1959. The year 1959 ( MCMLIX) was a Common year starting on Thursday (link will display full calendar of the Gregorian calendar. [6] Because of the large color spread of its red giant branch (RGB) sequence, which is similar to that observed in Omega Centauri, it became the object of intense scrutiny starting in 1977 with James E. A red giant is a luminous Giant star of low or intermediate mass (roughly 0 Omega Centauri or NGC 5139 is a Globular cluster of Stars seen in the constellation of Centaurus, discovered by Edmond Halley in Also 1977 (album by Ash. Year 1977 ( MCMLXXVII) was a Common year starting on Saturday (link displays Hesser et al. [7][2]

Characteristics

M22 is one of the nearer globular clusters to Earth at a distance of about 10,600 light-years away. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by It spans 32' on the sky which translates to a spatial diameter of 99 ± 9 light-years. 32 variable stars have been recorded in M22. For the astronomical object see Variable star. Variable Star is a 2006 novel written by Spider Robinson It is projected in front of the galactic bulge and is therefore useful for its microlensing effect on the background stars in the bulge. Gravitational microlensing is an astronomical phenomenon due to the Gravitational lens effect [4]

Despite its relative proximity to us, this metal-poor cluster's light is limited by dust extinction. In Astronomy and Physical cosmology, the metallicity of an object is the proportion of its matter made up of Chemical elements other than Hydrogen Extinction is a term used in Astronomy to describe the absorption and Scattering of Electromagnetic radiation emitted by Astronomical objects [8]

Planetary Nebula

M22 is unique in that it is one of only four globulars (the others being M15, NGC 6441 and Palomar 6) that are known to contain a planetary nebula (PN). Globular Cluster M15 (also known as Messier Object 15 or NGC 7078) is a Globular cluster in the Constellation 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 It was discovered using the IRAS satellite by Fred Gillett et al. The Infrared Astronomical Satellite ( IRAS) was the first-ever space-based Observatory to perform a survey of the entire Sky at Infrared in 1986 as a pointlike source (IRAS 18333-2357)[9] and subsequently identified as a PN in 1989 by Gillett et al. [10] The PN's central star is a blue star. In Astronomy, stellar classification is a classification of Stars based initially on photospheric temperature and its associated Spectral characteristics The age of the PN is estimated to be a mere ~6,000 years old. [2]

External links

References

  1. ^ a b c d SIMBAD Astronomical Database. Results for NGC 6656. Retrieved on 2006-11-15. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 655 - Battle of Winwaed: Penda of Mercia is defeated by Oswiu of Northumbria.
  2. ^ a b c d Monaco, L. ; Pancino, E. ; Ferraro, F. R. ; Bellazzini, M. (2004). "Wide-field photometry of the Galactic globular cluster M22". Monthly Notices of the Royal Astronomical Society 349 (4): 1278-1290. doi:10.1111/j.1365-2966.2004.07599.x. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  3. ^ distance × sin( diameter_angle / 2 ) = 50 ly. radius
  4. ^ a b Gaudi, B. Scott (2002). "Interpreting the M22 Spike Events". The Astrophysical Journal 566 (1): 452-462. doi:10.1086/338041. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  5. ^ Shapley, Harlow (1930). "The Mass-Spectrum Relation for Giant Stars in the Globular Cluster Messier 22". Harvard College Observatory Bulletin 874: 4-9.  
  6. ^ Arp, H. C. ; Melbourne, W. G. (1959). "Color-magnitude diagram for the globular cluster M22". The Astronomical Journal 64: 28.  
  7. ^ Hesser, J. E. ; Hartwick, F. D. A. ; McClure, R. D. (1977). "Cyanogen strengths and ultraviolet excesses of evolved stars in 17 globular clusters from DDO photometry.". Astrophys. J. , Suppl. Ser. 33: 471. doi:10.1086/190438. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  8. ^ I. Ivans, C. Sneden, G. Wallerstein, R. P. Kraft, J. E. Norris, J. P. Fulbright, and G. Gonzalez (2004). "On the Question of a Metallicity Spread in Globular Cluster M22 (NGC 6656)". Societa Astronomica Italiana 75: 286.  
  9. ^ Gillett, F. C. ; Neugebauer, G. ; Emerson, J. P. ; Rice, W. L. (January 15, 1986). Events 588 BC - Nebuchadrezzar II of Babylon lays siege to Jerusalem under Zedekiah 's reign Year 1986 ( MCMLXXXVI) was a Common year starting on Wednesday (link displays 1986 Gregorian calendar) "IRAS 18333-2357 - an unusual source in M22". Astrophysical Journal, Part 1 (ISSN 0004-637X), NASA-supported research. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program 300: 722-728.  
  10. ^ Cohen, J. G. ; Gillett, F. C. (November 15, 1989). Events 655 - Battle of Winwaed: Penda of Mercia is defeated by Oswiu of Northumbria. Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) "The peculiar planetary nebula in M22". Astrophysical Journal, Part 1 (ISSN 0004-637X), Research supported by California Institute of Technology 346: 803-807. The California Institute of Technology (commonly referred to as Caltech) is a private, Coeducational research university located in Pasadena  
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