华盛顿，10月6日：在古代神话中，凤凰是一种神奇的鸟儿，它具有生死循环的模式，毁于烈焰后从灰烬中重生。天文学家们现在发现了一个确实可以称为凤凰行星的世界。
WASHINGTON, Oct 6 : In ancient mythology, the phoenix was a miraculous bird with a cyclical pattern of life and death, perishing in flames only to rise again from the ashes. Astronomers have now found a world that rightly can be called a phoenix planet.
研究人员表示，这颗系外行星（即绕远于我们太阳系之外恒星运行的行星）似乎诞生于一颗略大于太阳的恒星在死亡过程中喷射到太空中的物质中，并现在绕着一颗高度压缩的恒星残骸——白矮星运行。
Researchers said this exoplanet, as planets beyond our solar system are called, appears to have been born from material expelled into space during the death throes of a star a bit bigger than the sun, and now orbits the highly compact stellar remnant that was left behind, called a white dwarf.
它被归类为第二代行星，这意味着它不是像地球和其他第一代行星那样从围绕新生恒星的旋转物质盘中形成的，而是从一颗注定要毁灭的恒星的残留物中形成的。"这是第一颗绕白矮星形成的行星例子，"来自英国华威大学天体物理学博士研究生、也是本周发表在《自然天文学》杂上的研究论文主要作者杰米·威廉斯表示。
It is classified as a second-generation planet, meaning it did not form from the swirling disk of material surrounding a newborn star, as Earth and other first-generation planets did, but rather from the leftovers of a doomed star. "This is the first example of a planet forming around a white dwarf," said Jamie Williams, a doctoral student in astrophysics at the University of Warwick in England and lead author of the study published this week in the journal Nature Astronomy.
这颗白矮星位于距离地球约250光年远的海豚座附近。光年是光在一年中行进的距离，约5.9万亿英里（9.5万亿公里）。
The white dwarf is located about 250 light-years from Earth, near the constellation Cetus. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).
这颗行星可能是一颗气体巨行星，质量或许略大于我们太阳系中最大的行星——木星。它每隔4.4天绕白矮星运行一次，且距离仅为地球与太阳之间的距离的4%。它如此靠近，以至于那颗炽热的白矮星发出的强烈紫外线辐射正在导致该行星的外大气层蒸发，其中一部分随后坠入白矮星中。
The planet is a gas giant perhaps slightly more massive than Jupiter, our solar system's largest planet. It orbits the white dwarf every 4.4 days at only 4 per cent the distance between Earth and the sun. It is so close that the blazingly hot white dwarf's extreme ultraviolet radiation is causing the planet's outer atmosphere to evaporate, with a portion then falling into the white dwarf.
该行星的化学成分指向其第二代起源。它富含铌、铜和锌，这些正是某些在死亡过程中膨胀时会抛弃的恒星所释放的元素，表明该行星是从围绕这颗恒星尸体的喷射物质盘中形成的。
The planet's chemical pattern points to its second-generation origin. It is rich in niobium, copper and zinc, the type of elements that certain dying stars cast off when they expand in their death throes, indicating the planet formed from a disk of this expelled material that surrounded the stellar corpse.
“在神话中，凤凰能从自己的灰烬中重生。对于这颗行星而言，它则是在其母恒星消亡后的灰烬中诞生，整个行星系统也因此获得新生。所谓‘第二代行星’，指的是那些在母恒星死亡后形成的行星——在本例中，就是在母恒星变成白矮星之后形成的。”威廉姆斯说道。
"In myths, a phoenix is born again from its own ashes. In the case of this planet, it is born again from the ashes of its dying host star, and therefore the planetary system is reborn. A second-generation planet is defined as one born after its host star dies — in this case after it has become a white dwarf," Williams said.
研究人员利用了哈勃望远镜、TESS望远镜以及FUSE望远镜获取的数据，并希望借助詹姆斯·韦伯太空望远镜来验证他们的结论。
The researchers used data from the orbiting Hubble, TESS and FUSE telescopes, and hope to use the James Webb Space Telescope to confirm their conclusions.
此前，天文学家已经发现了少量可能属于第二代行星的天体，它们围绕着脉冲星运行。脉冲星是一种极为罕见的中子星，也属于恒星残骸的一种。
A small number of potential second-generation planets previously have been identified orbiting pulsars, a rare type of neutron star, another type of stellar remnant.
“白矮星的数量远多于脉冲星，银河系中超过95%的恒星最终都会演化为白矮星。因此，围绕白矮星运转的第二代行星数量理应远多于围绕脉冲星运转的行星。”威廉姆斯解释道。
"White dwarfs are much more common than pulsars, and over 95 per cent of stars in the Milky Way will evolve to become a white dwarf. Therefore, there would be many more second-generation planets around white dwarfs than around pulsars," Williams said.
虽然这颗新发现的行星并不适合生命生存，但其他第二代行星或许具备宜居条件。
While the newly discovered planet would be inhospitable for life, another second-generation planet potentially could be habitable.
“如果一颗气态巨行星能在白矮星周围形成，那么岩石行星也有可能随之诞生。白矮星的温度会随时间呈可预测的规律下降，且降温速度会逐渐变慢。因此，若某颗第二代岩石行星恰好位于距离白矮星较近的位置，它便有可能在宜居带内存在数十亿年之久。”威廉姆斯说道。
"If a gas giant formed around a white dwarf, then a rocky planet could form, too. White dwarfs cool predictably over time and as they get cooler, their cooling slows. So if a second-generation rocky planet formed close enough to the white dwarf then it could remain in the habitable zone for billions of years," Williams said.
红矮星与棕矮星在同一期刊上发表的另一项研究，则描述了一个位于地球约300至500光年外、金牛座区域内的奇特天体现象。
A RED DWARF AND A BROWN DWARF A second study published in the same journal describes another exotic celestial phenomenon roughly 300 to 500 light-years from Earth in the constellation Taurus.
研究人员借助位于加利福尼亚州帕洛玛天文台的兹威基瞬变设施，发现了一颗质量仅为太阳8%的红矮星，它正与一颗棕矮星保持着极近的轨道关系。棕矮星的质量约为木星的30倍，相当于该红矮星质量的三分之一；它既达不到成为恒星的标准，又比普通行星要大得多。
Researchers used the Zwicky Transient Facility at Palomar Observatory in California to discover a red dwarf star about 8 per cent of the mass of the sun in a tight orbit with a brown dwarf, an object too small to be a star and too big to be a planet. The brown dwarf is about 30 times the mass of Jupiter and a third of the mass of the star.
这两颗天体每87分钟绕彼此旋转一圈，它们之间的距离略大于地球与月球距离的一半。这颗恒星的引力似乎正在从棕矮星上吸走物质。研究人员在恒星表面发现了一个热点区域，这些物质似乎正是在此处沉积下来。
These two companions orbit each other every 87 minutes at slightly more than half the distance between Earth and the moon, and the star's gravitational pull appears to be siphoning material from the brown dwarf. The researchers detected a hot spot on the star's surface where this material appears to be landing.
“这是人类首次观测到此类现象，”麻省理工学院天体物理学专业研究生、该研究的主要作者亚伦·豪斯霍尔德说道。
"This is the first observed example of this phenomenon," said Aaron Householder, a Massachusetts Institute of Technology graduate student in astrophysics and lead author of the study.
“这两颗天体距离极其接近，以至于它们绕行一周的轨道长度都还比不上太阳的直径，”豪斯霍尔德补充道。
"The two objects are so close together that the entire orbit would fit inside the sun," Householder said.