梅西耶23

M 23
M 23
	在人馬座的疏散星團M23。
觀測資料 (J2000 曆元)
星座	人馬座
赤經	17h 57m 04s
赤緯	−18° 59′ 06″
距離	2,050 ly（628 pc）
視星等 (V)	5.5
視大小 (V)	35′
物理特徵
質量	1,206 M☉
半徑	8 ly
估計年齡	330±100 myr
其他特徵	M23、NGC 6494、 Cr 356、C 1753-190
	相關條目：疏散星團、NGC天體表

M23，也稱為NGC 6494，是靠近人馬座這個星座西北方的一個疏散星團 ^[7]。它是查爾斯·梅西耶於1764年6月20日發現的^[3]。在良好的觀測環境下，可以用雙筒望遠鏡或中等大小的望遠鏡看見它^[3]。它位於大範圍的氣體含塵埃雲的前面，但與它們似乎沒有關連^[4]。它在太陽運行平面的5度之內，因此有時會被月球遮蔽到^[8]。

這個星團的中心距離地球約2,050光年，估計成員的數量在169^[9]到414，直接計數的質量為7033239819129999999♠1,206 M_☉；使用維里定理推算的質量則為7033264874859999999♠1,332 M_☉ ^[4]。推測星團的年齡在3.3億年，與太陽比較的金屬量 [Fe/H] = −0.04^[5]。最亮的恆星視星等為+9.3^[10]，成員中有5顆是紅巨星的候選者^[11]，遠在南方的人馬座VV是橙色的變星^[a]，是漸近巨星支的候選者^[12]。

有一顆6等星顯示在圖的右上角，也就是在西北方的遠處，這是一顆前景星：HD 163245（HR 6679）。它的視差偏移是6992479538908259065♠9.8912±0.0518 mas，考慮到自行，這意味著它的距離大約在101秒差距（330光年）之外^[13]。

圖集

顯示M23位置的星圖。

註解和參考資料

註解

^ 在藍白色的7等星HD 163427東側

參考資料

^ Wu, Zhen-Yu; et al, The orbits of open clusters in the Galaxy, Monthly Notices of the Royal Astronomical Society, November 2009, 399 (4): 2146–2164, Bibcode:2009MNRAS.399.2146W, arXiv:0909.3737  , doi:10.1111/j.1365-2966.2009.15416.x.
^ ^2.0 ^2.1 Kharchenko, N. V.; et al, Astrophysical parameters of Galactic open clusters, Astronomy and Astrophysics, 2005, 438 (3): 1163–1173, Bibcode:2005A&A...438.1163K, arXiv:astro-ph/0501674  , doi:10.1051/0004-6361:20042523.
^ ^3.0 ^3.1 ^3.2 Thompson, Robert; Thompson, Barbara, Illustrated Guide to Astronomical Wonders: From Novice to Master Observer, DIY science, O'Reilly Media, Inc.: 408, 2007 [2021-08-20], ISBN 978-0596526856, （原始內容存檔於2023-07-28）
^ ^4.0 ^4.1 ^4.2 McNamara, B. J.; Sanders, W. L., A virial mass determination of the open cluster NGC 6494, Astronomy and Astrophysics, February 1983, 118 (2): 361–362, Bibcode:1983A&A...118..361M.
^ ^5.0 ^5.1 Netopil, M.; Paunzen, E.; Heiter, U.; Soubiran, C., On the metallicity of open clusters. III. Homogenised sample, Astronomy & Astrophysics, 2016, 585: A150, Bibcode:2016A&A...585A.150N, arXiv:1511.08884  , doi:10.1051/0004-6361/201526370.
^ M 23. SIMBAD. 斯特拉斯堡天文資料中心.
^ Gilmour, Jess K., The Practical Astronomer's Deep-sky Companion, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media: 121, 2003, ISBN 978-1852334741.
^ Ridgway, S. T.; et al, Twenty-eight angular diameters for late-type stars by the lunar occultation technique, Astronomical Journal, February 1979, 84: 247–256, Bibcode:1979AJ.....84..247R, doi:10.1086/112414. See VV Sgr.
^ Sanders, W. L.; Schroeder, R., Membership in the open cluster NGC 6494, Astronomy and Astrophysics, August 1980, 88: 102–107, Bibcode:1980A&A....88..102S.
^ Sanders, W. L., UBV photometry of NGC 6494 and metallicity considerations, Astronomy and Astrophysics Supplement Series, September 1990, 84 (3): 615–618, Bibcode:1990A&AS...84..615S.
^ Claria, J. J.; Lapasset, E., Multicolour photometry of red giants in three southern open clusters, Monthly Notices of the Royal Astronomical Society, November 15, 1989, 241 (2): 301–310, Bibcode:1989MNRAS.241..301C, doi:10.1093/mnras/241.2.301 
^ Jura, M., Mass-losing red giants in open clusters, Astrophysical Journal, Part 1, February 1987, 313: 743–749, Bibcode:1987ApJ...313..743J, doi:10.1086/165012.
^ Brown, A. G. A.; Vallenari, A.; Prusti, T.; de Bruijne, J. H. J.; et al. Gaia Data Release 2. Summary of the contents and survey properties. Astronomy & Astrophysics. 2018. Bibcode:2018A&A...616A...1G. arXiv:1804.09365  . doi:10.1051/0004-6361/201833051. VizieR中此天體在蓋亞望遠鏡第二批數據發布的記錄

