帕罗马12

帕罗马 12是位于摩羯座方向上的一个球状星团,它处于银河系的银晕内。

帕罗马12
哈伯太空望远镜拍摄的帕罗马12,视场3.36'。
观测数据(J2000 历元)
分类XII
星座摩羯座
赤经21h 46m 38.84s[1]
赤纬–21° 15′ 09.4″[1]
距离63.6 ± 2.9 kly(19.50 ± 0.89 kpc[2]
视星等 (V)11.99
视直径(V)17′.4
物理性质
Mass1.59×104[3] M
半径162 ± 8 ly[4]
金属量–0.85[3] dex
估计年龄6.5 Gyr[5]
其它名称GCl 123[6]

它在国家地理学会-帕洛马山天文台巡天调查中首度被罗伯特·乔治·哈灵顿弗里茨·兹威基在干片中发现[7],它被归类为球状星团。但是兹威基相信它的本质是本星系群邻近的一个矮星系。它是相对年轻的星团,年龄大约只有比银河系中大多数球状星团年轻约30%[2]。它有丰富的金属量,大约是[Fe/H] ~= -0.8[5]。它的平均亮度是Mv = -4.48.[8]

基于自行的研究,这个集团在2000年被认为是在1.7亿年前从人马座矮椭球星系捕获的[9]。现在,一般认为它是人马座矮星系的成员之一 (Cohen 2004, Sbordone et al. 2006)[5]。估计它的年龄为6.5亿岁[5]

参考资料

  1. ^ 1.0 1.1 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. 
  2. ^ 2.0 2.1 Rosenberg, A.; et al, Young Galactic globular clusters II. The case of Palomar 12, Astronomy and Astrophysics, 1998, 339: 61–69, Bibcode:1998A&A...339...61R, arXiv:astro-ph/9809112 . 
  3. ^ 3.0 3.1 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. 
  4. ^ distance × sin( diameter_angle / 2 ) = 162 ly. radius
  5. ^ 5.0 5.1 5.2 5.3 Geisler, Doug; et al, Chemical Abundances and Kinematics in Globular Clusters and Local Group Dwarf Galaxies and Their Implications for Formation Theories of the Galactic Halo, The Publications of the Astronomical Society of the Pacific, September 2007, 119 (859): 939–961, Bibcode:2007PASP..119..939G, arXiv:0708.0570 , doi:10.1086/521990. 
  6. ^ SIMBAD Astronomical Object Database, Results for Palomar 12, [2006-11-16], (原始内容存档于2020-05-23). 
  7. ^ Abell, George O. Globular Clusters and Planetary Nebulae Discovered on the National Geographic Society-Palomar Observatory Sky Survey. Publications of the Astronomical Society of the Pacific. 1955, 67 (397): 258. Bibcode:1955PASP...67..258A. doi:10.1086/126815. 
  8. ^ van den Bergh, Sidney. The Luminosity Distribution of Globular Clusters in Dwarf Galaxies. The Astronomical Journal. July 2007, 134 (1): 344–345. Bibcode:2007AJ....134..344V. arXiv:0704.2226 . doi:10.1086/518868. 
  9. ^ D. I. Dinescu; S. R. Majewski; T. M. Girard; K. M. Cudworth. The Absolute Proper Motion of Palomar 12: A Case for Tidal Capture from the Sagittarius Dwarf Spheroidal Galaxy. The Astronomical Journal. 2000, 120 (4): 1892–1905. Bibcode:2000astro.ph..6314D. arXiv:astro-ph/0006314 . doi:10.1086/301552. 

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