M70

M 70
M 70
	哈伯太空望远镜拍摄的M70；视场为3.3弧分 ; Credit: ESA/Hubble和NASA
观测数据(J2000 历元)
分类	V
星座	人马座
赤经	18h 43m 12.76s
赤纬	–32° 17′ 31.6″
距离	29.4 kly（9.0 kpc）
视星等 (V)	+9.06
视直径(V)	8.0′
物理性质
Mass	1.79×105 M☉
半径	34 ly
金属量	–1.35 dex
估计年龄	12.80 Gyr
其它名称	GCl 101, M70, NGC 6681
	参见：球状星团，球状星团表

M70或梅西耶70，也称为NGC 6681，是在人马座南侧的一个球状星团^[a]。梅西耶在1780年8月31日发现它^[5]。著名的海尔·波普彗星在1995年7月23日被发现时，就在它的旁边^[9]。

它与地球的距离为29,400光年^[4]，并以6,500光年的距离绕着银河中心运转^[10]。它的大小和亮度与同在人马座的邻居，也是球状星团的M69大致相同^[11]。M70的核心非常小，半径大约只有0.22 ly（0.068 pc）^[12]，半光度的半径则为182.0 ly（55.80 pc）^[13]。该星团经历了核心崩塌，使其质量集中于中心^[14]，光度分布遵循幂定律^[10]。

星团中有两个不同的恒星群体，每一个群体都显示出独特的丰度^[15]。已知有五颗变星位于其广泛的半径，即潮汐半径内，所有的这些变星都是天琴座RR型变星^[8]^[16]。这个星团在核心附近可能有两颗蓝离散星 ^[10]。

图集

哈伯太空望远镜拍摄的M70。
以箭头标示出M70的星图，在正常状况下，地平线的位置在图的南方(下方) (罗伯托·穆拉) 。

参考资料和注解

^ Shapley, Harlow; Sawyer, Helen B., A Classification of Globular Clusters, Harvard College Observatory Bulletin, August 1927, 849 (849): 11–14, Bibcode:1927BHarO.849...11S.
^ 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 NGC 6681. SIMBAD. 斯特拉斯堡天文资料中心.
^ ^4.0 ^4.1 ^4.2 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.
^ ^5.0 ^5.1 Adam, Len, Imaging the Messier Objects Remotely from Your Laptop, The Patrick Moore Practical Astronomy Series, Springer: 304, 2018, Bibcode:2018imor.book.....A, ISBN 978-3319653853
^ distance × sin( diameter_angle / 2 ) = 34 ly. radius
^ ^7.0 ^7.1 Forbes, Duncan A.; Bridges, Terry, Accreted versus in situ Milky Way globular clusters, Monthly Notices of the Royal Astronomical Society, May 2010, 404 (3): 1203–1214, Bibcode:2010MNRAS.404.1203F, arXiv:1001.4289 , doi:10.1111/j.1365-2966.2010.16373.x.
^ ^8.0 ^8.1 Liller, M. H., The variable stars in the field of the globular cluster NGC 6681, Astronomical Journal, October 1983, 88: 1463–1469, Bibcode:1983AJ.....88.1463L, doi:10.1086/113435.
^ Mobberley, Martin, It Came From Outer Space Wearing an RAF Blazer!: A Fan's Biography of Sir Patrick Moore, Springer Science & Business Media: 483, 2013, ISBN 978-3319006093
^ ^10.0 ^10.1 ^10.2 Watson, Alan M.; et al, Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2 (PDF), Astrophysical Journal, Part 2, November 1994, 435 (1): L55–L58 [2021-08-12], Bibcode:1994ApJ...435L..55W, doi:10.1086/187593, （原始内容存档 (PDF)于2022-10-06）.
^ Frommert, Hartmut; Kronberg, Christine, Globular Cluster M70, SEDS Messier pages (Students for the Exploration and Development of Space (SEDS)), 2007-08-30 [2018-12-04], （原始内容存档于2015-03-03）.
^ Djorgovski, S., Physical Parameters of Galactic Globular Clusters, Djorgovski, S. G.; Meylan, G. (编), Structure and Dynamics of Globular Clusters. Proceedings of a Workshop held in Berkeley, California, July 15–17, 1992, to Honor the 65th Birthday of Ivan King 50, San Francisco, California: Astronomical Society of the Pacific: 373, January 1993, Bibcode:1993ASPC...50..373D, ISBN 978-0937707692.
^ Forbes, Duncan A.; et al, Uniting old stellar systems: from globular clusters to giant ellipticals, Monthly Notices of the Royal Astronomical Society, October 2008, 389 (4): 1924–1936, Bibcode:2008MNRAS.389.1924F, arXiv:0806.1090 , doi:10.1111/j.1365-2966.2008.13739.x.
^ Pryor, Carlton; et al, Mass-to-light ratios for globular clusters. I - The centrally concentrated clusters NGC 6624, M28 (NGC 6626), and M70 (NGC 6681), Astronomical Journal, August 1989, 98: 596–610, Bibcode:1989AJ.....98..596P, doi:10.1086/115160.
^ O'Malley, Erin M.; et al, High-resolution Spectroscopic Abundances of Red Giant Branch Stars in NGC 6681, The Astrophysical Journal, September 2017, 846 (1): 15, Bibcode:2017ApJ...846...23O, arXiv:1706.06962 , doi:10.3847/1538-4357/aa7b72, 23.
^ Clement, Christine M.; et al, Variable Stars in Galactic Globular Clusters, The Astronomical Journal, November 2001, 122 (5): 2587–2599, Bibcode:2001AJ....122.2587C, arXiv:astro-ph/0108024 , doi:10.1086/323719.

