In our nearby stellar neighborhood, a burned-out star is snacking on a fragment of a Pluto-like object. With its unique ultraviolet capability, only NASA’s Hubble Space Telescope could identify that this meal is taking place.
在我们附近的恒星附近，一颗烧毁的恒星正在吞噬一颗类似冥王星的物体的碎片。凭借其独特的紫外线能力，只有美国宇航局的哈勃太空望远镜才能识别出这顿饭正在发生。
The stellar remnant is a white dwarf about half the mass of our Sun, but that is densely packed into a body about the size of Earth. Scientists think the dwarf’s immense gravity pulled in and tore apart an icy Pluto analog from the system’s own version of the Kuiper Belt , an icy ring of debris that encircles our solar system. The findings were reported on September 18 in the Monthly Notices of the Royal Astronomical Society.
恒星残骸是一颗白矮星，质量约为太阳的一半，但它密集地包裹在一个与地球大小相当的天体中。科学家认为，矮星巨大的引力将冰冷的冥王星类似物从该系统自己的柯伊伯带中拉扯并撕裂，柯伊伯带是环绕太阳系的冰冷碎片环。 9 月 18 日，《皇家天文学会月刊》报道了这一发现。
The researchers were able to determine this carnage by analyzing the chemical composition of the doomed object as its pieces fell onto the white dwarf. In particular, they detected “volatiles” — substances with low boiling points — including carbon, sulphur, nitrogen, and a high oxygen content that suggests the strong presence of water.
研究人员通过分析这个注定要失败的物体落到白矮星上时的化学成分，确定了这场大屠杀。特别是，他们检测到了“挥发物”——低沸点物质——包括碳、硫、氮和高氧含量，表明大量存在水。
“We were surprised,” said Snehalata Sahu of the University of Warwick in the United Kingdom. Sahu led the data analysis of a Hubble survey of white dwarfs. “We did not expect to find water or other icy content. This is because the comets and Kuiper Belt-like objects are thrown out of their planetary systems early, as their stars evolve into white dwarfs. But here, we are detecting this very volatile-rich material. This is surprising for astronomers studying white dwarfs as well as exoplanets, planets outside our solar system.”
“我们很惊讶，”英国华威大学的斯尼哈拉塔·萨胡 (Snehalata Sahu) 说。萨胡领导了哈勃白矮星调查的数据分析。 “我们没想到会发现水或其他冰冷的物质。这是因为彗星和柯伊伯带状物体很早就被抛出了它们的行星系统，因为它们的恒星演化成了白矮星。但在这里，我们检测到了这种非常富含挥发性的物质。这对于研究白矮星以及系外行星（太阳系外的行星）的天文学家来说是令人惊讶的。”
Using Hubble’s Cosmic Origins Spectrograph , the team found that the fragments were composed of 64 percent water ice. The fact that they detected so much ice meant that the pieces were part of a very massive object that formed far out in the star system’s icy Kuiper Belt analog. Using Hubble data, scientists calculated that the object was bigger than typical comets and may be a fragment of an exo-Pluto.
使用哈勃的宇宙起源光谱仪，研究小组发现这些碎片由 64% 的水冰组成。事实上，他们检测到如此多的冰，这意味着这些碎片是一个非常巨大的物体的一部分，该物体形成于恒星系统的冰冷柯伊伯带类似物中。利用哈勃数据，科学家计算出该物体比典型的彗星更大，可能是外冥王星的碎片。
They also detected a large fraction of nitrogen – the highest ever detected in white dwarf debris systems. “We know that Pluto’s surface is covered with nitrogen ices,” said Sahu. “We think that the white dwarf accreted fragments of the crust and mantle of a dwarf planet.”
他们还检测到了大量的氮——这是白矮星碎片系统中迄今为止检测到的最高含量。 “我们知道冥王星的表面覆盖着氮冰，”萨胡说。 “我们认为白矮星吸积了矮行星地壳和地幔的碎片。”
Accretion of these volatile-rich objects by white dwarfs is very difficult to detect in visible light. These volatile elements can only be detected with Hubble’s unique ultraviolet light sensitivity. In optical light, the white dwarf would appear ordinary.
