NGC 1851

NGC 1851
NGC 1851
	NGC 1851的紫外線影像。
觀測數據(J2000 曆元)
分類	II
星座	天鴿座
赤經	05h 14m 06.76s
赤緯	–40° 02′ 47.6″
距離	39.5 kly（12.1 kpc）
視星等 (V)	7.3
視直徑(V)	11′
物理性質
Mass	5.51×105 M☉
金屬量	−1.27 dex
估計年齡	9.2 Gyr（英語：Billion years）
其它名稱	GCl 9、ESO 305-SC 016、 Caldwell 73、Melotte 30
	參見：球狀星團，球狀星團表

NGC 1851（也稱為Caldwell 73）^[9]位於天鴿座的南部，是一個相對巨大的^[3]球狀星團。天文學家詹姆士·敦洛普描述它不是非常明亮，但非常大，圓形，解析度很好，明顯由恆星組成^[4]。它距離太陽 39.5千光年，距離銀河中心 54.1千光年^[3]。星團沿著一個高度偏心的軌道穿過銀河系，其離心率約為0.7^[10]。

這個物體在夏普力-索耶集中度分類法中屬於II^[1]，顯示恆星密集的向中心集中。它是已知的銀河球狀星團中密度最高的星團之一^[3]。恆星成分顯示了兩個獨立的次巨星群體，較亮的分支更集中在星團的外部區域^[10]。估計NGC 1851的年齡約為92億年^[6]，質量為太陽的551,000倍^[5]。

星團周圍是一個漫射的恆星暈，向外延伸到{}{Val | 240 | u=pc}或更大的半徑。這一特徵，如果再加上缺乏潮汐尾或相關的星流，表明星團可能是一個剝離的矮星系核，類似於被銀河系吸積半人馬座ω^[3]；但是潮汐尾仍然存在^[11]。該星團也可能是兩個獨立星團合併的結果，但它們需要具有相同的金屬豐度（天文學家所謂稱氫和氦之外的元素豐度）。這一事實使得這種情況不太可能發生^[10]。

PSR J0514-4002A是NGC 1851中的毫秒脈衝星，它正圍繞著一顆可能也是中子星的大質量天體運行。這一對的軌道週期為18.8日，離心率為0.89^[12]。在星團中已經發現了43顆天琴座RR型變星，這表明這是一個Oosterhoff I型星團，但其性質與II型相似。已經觀察到兩種水平分支星的種群，其年齡相差約20億年^[13]。對紅巨星分支成員恆星的光譜分析表明，星團中實際上有三種不同的恆星群^[14]。

參考資料

^ ^1.0 ^1.1 Shapley, Harlow; Sawyer, Helen B., A Classification of Globular Clusters, Harvard College Observatory Bulletin, August 1927, 849 (849): 11–14, Bibcode:1927BHarO.849...11S.
^ ^2.0 ^2.1 Goldsbury, Ryan; et al, The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters, The Astronomical Journal, December 2010, 140 (6): 1830–1837, Bibcode:2010AJ....140.1830G, arXiv:1008.2755 , doi:10.1088/0004-6256/140/6/1830.
^ ^3.0 ^3.1 ^3.2 ^3.3 ^3.4 ^3.5 ^3.6 Kuzma, P. B.; et al, The outer envelopes of globular clusters. II. NGC 1851, NGC 5824 and NGC 1261*, Monthly Notices of the Royal Astronomical Society, January 2018, 473 (3): 2881–2898, Bibcode:2018MNRAS.473.2881K, arXiv:1709.02915 , doi:10.1093/mnras/stx2353.
^ ^4.0 ^4.1 ^4.2 SEDS NGC Catalog Online. Results for NGC 1851. [2011-01-09]. （原始內容存檔於2020-11-27）.
^ ^5.0 ^5.1 Boyles, J.; et al, Young Radio Pulsars in Galactic Globular Clusters, The Astrophysical Journal, November 2011, 742 (1): 51, Bibcode:2011ApJ...742...51B, arXiv:1108.4402 , doi:10.1088/0004-637X/742/1/51.
^ ^6.0 ^6.1 Koleva, M.; et al, Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting, Monthly Notices of the Royal Astronomical Society, April 2008, 385 (4): 1998–2010, Bibcode:2008MNRAS.385.1998K, arXiv:0801.0871 , doi:10.1111/j.1365-2966.2008.12908.x.
^ NGC 1851. SIMBAD. 斯特拉斯堡天文資料中心.
^ NASA/IPAC Extragalactic Database. Results for NGC 1851. [2011-01-09]. （原始內容存檔於2019-08-15）.
^ O'Meara, Stephen James, Deep-Sky Companions: The Caldwell Objects, Cambridge University Press: 344, 2016, ISBN 9781107083974.
^ ^10.0 ^10.1 ^10.2 Carballo-Bello, Julio A.; et al, Tails and streams around the Galactic globular clusters NGC 1851, NGC 1904, NGC 2298 and NGC 2808, Monthly Notices of the Royal Astronomical Society, February 2018, 474 (1): 683–695, Bibcode:2018MNRAS.474..683C, arXiv:1710.08927 , doi:10.1093/mnras/stx2767.
^ Tails and streams around the Galactic globular clusters NGC 1851, NGC 1904, NGC 2298 and NGC 2808, 2017, arXiv:1710.08927 
^ Ridolfi, A.; et al, Upgraded Giant Metrewave Radio Telescope timing of NGC 1851A: a possible millisecond pulsar - neutron star system, Monthly Notices of the Royal Astronomical Society, December 2019, 490 (3): 3860–3874, Bibcode:2019MNRAS.490.3860R, arXiv:1909.06163 , doi:10.1093/mnras/stz2645.
^ Subramaniam, Annapurni; et al, The Horizontal Branch Population of NGC 1851 as Revealed by the Ultraviolet Imaging Telescope (UVIT), The Astronomical Journal, December 2017, 154 (6), Bibcode:2017AJ....154..233S, arXiv:1710.03730 , doi:10.3847/1538-3881/aa94c3, 233.
^ Lim, Dongwook; et al, Low-resolution Spectroscopy for the Globular Clusters with Signs of Supernova Enrichment: M22, NGC 1851, and NGC 288, The Astrophysical Journal Supplement, January 2015, 216 (1): 13, Bibcode:2015ApJS..216...19L, arXiv:1412.1832 , doi:10.1088/0067-0049/216/1/19, 19.

