包克雲球

包克雲球（英語：Bok globule）是在恆星形成過程中含有稠密的宇宙塵埃和可能發生氣體雲；在天文學中是孤立，相對較小的暗星雲。包克雲球位於電離氫區（H II區）內，通常質量約為2至50太陽質量^[1]，包含在大約跨越一光年左右的區域內（數量級大約為7047450000000000000♠4.5×10⁴⁷ m³）^[2]。它們含有分子氫、碳氧化物和氦，以及約1%（按質量計）的矽酸鹽粉塵。包克雲球通常導致雙星或多星系統的形成^[3]。

歷史

包克雲球是在1940年代被天文學家巴特·包克首度發現的，在1947年的一篇論文中，包克和E.F. Reilly假設這些雲氣很像是昆蟲的繭，會經歷重力崩塌後形成新的恆星，也就是恆星或星團的誕生^[4]。這個假說很難在觀測上獲得證實，因為內部散發出來的可見光被濃密的黑暗雲氣遮蔽掉而難以看見。1990年，分析在近紅外線的觀測才證實了恆星在包克雲球內誕生^[5]。進一步的觀測顯露出包克雲球內嵌有熱源，有些是哈比—哈羅天體^[6]，和向外噴流的分子氣體^[7]。微米波發射線的研究，也提供了落入的氣體吸積成原恆星的證據^[8]。

包克雲球依然是積極研究的主題，是在自然的宇宙中所知最冷的對象（大约为8K），她們的結構和密度仍有許多神秘之處。目前能運用的方法，是依靠近紅外線消光導出的柱密度和未來的恆星計數，以進一步的探測這些天體。

外部連結

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）

參考文獻

^ 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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歷史

相關條目

外部連結

參考文獻