博克球状体

博克球状体（英语：Bok globule）是在恒星形成过程中含有稠密的宇宙尘埃和可能发生气体云；在天文学中是孤立，相对较小的暗星云。博克球状体位于电离氢区（H II区）内，通常质量约为2至50太阳质量^[1]，包含在大约跨越一光年左右的区域内（数量级大约为7047450000000000000♠4.5×10⁴⁷ m³）^[2]。它们含有分子氢、碳氧化物和氦，以及约1%（按质量计）的硅酸盐粉尘。博克球状体通常导致双星或多星系统的形成^[3]。

历史

博克球状体是在1940年代被天文学家巴特·博克首度发现的，在1947年的一篇论文中，博克和E.F. Reilly假设这些云气很像是昆虫的茧，会经历重力崩塌后形成新的恒星，也就是恒星或星团的诞生^[4]。这个假说很难在观测上获得证实，因为内部散发出来的可见光被浓密的黑暗云气遮蔽掉而难以看见。1990年，分析在近红外线的观测才证实了恒星在博克球状体内诞生^[5]。进一步的观测显露出博克球状体内嵌有热源，有些是哈比—哈罗天体^[6]，和向外喷流的分子气体^[7]。微米波发射线的研究，也提供了落入的气体吸积成原恒星的证据^[8]。

博克球状体依然是积极研究的主题，是在自然的宇宙中所知最冷的对象（大约为8K），她们的结构和密度仍有许多神秘之处。目前能运用的方法，是依靠近红外线消光导出的柱密度和未来的恒星计数，以进一步的探测这些天体。

外部链接

Article from American Scientist （页面存档备份，存于互联网档案馆）（May-June 2001）
A Star in the Making （页面存档备份，存于互联网档案馆）

参考文献

^ Michael Szpir. Bart Bok's Black Blobs. American Scientist. May–June 2001 [2008-11-19]. （原始内容存档于2017-04-24）. Bok globules such as Barnard 68 are only about half a light-year across and weigh in at about two solar masses
^ Clemens, Dan P.; Yun, João Lin; Meyer, Mark H. BOK globules and small molecular clouds – Deep IRAS photometry and (C-12)O spectroscopy. Astrophysical Journal Supplement. March 1991, 75: 877. Bibcode:1991ApJS...75..877C. doi:10.1086/191552.
^ Launhardt, R.; Sargent, A. I.; Henning, T.; Zylka, R.; Zinnecker, H. Binary and multiple star formation in Bok globules. Birth and Evolution of Binary Stars, Poster Proceedings of IAU Symposium No. 200 on The Formation of Binary Stars. Potsdam, Germany: Bo Reipurth and Hans Zinnecker: 103. 10–15 April 2000. Bibcode:2000IAUS..200P.103L.
^ Bok, B. J., Reilly, E. F.（1947）. Small Dark Nebulae, Astrophysical Journal, v.105, p.255
^ Yun J.L., Clemens D.P.（1990）. Star formation in small globules – Bart Bok was correct, Astrophysical Journal, v.365, p.L73
^ Reipurth, B., Heathcote, S., & Vrba, F.（1992）, Star formation in Bok globules and low-mass clouds. IV - Herbig-Haro objects in B335, Astronomy & Astrophysics, v.256, p.225
^ Yun, J. L., & Clemens, D. P.（1992）. Discovery of outflows from young stellar objects in BOK globules, Astrophysical Journal, v.385, p.L21
^ Zhou, S., Evans, N. J., II, Kömpe, C., & Walmsley, C. M.（1993）. Evidence for protostellar collapse in B335, Astrophysical Journal, v.404, p.232

[1] Michael Szpir. Bart Bok's Black Blobs. American Scientist. May–June 2001 [2008-11-19]. （原始内容存档于2017-04-24）. Bok globules such as Barnard 68 are only about half a light-year across and weigh in at about two solar masses

[Clemens91-2] Clemens, Dan P.; Yun, João Lin; Meyer, Mark H. BOK globules and small molecular clouds – Deep IRAS photometry and (C-12)O spectroscopy. Astrophysical Journal Supplement. March 1991, 75: 877. Bibcode:1991ApJS...75..877C. doi:10.1086/191552.

[3] Launhardt, R.; Sargent, A. I.; Henning, T.; Zylka, R.; Zinnecker, H. Binary and multiple star formation in Bok globules. Birth and Evolution of Binary Stars, Poster Proceedings of IAU Symposium No. 200 on The Formation of Binary Stars. Potsdam, Germany: Bo Reipurth and Hans Zinnecker: 103. 10–15 April 2000. Bibcode:2000IAUS..200P.103L.

[4] Bok, B. J., Reilly, E. F.（1947）. Small Dark Nebulae, Astrophysical Journal, v.105, p.255

[5] Yun J.L., Clemens D.P.（1990）. Star formation in small globules – Bart Bok was correct, Astrophysical Journal, v.365, p.L73

[6] Reipurth, B., Heathcote, S., & Vrba, F.（1992）, Star formation in Bok globules and low-mass clouds. IV - Herbig-Haro objects in B335, Astronomy & Astrophysics, v.256, p.225

[7] Yun, J. L., & Clemens, D. P.（1992）. Discovery of outflows from young stellar objects in BOK globules, Astrophysical Journal, v.385, p.L21

[8] Zhou, S., Evans, N. J., II, Kömpe, C., & Walmsley, C. M.（1993）. Evidence for protostellar collapse in B335, Astrophysical Journal, v.404, p.232

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博克球状体

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历史

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外部链接

参考文献