M70

维基百科,自由的百科全书
跳到导航 跳到搜索
M 70
Messier70-HST-Potw1215a.jpg
哈伯太空望遠鏡拍攝的M70;視場為3.3弧分
Credit: ESA/Hubble和NASA
觀測數據(J2000 曆元)
分類V[1]
星座人馬座
赤經18h 43m 12.76s[2]
赤緯–32° 17′ 31.6″[3]
距離29.4 kly(9.0 kpc[4]
視星等 (V)+9.06[3]
視直徑(V)8.0[5]
物理性質
Mass1.79×105[4] M
半徑34 ly[6]
金屬量–1.35[7] dex
估計年齡12.80 Gyr[7]
其它名稱GCl 101, M70, NGC 6681[3]
參見:球狀星團球狀星團表

M70梅西耶70,也稱為NGC 6681,是在人馬座南側的一個球狀星團[a]梅西耶在1780年8月31日發現它[5]。著名的海爾·波普彗星在1995年7月23日被發現時,就在它的旁邊[8]

它與地球的距離為29,400光年[4],並以6,500光年的距離繞著銀河中心運轉[9]。它的大小和亮度與同在人馬座的鄰居,也是球狀星團的M69大致相同[10]。M70的核心非常小,半徑大約只有0.22 ly(0.068 pc)[11],半光度的半徑則為182.0 ly(55.80 pc)[12]。該星團經歷了核心崩塌,使其質量集中於中心[13],光度分佈遵循幂定律[9]

星團中有兩個不同的恒星群體,每一個群體都顯示出獨特的豐度[14]。已知有五顆變星位於其廣泛的半徑,即潮汐半徑內,所有的這些變星都是天琴座RR型變星[15][16]。這個星團在核心附近可能有兩顆藍離散星 [9]

圖集[编辑]

參考資料和註解[编辑]

  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. ^ 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 NGC 6681. SIMBAD. 斯特拉斯堡天文資料中心. 
  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可免费查阅, doi:10.1088/0004-637X/742/1/51. 
  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 
  6. ^ distance × sin( diameter_angle / 2 ) = 34 ly. radius
  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可免费查阅, doi:10.1111/j.1365-2966.2010.16373.x. 
  8. ^ 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 
  9. ^ 9.0 9.1 9.2 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, Bibcode:1994ApJ...435L..55W, doi:10.1086/187593. 
  10. ^ Frommert, Hartmut; Kronberg, Christine, Globular Cluster M70, SEDS Messier pages (Students for the Exploration and Development of Space (SEDS)), 30 August 2007 [2018-12-04]. 
  11. ^ 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. 
  12. ^ 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可免费查阅, doi:10.1111/j.1365-2966.2008.13739.x. 
  13. ^ 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. 
  14. ^ 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可免费查阅, doi:10.3847/1538-4357/aa7b72, 23. 
  15. ^ 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. 
  16. ^ 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可免费查阅, doi:10.1086/323719. 
  1. ^ 位於茶壺星群的最南端;它的赤緯意味著在北緯58度線以北就看不到它。要觀測到它至少要往北移動到北緯43度線,使它的高度能超過15度,才能在影像不失真的條件下進行仔細的觀測。

外部連結[编辑]

天球赤道座標星圖 18h 43m 12.64s,−32° 17′ 30.8″