近日，美国国家发射天文台的John J.Tobin与智利迭戈·波塔莱斯大学的Lucas Cieza以及美国西北大学的Patrick D. Sheehan等人合作，发现了富含氘的水在行星形成的圆盘中起着重要作用，与彗星和原恒星有着紧密联系。相关研究结果已于2023年3月8日在国际权威学术期刊《自然》上发表。

该研究报道了从V883 Ori星盘中直接检测到气相水(HDO和H₂¹⁸O)。研究人员测量的中平面水雪线半径约为80AU，与柯伊伯带的尺度相当，且检测到水的半径范围为约160 AU。此外，他们还测得盘中的HDO:H₂O比值为(2.26±0.63)× 10^-3。这一比值与原恒星包层和彗星的比值相当，比地球海洋的比值高出3.1σ。研究人员认为，星盘直接从恒星形成的云中继承了水，这些水被纳入了大型冰体，比如彗星，而没有发生实质性的化学变化。

据悉，水是恒星和行星形成过程中的基本分子，对于催化固体物质的生长和盘状物内星子的形成至关重要。然而，在原行星盘内的水雪线和HDO:H₂O的比例还没有被很好地描述，因为水仅在约160K时升华，这意味着大部分水都冻在了尘埃颗粒上，水雪线半径小于10AU(天文单位)。类太阳的原恒星V883  Ori (M*=1.3M_⊙)正在经历一次吸积爆发，将其光度增加到大约200L_⊙，以前的观测表明其水雪线半径为40-120 AU。

附：英文原文

Title: Deuterium-enriched water ties planet-forming disks to comets and protostars

Author: Tobin, John J., van t Hoff, Merel L. R., Leemker, Margot, van Dishoeck, Ewine F., Paneque-Carreo, Teresa, Furuya, Kenji, Harsono, Daniel, Persson, Magnus V., Cleeves, L. Ilsedore, Sheehan, Patrick D., Cieza, Lucas

Issue&Volume: 2023-03-08

Abstract: Water is a fundamental molecule in the star and planet formation process, essential for catalysing the growth of solid material and the formation of planetesimals within disks. However, the water snowline and the HDO:H₂O ratio within proto-planetary disks have not been well characterized because water only sublimates at roughly 160K，meaning that most water is frozen out onto dust grains and that the water snowline radii are less than 10AU (astronomical units). The sun-like protostar V883 Ori (M*=1.3M_⊙) is undergoing an accretion burst, increasing its luminosity to roughly 200L_⊙, and previous observations suggested that its water snowline is 40–120AU in radius. Here we report the direct detection of gas phase water (HDO and H₂¹⁸O) from the disk of V883 Ori. We measure a midplane water snowline radius of approximately 80AU, comparable to the scale of the Kuiper Belt, and detect water out to a radius of roughly 160AU. We then measure the HDO:H₂O ratio of the disk to be (2.26±0.63)×10^-3. This ratio is comparable to those of protostellar envelopes and comets, and exceeds that of Earth’s oceans by 3.1σ. We conclude that disks directly inherit water from the star-forming cloud and this water becomes incorporated into large icy bodies, such as comets, without substantial chemical alteration.

DOI: 10.1038/s41586-022-05676-z

Source: https://www.nature.com/articles/s41586-022-05676-z