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Messier 23

October 20, 2023

Messier 23, also known as NGC 6494, is an open cluster of stars in the northwest of the southern constellation of Sagittarius.[7] It was discovered by Charles Messier in 1764.[a][3] It can be found in good conditions with binoculars or a modestly sized telescope.[3] It is in front of "an extensive gas and dust network", which there may be no inter-association.[4] It is within 5° the sun's position (namely in mid-December) so can be occulted by the moon.[8]

Messier 23
Open cluster Messier 23 in Sagittarius
Observation data (J2000 epoch)
Right ascension17h 57m 04s[1]
Declination−18° 59′ 06″
Distance2,050 ly (628 pc)[2]
Apparent magnitude (V)5.5[3]
Apparent dimensions (V)35′[2]
Physical characteristics
Mass1,206[4] M☉
Radius8 ly
Estimated age330±100 myr[5]
Other designationsM23, NGC 6494,[6] Cr 356, C 1753-190
Associations
ConstellationSagittarius
See also: Open cluster, List of open clusters

The cluster is centered about 2,050 light years away. Estimates for the number of its members range from 169[9] up to 414, with a directly-counted mass of 1,206 M☉; 1,332 M☉ by application of the virial theorem.[4] The cluster is around 330 million years old with a near-solar metallicity of [Fe/H] = −0.04.[5] The brightest component (lucida) is of magnitude 9.3.[10] Five of the cluster members are candidate red giants,[11] while orange variable VV Sgr in the far south,[b] is a candidate asymptotic giant branch star.[12]

A 6th-magnitude star, shown in the top-right corner, figures in the far north-west as a foreground star – HD 163245 (HR 6679). Its parallax shift is 9.8912±0.0518 mas, having taken into account proper motion, which means it is about 101 parsecs (330 ly) away.[13]

Gallery Edit

  •  

    Map showing the location of M23

See also Edit

Footnotes and References Edit

Footnotes Edit

  1. ^ On June 20
  2. ^ east of blue-white 7th magnitude fellow member HD 163427

References Edit

  1. ^ Wu, Zhen-Yu; et al. (November 2009), "The orbits of open clusters in the Galaxy", Monthly Notices of the Royal Astronomical Society, 399 (4): 2146–2164, arXiv:0909.3737, Bibcode:2009MNRAS.399.2146W, doi:10.1111/j.1365-2966.2009.15416.x, S2CID 6066790.
  2. ^ a b Kharchenko, N. V.; et al. (2005), "Astrophysical parameters of Galactic open clusters", Astronomy and Astrophysics, 438 (3): 1163–1173, arXiv:astro-ph/0501674, Bibcode:2005A&A...438.1163K, doi:10.1051/0004-6361:20042523, S2CID 9079873.
  3. ^ a b c Thompson, Robert; Thompson, Barbara (2007), Illustrated Guide to Astronomical Wonders: From Novice to Master Observer, DIY science, O'Reilly Media, Inc., p. 408, ISBN 978-0596526856
  4. ^ a b c McNamara, B. J.; Sanders, W. L. (February 1983), "A virial mass determination of the open cluster NGC 6494", Astronomy and Astrophysics, 118 (2): 361–362, Bibcode:1983A&A...118..361M.
  5. ^ a b Netopil, M.; Paunzen, E.; Heiter, U.; Soubiran, C. (2016), "On the metallicity of open clusters. III. Homogenised sample", Astronomy & Astrophysics, 585: A150, arXiv:1511.08884, Bibcode:2016A&A...585A.150N, doi:10.1051/0004-6361/201526370, S2CID 118382876.
  6. ^ "M 23". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 12, 2018.
  7. ^ Gilmour, Jess K. (2003), The Practical Astronomer's Deep-sky Companion, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media, p. 121, ISBN 978-1852334741.
  8. ^ Ridgway, S. T.; et al. (February 1979), "Twenty-eight angular diameters for late-type stars by the lunar occultation technique", Astronomical Journal, 84: 247–256, Bibcode:1979AJ.....84..247R, doi:10.1086/112414. See VV Sgr.
  9. ^ Sanders, W. L.; Schroeder, R. (August 1980), "Membership in the open cluster NGC 6494", Astronomy and Astrophysics, 88: 102–107, Bibcode:1980A&A....88..102S.
  10. ^ Sanders, W. L. (September 1990), "UBV photometry of NGC 6494 and metallicity considerations", Astronomy and Astrophysics Supplement Series, 84 (3): 615–618, Bibcode:1990A&AS...84..615S.
  11. ^ Claria, J. J.; Lapasset, E. (November 15, 1989), "Multicolour photometry of red giants in three southern open clusters", Monthly Notices of the Royal Astronomical Society, 241 (2): 301–310, Bibcode:1989MNRAS.241..301C, doi:10.1093/mnras/241.2.301
  12. ^ Jura, M. (February 1987), "Mass-losing red giants in open clusters", Astrophysical Journal, Part 1, 313: 743–749, Bibcode:1987ApJ...313..743J, doi:10.1086/165012.
  13. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.

