到現(xiàn)在為止,，天文學(xué)家只能夠在形成行星的星盤的灼熱的內(nèi)測區(qū)域探測到水蒸氣。
但是在歐洲航天局赫歇爾空間天文臺,，一組研究人員在某個這樣的形成行星的星盤的外部發(fā)現(xiàn)了一個大型的冷水蒸氣的儲庫,。
事實上，這一水蒸氣意味著存在的水冰晶量足以填充相當(dāng)于地球海洋質(zhì)量的數(shù)千倍的量,。
Michiel Hogerheijde及其同事所報告的這一發(fā)現(xiàn)存在于一個形成行星的星盤中,，該星盤所環(huán)繞運行的恒星叫做TW Hydra，它大約有1000萬年的星齡,，距離地球約175光年,。 研究人員解釋說，這些形成行星的星盤的外圍,，即發(fā)現(xiàn)冰凍水的地方,，所代表的是據(jù)認為是與形成彗星和巨大行星相同的區(qū)域。 （大多數(shù)的研究人員相信,，由冰覆蓋的彗星和小行星第一次將水帶到了地球,。） 這些新的發(fā)現(xiàn)補充了我們對宇宙中行星形成和沖擊輸水的理解。
一篇由Rachel Akeson撰寫的觀點欄目對這一發(fā)現(xiàn)做了更為詳盡的解釋并對其影響做了討論,。（生物谷 Bioon.com）
doi:10.1126/science.1208931
PMC:
PMID:
Detection of the Water Reservoir in a Forming Planetary System
Michiel R. Hogerheijde, Edwin A. Bergin, Christian Brinch1, L. Ilsedore Cleeves2, Jeffrey K. J. Fogel2, Geoffrey A. Blake3, Carsten Dominik4, Dariusz C. Lis, Gary Melnick, David Neufeld, Olja Pani?, John C. Pearson9, Lars Kristensen1, Umut A. Y?ld?z1, Ewine F. van Dishoeck
Icy bodies may have delivered the oceans to the early Earth, yet little is known about water in the ice-dominated regions of extrasolar planet-forming disks. The Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory has detected emission lines from both spin isomers of cold water vapor from the disk around the young star TW Hydrae. This water vapor likely originates from ice-coated solids near the disk surface, hinting at a water ice reservoir equivalent to several thousand Earth oceans in mass. The water’s ortho-to-para ratio falls well below that of solar system comets, suggesting that comets contain heterogeneous ice mixtures collected across the entire solar nebula during the early stages of planetary birth.
