耀星

耀星（英语：Flare star，中国大陆译作耀星，台湾译作焰星）是一种变星，它可以在短短数分钟内不可预知地急遽增光，有时在几分钟内的改变会大于几个星等以上，并持续几分钟到几小时后又慢慢复原。它被认为与太阳闪焰类似，是由于在恒星大气层内的磁重联。亮度的增加跨越了整个光谱，从X射线到无线电波。第一批耀星（天鹅座V1396和显微镜座AT）是在1924年发现的；然而，最著名的耀星是在1948年发现的鲸鱼座UV 。如今，相似的耀星在变星目录上，像是变星总表都被分类为鲸鱼座UV型变星（使用上缩写为UV）。耀斑可以隔几天就发生^[1] ^[可疑]，或是频率非常低，像巴纳德星。

虽然最近的研究表明质量更小的褐矮星也可能发生闪焰，但大多数的耀星都是暗淡的红矮星。质量更大的猎犬座RS型变星（RS CVn）已知也是耀星，但据了解这些闪焰是由联星系统中的伴星造成的磁场纠缠诱发的。此外，也观察到9颗类似太阳的恒星曾经历闪焰的事件^[2]。曾经有建议指出在类似RS CVn变星诱发闪焰的机制，是有看不见的，大小类似木星的行星，在一个紧密的轨道上绕着恒星运转^[3]。目前在太阳系附近已发现近100颗耀星。

邻近的耀星

本质上，耀星都很暗淡，只能发现距离地球1,000光年以内的^[4]。

半人马座比邻星

距离最接近太阳的邻居，半人马座比邻星，是一颗经由恒星磁场的作用，会随机增加亮度的耀星^[5]。恒星的磁场是由恒星本身的对流产生的，并由此造成闪焰的活动，生成的X射线总辐射量与太阳产生的相似^[6]。

沃夫359

沃夫359是另一颗邻近的耀星（2.39 ± 0.01秒差距）。沃夫359也称为格利泽406或狮子座CN，它是光谱类型为M6.5，辐射出X射线的红矮星^[7]。它是鲸鱼座UV型的耀星^[8]，并且有相对较高的闪焰频率。

它的平均磁场强度大约为7003220000000000000♠2.2 kG（6999200000000000000♠0.2 T），但是在短短的6小时的时间尺度内就会有很大的差异^[9]。相较之下，太阳的磁场强度平均只有7000100000000000000♠1 G（6996099999999999999♠100 µT），但是在太阳黑子活动的区域可以达到7003300000000000000♠3 kG (6999300000000000000♠0.3 T)^[10]。

巴纳德星

巴纳德星是距离太阳第二近的恒星，它也被怀疑是一颗耀星^{[来源请求]}。

TVLM513-46546

质量非常小的TVLM513-46546，只比红矮星的质量下限略重一些。

参考资料

^ 存档副本. [2012-10-08]. （原始内容存档于2016-03-28）.
^ Schaefer, Bradley; King, Jeremy R.; Deliyannis, Constantine P. Superflares on Ordinary Solar-Type Stars. The Astrophysical Journal (Astrophysical Journal). 2000-02, 529 (2): 1026. Bibcode:2000ApJ...529.1026S. arXiv:astro-ph/9909188 . doi:10.1086/308325.
^ Rubenstein, Eric; Schaefer, Bradley E. Are Superflares on Solar Analogues Caused by Extrasolar Planets?. The Astrophysical Journal (Astrophysical Journal). 2000-02, 529 (2): 1031. Bibcode:2000ApJ...529.1031R. arXiv:astro-ph/9909187 . doi:10.1086/308326.
^ Kulkarni SR, Rau A. The Nature of the Deep Lens Survey Fast Transients. Ap J. 2006, 644 (1): L63. Bibcode:2006ApJ...644L..63K. arXiv:astro-ph/0604343 . doi:10.1086/505423.
^ Christian DJ, Mathioudakis M, Bloomfield DS, Dupuis J, Keenan FP. A Detailed Study of Opacity in the Upper Atmosphere of Proxima Centauri. Ap J. 2004, 612 (2): 1140–6. Bibcode:2004ApJ...612.1140C. doi:10.1086/422803.
^ Wood BE, Linsky JL, Müller HR, Zank GP. Observational Estimates for the Mass-Loss Rates of α Centauri and Proxima Centauri Using Hubble Space Telescope Lyα Spectra. Ap J. 2001, 547 (1): L49–L52. Bibcode:2001ApJ...547L..49W. arXiv:astro-ph/0011153 . doi:10.1086/318888.
^ Schmitt JHMM, Fleming TA, Giampapa MS. The X-Ray View of the Low-Mass Stars in the Solar Neighborhood. Ap J. Sep 1995, 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.
^ Gershberg RE, Shakhovskaia NI. Characteristics of activity energetics of he UV Cet-type flare stars. Astrophys Space Sci. 1983, 95 (2): 235–53. Bibcode:1983Ap&SS..95..235G. doi:10.1007/BF00653631.
^ Reiners A, Schmitt JHMM, Liefke C. Rapid magnetic flux variability on the flare star CN Leonis. Astronomy and Astrophysics. 2007, 466 (2): L13–6. Bibcode:2007A&A...466L..13R. arXiv:astro-ph/0703172 . doi:10.1051/0004-6361:20077095.
^ Staff. Calling Dr. Frankenstein! : Interactive Binaries Show Signs of Induced Hyperactivity. National Optical Astronomy Observatory. January 7, 2007 [2006-05-24]. （原始内容存档于2019-06-22）.