External links Edit

 
Wikimedia Commons has media related to Messier 23.
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  • Messier 23 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images


October 20, 2023
messier, also, known, 6494, open, cluster, stars, northwest, southern, constellation, sagittarius, discovered, charles, messier, 1764, found, good, conditions, with, binoculars, modestly, sized, telescope, front, extensive, dust, network, which, there, inter, . Messier 23 also known as NGC 6494 is an open cluster of stars in the northwest of the southern constellation of Sagittarius 7 It was discovered by Charles Messier in 1764 a 3 It can be found in good conditions with binoculars or a modestly sized telescope 3 It is in front of an extensive gas and dust network which there may be no inter association 4 It is within 5 the sun s position namely in mid December so can be occulted by the moon 8 Messier 23Open cluster Messier 23 in SagittariusObservation data J2000 epoch Right ascension17h 57m 04s 1 Declination 18 59 06 Distance2 050 ly 628 pc 2 Apparent magnitude V 5 5 3 Apparent dimensions V 35 2 Physical characteristicsMass1 206 4 M Radius8 lyEstimated age330 100 myr 5 Other designationsM23 NGC 6494 6 Cr 356 C 1753 190AssociationsConstellationSagittariusSee also Open cluster List of open clustersThe cluster is centered about 2 050 light years away Estimates for the number of its members range from 169 9 up to 414 with a directly counted mass of 1 206 M 1 332 M by application of the virial theorem 4 The cluster is around 330 million years old with a near solar metallicity of Fe H 0 04 5 The brightest component lucida is of magnitude 9 3 10 Five of the cluster members are candidate red giants 11 while orange variable VV Sgr in the far south b is a candidate asymptotic giant branch star 12 A 6th magnitude star shown in the top right corner figures in the far north west as a foreground star HD 163245 HR 6679 Its parallax shift is 9 8912 0 0518 mas having taken into account proper motion which means it is about 101 parsecs 330 ly away 13 Contents 1 Gallery 2 See also 3 Footnotes and References 3 1 Footnotes 3 2 References 4 External linksGallery Edit nbsp Map showing the location of M23See also EditList of Messier objectsFootnotes and References EditFootnotes Edit On June 20 east of blue white 7th magnitude fellow member HD 163427 References Edit Wu Zhen Yu et al November 2009 The orbits of open clusters in the Galaxy Monthly Notices of the Royal Astronomical Society 399 4 2146 2164 arXiv 0909 3737 Bibcode 2009MNRAS 399 2146W doi 10 1111 j 1365 2966 2009 15416 x S2CID 6066790 a b Kharchenko N V et al 2005 Astrophysical parameters of Galactic open clusters Astronomy and Astrophysics 438 3 1163 1173 arXiv astro ph 0501674 Bibcode 2005A amp A 438 1163K doi 10 1051 0004 6361 20042523 S2CID 9079873 a b c Thompson Robert Thompson Barbara 2007 Illustrated Guide to Astronomical Wonders From Novice to Master Observer DIY science O Reilly Media Inc p 408 ISBN 978 0596526856 a b c McNamara B J Sanders W L February 1983 A virial mass determination of the open cluster NGC 6494 Astronomy and Astrophysics 118 2 361 362 Bibcode 1983A amp A 118 361M a b Netopil M Paunzen E Heiter U Soubiran C 2016 On the metallicity of open clusters III Homogenised sample Astronomy amp Astrophysics 585 A150 arXiv 1511 08884 Bibcode 2016A amp A 585A 150N doi 10 1051 0004 6361 201526370 S2CID 118382876 M 23 SIMBAD Centre de donnees astronomiques de Strasbourg Retrieved November 12 2018 Gilmour Jess K 2003 The Practical Astronomer s Deep sky Companion The Patrick Moore Practical Astronomy Series Springer Science amp Business Media p 121 ISBN 978 1852334741 Ridgway S T et al February 1979 Twenty eight angular diameters for late type stars by the lunar occultation technique Astronomical Journal 84 247 256 Bibcode 1979AJ 84 247R doi 10 1086 112414 See VV Sgr Sanders W L Schroeder R August 1980 Membership in the open cluster NGC 6494 Astronomy and Astrophysics 88 102 107 Bibcode 1980A amp A 88 102S Sanders W L September 1990 UBV photometry of NGC 6494 and metallicity considerations Astronomy and Astrophysics Supplement Series 84 3 615 618 Bibcode 1990A amp AS 84 615S Claria J J Lapasset E November 15 1989 Multicolour photometry of red giants in three southern open clusters Monthly Notices of the Royal Astronomical Society 241 2 301 310 Bibcode 1989MNRAS 241 301C doi 10 1093 mnras 241 2 301 Jura M February 1987 Mass losing red giants in open clusters Astrophysical Journal Part 1 313 743 749 Bibcode 1987ApJ 313 743J doi 10 1086 165012 Brown A G A et al Gaia collaboration August 2018 Gaia Data Release 2 Summary of the contents and survey properties Astronomy amp Astrophysics 616 A1 arXiv 1804 09365 Bibcode 2018A amp A 616A 1G doi 10 1051 0004 6361 201833051 Gaia DR2 record for this source at VizieR External links Edit nbsp Wikimedia Commons has media related to Messier 23 Messier 23 SEDS Messier pages Messier 23 on WikiSky DSS2 SDSS GALEX IRAS Hydrogen a X Ray Astrophoto Sky Map Articles and images Portals nbsp Astronomy nbsp Stars nbsp Outer space Retrieved from https en wikipedia org w index php title Messier 23 amp oldid 1170035953, wikipedia, wiki, book, books, library,

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