外部連結

維基共享資源上的相關多媒體資源：NGC 1851
Galex image of NGC 1851 （頁面存檔備份，存於網際網路檔案館）
WikiSky上關於NGC 1851的內容：DSS2, SDSS, GALEX, IRAS, 氫α, X射線, 天文照片, 天圖, 文章和圖片
The globular cluster C 73 （頁面存檔備份，存於網際網路檔案館）
SEDS Milky Way Globular Clusters. Results for NGC 1851. [2011-01-09]. （原始內容存檔於2021-05-14）.

天文學目錄
NGC天體表：	NGC 1849 - NGC 1850 - NGC 1851 - NGC 1852 - NGC 1853
科德韋爾深空天體表：	C71 - C72 - C73 - C74 - C75

[hcob849_11-1] 1.0 ^1.1 Shapley, Harlow; Sawyer, Helen B., A Classification of Globular Clusters, Harvard College Observatory Bulletin, August 1927, 849 (849): 11–14, Bibcode:1927BHarO.849...11S.

[aj140_6_1830-2] 2.0 ^2.1 Goldsbury, Ryan; et al, The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters, The Astronomical Journal, December 2010, 140 (6): 1830–1837, Bibcode:2010AJ....140.1830G, arXiv:1008.2755 , doi:10.1088/0004-6256/140/6/1830.

[Kuzma2018-3] 3.0 ^3.1 ^3.2 ^3.3 ^3.4 ^3.5 ^3.6 Kuzma, P. B.; et al, The outer envelopes of globular clusters. II. NGC 1851, NGC 5824 and NGC 1261*, Monthly Notices of the Royal Astronomical Society, January 2018, 473 (3): 2881–2898, Bibcode:2018MNRAS.473.2881K, arXiv:1709.02915 , doi:10.1093/mnras/stx2353.

[seds-4] 4.0 ^4.1 ^4.2 SEDS NGC Catalog Online. Results for NGC 1851. [2011-01-09]. （原始內容存檔於2020-11-27）.

[apj742_1_51-5] 5.0 ^5.1 Boyles, J.; et al, Young Radio Pulsars in Galactic Globular Clusters, The Astrophysical Journal, November 2011, 742 (1): 51, Bibcode:2011ApJ...742...51B, arXiv:1108.4402 , doi:10.1088/0004-637X/742/1/51.

[mnras385_4_1998-6] 6.0 ^6.1 Koleva, M.; et al, Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting, Monthly Notices of the Royal Astronomical Society, April 2008, 385 (4): 1998–2010, Bibcode:2008MNRAS.385.1998K, arXiv:0801.0871 , doi:10.1111/j.1365-2966.2008.12908.x.

[SIMBAD-7] NGC 1851. SIMBAD. 斯特拉斯堡天文資料中心.

[ned-8] NASA/IPAC Extragalactic Database. Results for NGC 1851. [2011-01-09]. （原始內容存檔於2019-08-15）.

[O'Meara2016-9] O'Meara, Stephen James, Deep-Sky Companions: The Caldwell Objects, Cambridge University Press: 344, 2016, ISBN 9781107083974.

[CarballoBello2018-10] 10.0 ^10.1 ^10.2 Carballo-Bello, Julio A.; et al, Tails and streams around the Galactic globular clusters NGC 1851, NGC 1904, NGC 2298 and NGC 2808, Monthly Notices of the Royal Astronomical Society, February 2018, 474 (1): 683–695, Bibcode:2018MNRAS.474..683C, arXiv:1710.08927 , doi:10.1093/mnras/stx2767.

[11] Tails and streams around the Galactic globular clusters NGC 1851, NGC 1904, NGC 2298 and NGC 2808, 2017, arXiv:1710.08927 

[Ridolfi2019-12] Ridolfi, A.; et al, Upgraded Giant Metrewave Radio Telescope timing of NGC 1851A: a possible millisecond pulsar - neutron star system, Monthly Notices of the Royal Astronomical Society, December 2019, 490 (3): 3860–3874, Bibcode:2019MNRAS.490.3860R, arXiv:1909.06163 , doi:10.1093/mnras/stz2645.

[Subramaniam2017-13] Subramaniam, Annapurni; et al, The Horizontal Branch Population of NGC 1851 as Revealed by the Ultraviolet Imaging Telescope (UVIT), The Astronomical Journal, December 2017, 154 (6), Bibcode:2017AJ....154..233S, arXiv:1710.03730 , doi:10.3847/1538-3881/aa94c3, 233.

[Lim2015-14] Lim, Dongwook; et al, Low-resolution Spectroscopy for the Globular Clusters with Signs of Supernova Enrichment: M22, NGC 1851, and NGC 288, The Astrophysical Journal Supplement, January 2015, 216 (1): 13, Bibcode:2015ApJS..216...19L, arXiv:1412.1832 , doi:10.1088/0067-0049/216/1/19, 19.

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