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NGC 1851

天球赤道座标星图 5h 14m 6.7s, −40° 2′ 48″
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NGC 1851
NGC 1851的紫外线影像。
观测数据(J2000 历元)
分类II[1]
星座天鸽座
赤经05h 14m 06.76s[2]
赤纬–40° 02′ 47.6″[2]
距离39.5 kly(12.1 kpc[3]
视星等 (V)7.3[4]
视直径(V)11′[4]
物理性质
Mass5.51×105[5] M
金属量−1.27[3] dex
估计年龄9.2 Gyr英语Billion years[6]
其它名称GCl 9[7]、ESO 305-SC 016[8]Caldwell 73、Melotte 30

NGC 1851(也称为Caldwell 73[9]位于天鸽座的南部,是一个相对巨大的[3]球状星团。天文学家詹姆士·敦洛普描述它不是非常明亮,但非常大,圆形,分辨率很好,明显由恒星组成[4]。它距离太阳 39.5千光年,距离银河中心 54.1千光年[3]。星团沿着一个高度偏心的轨道穿过银河系,其离心率约为0.7[10]

这个物体在夏普力-索耶集中度分类法中属于II[1],显示恒星密集的向中心集中。它是已知的银河球状星团中密度最高的星团之一[3]。恒星成分显示了两个独立的次巨星群体,较亮的分支更集中在星团的外部区域[10]。估计NGC 1851的年龄约为92亿年[6],质量为太阳的551,000倍[5]

星团周围是一个漫射的恒星晕,向外延伸到{}{Val | 240 | u=pc}或更大的半径。这一特征,如果再加上缺乏潮汐尾或相关的星流,表明星团可能是一个剥离的矮星系核,类似于被银河系吸积半人马座ω[3];但是潮汐尾仍然存在[11]。 该星团也可能是两个独立星团合并的结果,但它们需要具有相同的金属丰度(天文学家所谓称氢和氦之外的元素丰度)。这一事实使得这种情况不太可能发生[10]

PSR J0514-4002A是NGC 1851中的毫秒脉冲星,它正围绕着一颗可能也是中子星的大质量天体运行。这一对的轨道周期为18.8日,离心率为0.89[12]。在星团中已经发现了43颗天琴座RR型变星,这表明这是一个Oosterhoff I型星团,但其性质与II型相似。已经观察到两种水平分支星的种群,其年龄相差约20亿年[13]。对红巨星分支成员恒星的光谱分析表明,星团中实际上有三种不同的恒星群[14]

参考资料

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  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. 
  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可免费查阅, doi:10.1088/0004-6256/140/6/1830. 
  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可免费查阅, doi:10.1093/mnras/stx2353. 
  4. ^ 4.0 4.1 4.2 SEDS NGC Catalog Online. Results for NGC 1851. [2011-01-09]. (原始内容存档于2020-11-27). 
  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可免费查阅, doi:10.1088/0004-637X/742/1/51. 
  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可免费查阅, doi:10.1111/j.1365-2966.2008.12908.x. 
  7. ^ NGC 1851. SIMBAD. 斯特拉斯堡天文资料中心. 
  8. ^ NASA/IPAC Extragalactic Database. Results for NGC 1851. [2011-01-09]. (原始内容存档于2019-08-15). 
  9. ^ O'Meara, Stephen James, Deep-Sky Companions: The Caldwell Objects, Cambridge University Press: 344, 2016, ISBN 9781107083974. 
  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可免费查阅, 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可免费查阅 
  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可免费查阅, doi:10.1093/mnras/stz2645. 
  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可免费查阅, doi:10.3847/1538-3881/aa94c3, 233. 
  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可免费查阅, doi:10.1088/0067-0049/216/1/19, 19. 

外部链接

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