白矮星对这些富含挥发物的物体的吸积在可见光下很难被探测到。这些挥发性元素只能通过哈勃独特的紫外光灵敏度来检测。在可见光下，白矮星看起来很普通。
About 260 light-years away, the white dwarf is a relatively close cosmic neighbor. In the past, when it was a Sun-like star, it would have been expected to host planets and an analog to our Kuiper Belt.
白矮星距离我们约260光年，是一个相对较近的宇宙邻居。在过去，当它是一颗类太阳恒星时，人们预计它拥有行星和类似于我们的柯伊伯带的行星。
Billions of years from now, when our Sun burns out and collapses to a white dwarf, Kuiper Belt objects will be pulled in by the stellar remnant’s immense gravity. “These planetesimals will then be disrupted and accreted,” said Sahu. “If an alien observer looks into our solar system in the far future, they might see the same kind of remains we see today around this white dwarf.”
数十亿年后，当我们的太阳燃烧殆尽并坍缩成白矮星时，柯伊伯带天体将被恒星残余物的巨大引力吸引。 “这些星子随后将被破坏和吸积，”萨胡说。 “如果外星观察者在遥远的未来观察我们的太阳系，他们可能会看到我们今天在这颗白矮星周围看到的同样的遗迹。”
The team hopes to use NASA’s James Webb Space Telescope to detect molecular features of volatiles such as water vapor and carbonates by observing this white dwarf in infrared light. By further studying white dwarfs, scientists can better understand the frequency and composition of these volatile-rich accretion events.
研究小组希望利用美国宇航局的詹姆斯·韦伯太空望远镜通过红外光观察这颗白矮星来探测水蒸气和碳酸盐等挥发物的分子特征。通过进一步研究白矮星，科学家可以更好地了解这些富含挥发物的吸积事件的频率和成分。
Sahu is also following the recent discovery of the interstellar comet 3I/ATLAS . She is eager to learn its chemical composition, especially its fraction of water. “These types of studies will help us learn more about planet formation. They can also help us understand how water is delivered to rocky planets,” said Sahu.
Sahu 也在关注最近发现的星际彗星 3I/ATLAS。她渴望了解它的化学成分，尤其是它的水成分。 “这类研究将帮助我们更多地了解行星的形成。它们还可以帮助我们了解水是如何输送到岩石行星的，”萨胡说。
Boris Gänsicke, of the University of Warwick and a visitor at Spain’s Instituto de Astrofisica de Canarias, was the principal investigator of the Hubble program that led to this discovery. “We observed over 500 white dwarfs with Hubble. We’ve already learned so much about the building blocks and fragments of planets, but I’ve been absolutely thrilled that we now identified a system that resembles the objects in the frigid outer edges of our solar system,” said Gänsicke. “Measuring the composition of an exo-Pluto is an important contribution toward our understanding of the formation and evolution of these bodies.”
华威大学的鲍里斯·甘西克 (Boris Gänsicke) 是西班牙加那利天文研究所的访问者，他是导致这一发现的哈勃计划的首席研究员。 “我们用哈勃望远镜观察了 500 多个白矮星。我们已经了解了很多关于行星的组成部分和碎片的知识，但我非常兴奋，因为我们现在发现了一个类似于太阳系寒冷外边缘物体的系统，”Gänsicke 说。 “测量外冥王星的成分对于我们理解这些天体的形成和演化做出了重要贡献。”
The Hubble Space Telescope has been operating for more than three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
哈勃太空望远镜已经运行了三十多年，并不断做出突破性的发现，塑造我们对宇宙的基本理解。哈勃望远镜是 NASA 和 ESA（欧洲航天局）之间的国际合作项目。美国宇航局位于马里兰州格林贝尔特的戈达德太空飞行中心负责管理望远镜和任务操作。总部位于丹佛的洛克希德·马丁航天公司也支持戈达德的任务运营。位于巴尔的摩的太空望远镜科学研究所由天文学研究大学协会运营，为美国宇航局进行哈勃科学操作。
To learn more about Hubble, visit: https://science.nasa.gov/hubble
要了解有关哈勃的更多信息，请访问：https://science.nasa.gov/hubble