外部連結

Messier 23, SEDS Messier pages （頁面存檔備份，存於網際網路檔案館）
WikiSky上關於梅西耶23的內容：DSS2, SDSS, GALEX, IRAS, 氫α, X射線, 天文照片, 天圖, 文章和圖片

[12] 在藍白色的7等星HD 163427東側

[Wu2009-1] Wu, Zhen-Yu; et al, The orbits of open clusters in the Galaxy, Monthly Notices of the Royal Astronomical Society, November 2009, 399 (4): 2146–2164, Bibcode:2009MNRAS.399.2146W, arXiv:0909.3737  , doi:10.1111/j.1365-2966.2009.15416.x.

[kharchenko2005-2] 2.0 ^2.1 Kharchenko, N. V.; et al, Astrophysical parameters of Galactic open clusters, Astronomy and Astrophysics, 2005, 438 (3): 1163–1173, Bibcode:2005A&A...438.1163K, arXiv:astro-ph/0501674  , doi:10.1051/0004-6361:20042523.

[Thompson2007-3] 3.0 ^3.1 ^3.2 Thompson, Robert; Thompson, Barbara, Illustrated Guide to Astronomical Wonders: From Novice to Master Observer, DIY science, O'Reilly Media, Inc.: 408, 2007 [2021-08-20], ISBN 978-0596526856, （原始內容存檔於2023-07-28）

[McNamara1983-4] 4.0 ^4.1 ^4.2 McNamara, B. J.; Sanders, W. L., A virial mass determination of the open cluster NGC 6494, Astronomy and Astrophysics, February 1983, 118 (2): 361–362, Bibcode:1983A&A...118..361M.

[netopil2016-5] 5.0 ^5.1 Netopil, M.; Paunzen, E.; Heiter, U.; Soubiran, C., On the metallicity of open clusters. III. Homogenised sample, Astronomy & Astrophysics, 2016, 585: A150, Bibcode:2016A&A...585A.150N, arXiv:1511.08884  , doi:10.1051/0004-6361/201526370.

[SIMBAD-6] M 23. SIMBAD. 斯特拉斯堡天文資料中心.

[Gilmour2003-7] Gilmour, Jess K., The Practical Astronomer's Deep-sky Companion, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media: 121, 2003, ISBN 978-1852334741.

[Ridgway1979-8] Ridgway, S. T.; et al, Twenty-eight angular diameters for late-type stars by the lunar occultation technique, Astronomical Journal, February 1979, 84: 247–256, Bibcode:1979AJ.....84..247R, doi:10.1086/112414. See VV Sgr.

[Sanders1980-9] Sanders, W. L.; Schroeder, R., Membership in the open cluster NGC 6494, Astronomy and Astrophysics, August 1980, 88: 102–107, Bibcode:1980A&A....88..102S.

[Sanders1990-10] Sanders, W. L., UBV photometry of NGC 6494 and metallicity considerations, Astronomy and Astrophysics Supplement Series, September 1990, 84 (3): 615–618, Bibcode:1990A&AS...84..615S.

[Claria1989-11] Claria, J. J.; Lapasset, E., Multicolour photometry of red giants in three southern open clusters, Monthly Notices of the Royal Astronomical Society, November 15, 1989, 241 (2): 301–310, Bibcode:1989MNRAS.241..301C, doi:10.1093/mnras/241.2.301 

[Jura1987-13] Jura, M., Mass-losing red giants in open clusters, Astrophysical Journal, Part 1, February 1987, 313: 743–749, Bibcode:1987ApJ...313..743J, doi:10.1086/165012.

[14] Brown, A. G. A.; Vallenari, A.; Prusti, T.; de Bruijne, J. H. J.; et al. Gaia Data Release 2. Summary of the contents and survey properties. Astronomy & Astrophysics. 2018. Bibcode:2018A&A...616A...1G. arXiv:1804.09365  . doi:10.1051/0004-6361/201833051. VizieR中此天體在蓋亞望遠鏡第二批數據發布的記錄

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[8]

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[13]

梅西耶23

圖集

相關條目

註解和參考資料

註解

參考資料

外部連結