新生恒星围绕着一个距离我们 4.5 亿光年的行星形成盘

这些原恒星喷出的气体与快速的星风发生碰撞。

作者：Laura Baisas

发布时间 2025年2月4日下午2:06 EST

A close-in image of a protoplanetary disc around a newly formed star. Many different wavelengths of light are combined and represented by separate and various colours. A dark line across the centre is the disc, made of opaque dust: the star is hidden in here and creates a strong glow in the centre. A band going straight up is a jet, while other outflows form flares above and below the disc, and a tail coming off to one side. — HH30是一个围绕新形成恒星的原行星盘。许多不同波长的光被组合并以独立的、各种颜色表示。中心的一条暗线是盘，由不透明的尘埃构成：恒星隐藏其中，并在中心产生强烈的光芒。直向上的一条带是喷流，而其他流出物在盘的上方和下方形成耀斑，并有一条尾巴伸向一侧。 ESA/Webb, NASA & CSA, Tazaki et al.

詹姆斯·韦伯太空望远镜（JWST）2025年2月的天文图展示了行星形成的强大能力。这架太空望远镜最近聚焦于原行星盘HH30。它位于金牛座分子云中的黑暗星云LDN 1551，距离地球约4.5亿光年。

HH30被认为是赫比格-哈罗天体——被新生恒星或原恒星包围的发光区域。这些天体是在这些新生恒星喷出的、称为星风的气体流与高速的气体和尘埃碰撞产生激波时形成的。像HH30这样的原行星盘是新行星最终形成的地方。

根据欧洲空间局（ESA）的说法，HH30对天文学家来说尤为重要。它被认为是边缘盘的标准模型。了解这些盘中发生的事情有助于天文学家研究太空中的尘埃颗粒如何漂移和沉降，并最终形成整个行星。

在这张新图像中，一个国际天文学家团队利用JWST对HH30进行了更详细的研究。他们将JWST的观测与哈勃太空望远镜和阿塔卡马毫米/亚毫米波阵列（ALMA）的观测结合起来。

This new NASA/ESA/CSA James Webb Space Telescope Picture of the Month presents HH 30 in unprecedented resolution. This target is an edge-on protoplanetary disc that is surrounded by jets and a disc wind, and is located in the dark cloud LDN 1551 in the Taurus Molecular Cloud. Herbig-Haro objects, like HH 30, are luminous regions surrounding newborn stars (known as protostars). They form when stellar winds or jets of gas spewing from these newborn stars form shockwaves as they collide with nearby gas and dust at high speeds. HH 30 is of particular interest to astronomers. In fact, the HH 30 disc is considered the prototype of an edge-on disc, thanks to its early discovery with the NASA/ESA Hubble Space Telescope. Discs seen from this view are a unique laboratory to study the settling and drift of dust grains. An international team of astronomers have used Webb to investigate the target in unprecedented detail. By combining Webb’s observations with those from the Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA), the team was able to study the multiwavelength disc appearance of the system and its dynamic structures. These Webb observations were taken as part of the Webb GO programme #2562 (PI F. Ménard, K. Stapelfeldt), which aims to understand how dust evolves in edge-on discs like HH 30. Combined with the keen radio-wavelength eyes of ALMA, these observations show that large dust grains must migrate within the disc and settle in a thin layer. The creation of a narrow, dense layer of dust is an important stage in the process of planet formation. In this dense region, dust grains clump together to form pebbles and eventually planets themselves. In addition to the behaviour of dust grains, the Webb, Hubble, and ALMA images reveal several distinct structures that are nested within one another. Emerging at a 90-degree angle from the narrow central disc is a high-velocity jet of gas. The Webb data showed that clumps of gas within — 原行星盘HH30的近距离图像。图像的一部分被标注为“喷流”（在盘的上方和下方）、“锥形流出”、“可能的螺旋”、“暗带”、“盘”和“尾巴”。左下角的比例尺标记为“300 au”；这比盘本身略宽，但比盘上方的锥形流出要窄。来源：ESA/Webb, NASA & CSA, Tazaki et al. ESA/Webb, NASA & CSA, Tazaki et

ALMA的长波数据追踪了仅几毫米大的尘埃颗粒的位置。JWST的短波红外数据显示了更小的尘埃颗粒的分布——尺寸仅为百万分之一米，或相当于一个细菌的大小。大尘埃颗粒集中在盘的中心，而小尘埃颗粒则分布更广。

这些观测是作为Webb GO项目#2562的一部分进行的。该项目旨在了解像HH30这样的边缘盘中尘埃的演化。与ALMA的射电波段观测结合后，这些观测表明大尘埃颗粒必须首先在盘内迁移，然后沉降成薄层。形成一个狭窄但致密的尘埃层是行星形成过程中的一个重要阶段。这个致密的区域是尘埃颗粒可以聚集在一起形成小石块，并最终形成整个行星的地方。

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除了尘埃颗粒的行为外，新的图像还显示了几个相互嵌套的明显结构。一股高速的气体喷流从狭窄的中心盘中喷出。这股狭窄的喷流被一个更宽的、锥形的流出物包围。一个反射年轻恒星光线的宽阔星云围绕着这个流出物。
总而言之，这表明HH30是一个动态的位置，并且巨大的喷流和微小的尘埃都在构建新行星的过程中发挥着作用。

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