外部链接

UV Ceti and the flare stars, Autumn 2003 Variable Star Of The Season （页面存档备份，存于互联网档案馆） prepared by Dr. Matthew Templeton, AAVSO(www.aavso.org)
Stellar Flares （页面存档备份，存于互联网档案馆） - D. Montes, UCM.

[1] 存档副本. [2012-10-08]. （原始内容存档于2016-03-28）.

[2] Schaefer, Bradley; King, Jeremy R.; Deliyannis, Constantine P. Superflares on Ordinary Solar-Type Stars. The Astrophysical Journal (Astrophysical Journal). 2000-02, 529 (2): 1026. Bibcode:2000ApJ...529.1026S. arXiv:astro-ph/9909188 . doi:10.1086/308325.

[3] Rubenstein, Eric; Schaefer, Bradley E. Are Superflares on Solar Analogues Caused by Extrasolar Planets?. The Astrophysical Journal (Astrophysical Journal). 2000-02, 529 (2): 1031. Bibcode:2000ApJ...529.1031R. arXiv:astro-ph/9909187 . doi:10.1086/308326.

[Kulkarni-4] Kulkarni SR, Rau A. The Nature of the Deep Lens Survey Fast Transients. Ap J. 2006, 644 (1): L63. Bibcode:2006ApJ...644L..63K. arXiv:astro-ph/0604343 . doi:10.1086/505423.

[Christian-5] Christian DJ, Mathioudakis M, Bloomfield DS, Dupuis J, Keenan FP. A Detailed Study of Opacity in the Upper Atmosphere of Proxima Centauri. Ap J. 2004, 612 (2): 1140–6. Bibcode:2004ApJ...612.1140C. doi:10.1086/422803.

[Wood-6] Wood BE, Linsky JL, Müller HR, Zank GP. Observational Estimates for the Mass-Loss Rates of α Centauri and Proxima Centauri Using Hubble Space Telescope Lyα Spectra. Ap J. 2001, 547 (1): L49–L52. Bibcode:2001ApJ...547L..49W. arXiv:astro-ph/0011153 . doi:10.1086/318888.

[Schmitt-7] Schmitt JHMM, Fleming TA, Giampapa MS. The X-Ray View of the Low-Mass Stars in the Solar Neighborhood. Ap J. Sep 1995, 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.

[Gershberg-8] Gershberg RE, Shakhovskaia NI. Characteristics of activity energetics of he UV Cet-type flare stars. Astrophys Space Sci. 1983, 95 (2): 235–53. Bibcode:1983Ap&SS..95..235G. doi:10.1007/BF00653631.

[Reiners-9] Reiners A, Schmitt JHMM, Liefke C. Rapid magnetic flux variability on the flare star CN Leonis. Astronomy and Astrophysics. 2007, 466 (2): L13–6. Bibcode:2007A&A...466L..13R. arXiv:astro-ph/0703172 . doi:10.1051/0004-6361:20077095.

[Frankenstein-10] Staff. Calling Dr. Frankenstein! : Interactive Binaries Show Signs of Induced Hyperactivity. National Optical Astronomy Observatory. January 7, 2007 [2006-05-24]. （原始内容存档于2019-06-22）.

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耀星