^ 位于茶壶星群的最南端；它的赤纬意味着在北纬58度线以北就看不到它。要观测到它至少要往北移动到北纬43度线，使它的高度能超过15度，才能在影像不失真的条件下进行仔细的观测。

外部链接

Messier 70, Galactic Globular Clusters Database page （页面存档备份，存于互联网档案馆）
WikiSky上关于M70的内容：DSS2, SDSS, GALEX, IRAS, 氢α, X射线, 天文照片, 天图, 文章和图片

[hcob849_11-1] 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] 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.

[simbad-3] 3.0 ^3.1 ^3.2 NGC 6681. SIMBAD. 斯特拉斯堡天文资料中心.

[apj742_1_51-4] 4.0 ^4.1 ^4.2 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.

[Adam2018-5] 5.0 ^5.1 Adam, Len, Imaging the Messier Objects Remotely from Your Laptop, The Patrick Moore Practical Astronomy Series, Springer: 304, 2018, Bibcode:2018imor.book.....A, ISBN 978-3319653853

[sma-6] stance × sin( diameter_angle / 2 ) = 34 ly. radius

[mnras404_3_1203-7] 7.0 ^7.1 Forbes, Duncan A.; Bridges, Terry, Accreted versus in situ Milky Way globular clusters, Monthly Notices of the Royal Astronomical Society, May 2010, 404 (3): 1203–1214, Bibcode:2010MNRAS.404.1203F, arXiv:1001.4289 , doi:10.1111/j.1365-2966.2010.16373.x.

[Liller1983-8] 8.0 ^8.1 Liller, M. H., The variable stars in the field of the globular cluster NGC 6681, Astronomical Journal, October 1983, 88: 1463–1469, Bibcode:1983AJ.....88.1463L, doi:10.1086/113435.

[Mobberley2013-10] Mobberley, Martin, It Came From Outer Space Wearing an RAF Blazer!: A Fan's Biography of Sir Patrick Moore, Springer Science & Business Media: 483, 2013, ISBN 978-3319006093

[Watson1994-11] 10.0 ^10.1 ^10.2 Watson, Alan M.; et al, Far-ultraviolet imaging of the globular cluster NGC 6681 with WFPC2 (PDF), Astrophysical Journal, Part 2, November 1994, 435 (1): L55–L58 [2021-08-12], Bibcode:1994ApJ...435L..55W, doi:10.1086/187593, （原始内容存档 (PDF)于2022-10-06）.

[Hartmut2011-12] Frommert, Hartmut; Kronberg, Christine, Globular Cluster M70, SEDS Messier pages (Students for the Exploration and Development of Space (SEDS)), 2007-08-30 [2018-12-04], （原始内容存档于2015-03-03）.

[Djorgovski1993-13] Djorgovski, S., Physical Parameters of Galactic Globular Clusters, Djorgovski, S. G.; Meylan, G. (编), Structure and Dynamics of Globular Clusters. Proceedings of a Workshop held in Berkeley, California, July 15–17, 1992, to Honor the 65th Birthday of Ivan King 50, San Francisco, California: Astronomical Society of the Pacific: 373, January 1993, Bibcode:1993ASPC...50..373D, ISBN 978-0937707692.

[Forbes2008-14] Forbes, Duncan A.; et al, Uniting old stellar systems: from globular clusters to giant ellipticals, Monthly Notices of the Royal Astronomical Society, October 2008, 389 (4): 1924–1936, Bibcode:2008MNRAS.389.1924F, arXiv:0806.1090 , doi:10.1111/j.1365-2966.2008.13739.x.

[Pryor1989-15] Pryor, Carlton; et al, Mass-to-light ratios for globular clusters. I - The centrally concentrated clusters NGC 6624, M28 (NGC 6626), and M70 (NGC 6681), Astronomical Journal, August 1989, 98: 596–610, Bibcode:1989AJ.....98..596P, doi:10.1086/115160.

[OMalley2017-16] O'Malley, Erin M.; et al, High-resolution Spectroscopic Abundances of Red Giant Branch Stars in NGC 6681, The Astrophysical Journal, September 2017, 846 (1): 15, Bibcode:2017ApJ...846...23O, arXiv:1706.06962 , doi:10.3847/1538-4357/aa7b72, 23.

[Clement2001-17] Clement, Christine M.; et al, Variable Stars in Galactic Globular Clusters, The Astronomical Journal, November 2001, 122 (5): 2587–2599, Bibcode:2001AJ....122.2587C, arXiv:astro-ph/0108024 , doi:10.1086/323719.

[9] 位于茶壶星群的最南端；它的赤纬意味着在北纬58度线以北就看不到它。要观测到它至少要往北移动到北纬43度线，使它的高度能超过15度，才能在影像不失真的条件下进行仔细的观测。

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