2MASS J18082002−5104378

2MASS J18082002−5104378(缩写为J1808−5104)是一个超贫金属(UMP)联星系统,位于天坛座,距离地球大约1,950 ly(600 pc)[5][6][7],并且是单线光谱联星(SB1)。它是已知最古老的恒星之一,约有135.3亿年的历史,可能是最早的恒星之一。这颗恒星几乎完全由宇宙大爆炸释放的物质组成。一个看不见的微小伴星,一颗低质量的UMP恒星,特别不寻常。

2MASS J18082002−5104378[1]
观测资料
历元 J2000
星座 天坛座[2]
星官
赤经 18h 08m 20.02s
赤纬 −51° 04′ 37.8″
视星等(V) 11.9[3]
特性
演化阶段次巨星 / 红矮星
天体测定
自行 (μ) 赤经:−5.672[4] mas/yr
赤纬:−12.643[4] mas/yr
视差 (π)1.6775 ± 0.0397[4] mas
距离1,950[5][6][7] ly
(600 pc)
详细资料
A
质量0.7599 ± 0.0001[1] M
半径2.44[4] R
表面重力 (log g)3.0[3]
亮度5.311[4] L
温度5,440 ± 100[3] K
金属量 [Fe/H]-4.1[3] dex
年龄13.535±0.002[1] Gyr
B
质量0.14+0.06
−0.01
[1] M
年龄13.535±0.002[1] Gyr
其他命名
Gaia DR2 6702907209758894848[5]
参考数据库
SIMBAD资料

系统

J1808−5104是一颗超贫金属(UMP)星,其对数金属丰度[Fe/H]小于−4,或太阳1/   10,000  的级别[8]。它是一个单线光谱联星,其光谱吸收线径向速度变化被解释为可见恒星的轨道运动。这颗伴星是看不见的,而仅是从轨道上推断出来的[1]

J1808−5104是已知最亮的联星系统超贫金属星[8],是太阳所在星系银河系薄盘”的一部分,但对于这样一颗缺乏金属的古老恒星来说是不寻常的[9]。在13.53 Gyr,这颗恒星是已知最古老的薄盘恒星,比大多数对银河系薄盘年龄的估计要早几十亿年[1]

主星

联星系统的主要组成部分,2MASS J18082002−5104378 A,是一颗比太阳冷,但更大、更亮的次巨星[3]

伴星

看不见的伴星,2MASS J18082002−5104378 B,被认为是一颗红矮星 [5]轨道周期 P = 34.757+0.010
−0.010
日和质量为0.14 M[1]。它是第一颗被发现的低质量超贫金属星,也是宇宙中最古老的恒星之一,约有135.3亿年的历史[5]。它可能是最早的恒星之一,一颗几乎完全由大爆炸释放的物质形成的恒星[1][10][11][9][12][13][14][15]

参考资料

  1. ^ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Schlaufman, Kevin C.; Thompson, Ian B.; Casey, Andrew R. An ultra metal-poor star near the hydrogen-burning limit. The Astrophysical Journal. 5 November 2018, 867 (2): 98. Bibcode:2018ApJ...867...98S. S2CID 54511945. arXiv:1811.00549 . doi:10.3847/1538-4357/aadd97 . 
  2. ^ Finding the constellation which contains given sky coordinates. DJM.cc. 2018 [5 November 2018]. (原始内容存档于2019-08-15). 
  3. ^ 3.0 3.1 3.2 3.3 3.4 Meléndez, Jorge; Placco, Vinicius M.; Tucci-Maia, Marcelo; Ramírez, Iván; Li, Ting S.; Perez, Gabriel. 2MASS J18082002-5104378: The brightest (V = 11.9) ultra metal-poor star. Astronomy and Astrophysics. 2016, 585: L5. Bibcode:2016A&A...585L...5M. S2CID 119240055. arXiv:1601.03462 . doi:10.1051/0004-6361/201527456. 
  4. ^ 4.0 4.1 4.2 4.3 4.4 Brown, A. G. A.; Vallenari, A.; Prusti, T.; de Bruijne, J. H. J.; et al. Gaia Data Release 2. Summary of the contents and survey properties. Astronomy & Astrophysics. 2018. Bibcode:2018A&A...616A...1G. arXiv:1804.09365 . doi:10.1051/0004-6361/201833051.  VizieR中此天体在盖亚望远镜第二批数据发布的记录
  5. ^ 5.0 5.1 5.2 5.3 5.4 One of Milky Way's oldest stars discovered. SciNews.com. 6 November 2018 [6 November 2018]. (原始内容存档于2018-11-06). 
  6. ^ 6.0 6.1 Crockett, Christopher. Puny star might be [a] specimen from [the] early universe. Sky & Telescope. 12 November 2018 [14 November 2018]. (原始内容存档于2018-11-12). 
  7. ^ 7.0 7.1 Williams, Matt. Ancient star found that's only slightly younger than the universe itself. Universe Today. 9 November 2018 [14 November 2018]. (原始内容存档于2024-01-26). 
  8. ^ 8.0 8.1 Ezzeddine, Rana; Frevbel, Anna. Revisiting the iron abundance in the hyper iron-poor star HE 1327−2326 with UV COS/HST data. The Astrophysical Journal. 27 September 2018, 863 (2): 168. Bibcode:2018ApJ...863..168E. S2CID 118918067. arXiv:1807.06153 . doi:10.3847/1538-4357/aad3cb . 
  9. ^ 9.0 9.1 Rosen, Jill. Johns Hopkins scientist finds elusive star with origins close to Big Bang (新闻稿). Johns Hopkins University. 5 November 2018 [5 November 2018]. (原始内容存档于2018-11-06). The newly discovered star's composition indicates that, in a cosmic family tree, it could be as little as one generation removed from the Big Bang. 
  10. ^ Wehner, Mike. Astronomers spot one of the oldest stars ever. BGR. 5 November 2018 [5 November 2018]. (原始内容存档于2018-11-06). 
  11. ^ A tiny old star has a huge impact. SpaceRef.com (新闻稿). Gemini Observatory. 5 November 2018 [6 November 2018]. [永久失效链接]
  12. ^ Johns Hopkins scientist finds elusive star with origins close to Big Bang (新闻稿). Johns Hopkins University. 5 November 2018 [5 November 2018]. (原始内容存档于2018-11-06) –通过EurekAlert!. 
  13. ^ Starr, Michelle. Astronomers have detected one of the oldest stars in the entire universe. ScienceAlert.com. 5 November 2018 [5 November 2018]. (原始内容存档于2018-11-05). 
  14. ^ Irving, Michael. 13.5 billion year old star was born just after the Big Bang - and it's in our neighborhood. NewAtlas.com. 5 November 2018 [5 November 2018]. (原始内容存档于2018-11-05). 
  15. ^ Malewar, Amit. Johns Hopkins scientists may have found one of the universe's oldest stars - One of the universe's oldest stars. TechExplorist.com. 5 November 2018 [5 November 2018]. (原始内容存档于2018-11-05). 

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