激光雕刻机 | 2023-05-27
本文摘要:Astronomers said on Wednesday that they had discovered a lost generation of monster stars that ushered light into the universe after the Big Bang and jump-started the creation of the elements needed for planets and life before disappearing forever.天文学家在周三回应,他们找到了下落不明的一代巨型恒星,是它们在宇宙大爆炸之后将光照进宇宙,并在总有一天消失之前,瞬间启动了星球及生命所必须的所有元素的建构。

Astronomers said on Wednesday that they had discovered a lost generation of monster stars that ushered light into the universe after the Big Bang and jump-started the creation of the elements needed for planets and life before disappearing forever.天文学家在周三回应,他们找到了下落不明的一代巨型恒星,是它们在宇宙大爆炸之后将光照进宇宙,并在总有一天消失之前,瞬间启动了星球及生命所必须的所有元素的建构。Modern-day stars like our sun have a healthy mix of heavy elements, known as metals, but in the aftermath of the Big Bang only hydrogen, helium and small traces of lithium were available to make the first stars.太阳等现代恒星享有大量重元素,也就是金属元素,但在宇宙大爆炸之后,包含第一代恒星的元素只有氢、氦和少量锂。Such stars could have been hundreds or thousands of times as massive as the sun, according to calculations, burning brightly and dying quickly, only 200 million years after the universe began. Their explosions would have spewed into space the elements that started the chain of thermonuclear reactions by which subsequent generations of stars have gradually enriched the cosmos with elements like oxygen, carbon and iron.根据计算出来,此类恒星的质量有可能是太阳质量的数百或数千倍,这些构成于宇宙大爆炸后2亿年的恒星激烈自燃,很快消失。它们的发生爆炸应当向太空喷气了打开一系列热核反应的元素,先前的几代恒星通过热核反应渐渐为宇宙加添氧、碳、铁等元素。

Spotting the older stars in action is one of the prime missions of the James Webb Space Telescope, to be launched by NASA in 2018. The discovery of such stars “would be wonderful,” James Peebles, a Princeton professor and one of the fathers of modern cosmology, said recently.找寻有活动的古老恒星是美国国家航空航天局(NASA)詹姆斯·韦伯太空望远镜的主要任务之一,该望远镜将于2018年升空。普林斯顿大学(Princeton)教授詹姆斯·佩布莱斯(James Peebles)最近回应,找到此类恒星“不会是一件十分动人的事情”,他是现代宇宙学奠基人之一。Now, in a paper to be published in The Astrophysical Journal, an international crew of astronomers led by David Sobral of the University of Lisbon, in Portugal, and the Leiden Observatory, in the Netherlands, said they had spotted the signature of these first-generation stars in a recently discovered galaxy that existed when the universe was only about 800 million years old. Its light has been traveling to us for 12.9 billion years, while succeeding generations of stars have worked their magic to make the universe interesting.在《天文物理期刊》(The Astrophysical Journal)将要刊出的一篇论文中,由葡萄牙里斯本大学(University of Lisbon)的戴维·索夫拉尔(David Sobral)、荷兰莱顿天文台(Leiden Observatory)率领的国际天文学家小组回应,他们在最近找到的星系中寻找了第一代恒星的辨识标志,该星系在宇宙只有约8亿年历史的时候就经常出现了。


该星系收到的光用了129亿年才抵达地球,在此期间,先前的几代恒星施展魔法,让宇宙显得有意思。The galaxy, known as CR7, is three times as luminous as any previously found from that time, the authors said. Within it is a bright blue cloud that seems to contain only hydrogen and helium.作者回应,这个被称作CR7的星系的亮度是之前找到的同期星系的亮度的三倍。

该星系里面是一个或许只包括氢和氦的亮蓝色星云。In an email, Dr. Sobral called this the first direct evidence of the stars “that ultimately allowed us all to be here by fabricating heavy elements and changing the composition of the universe.”索夫拉尔在邮件中称之为,这是第一个直接证明这些恒星“通过建构重元素,转变宇宙的包含,最后使得我们以求不存在”的证据。In a statement from the European Southern Observatory, he said, “It doesn’t really get any more exciting than this.”在欧洲南方天文台(European Southern Observatory)公开发表的声明中,他回应,“没什么比这个更加令人激动的了。”Garth Illingworth, an astronomer at the University of California, Santa Cruz, and a veteran of the search for early galaxies, pointed out, however, that these stars were appearing far later in cosmic history than theory had predicted.但加州大学圣克鲁斯分校(University of California, Santa Cruz)天文学家加思·伊林沃思(Garth Illingworth)认为,这些恒星在宇宙历史中经常出现的时间比理论预测的时间要晚得多。

伊林沃思在找寻早期星系方面有非常丰富的经验。Dr. Sobral and his colleagues were using the Very Large Telescope of the Southern Observatory in Chile and the W. M. Keck Observatory in Hawaii, among other big telescopes, to build on an earlier search for glowing clouds of hydrogen that might represent very early galaxies. Galaxy CR7 — short for Cosmos Redshift 7, after the method by which distant objects in the universe are dated — stood out.索夫拉尔和他的同事利用南方天文台在智利设置的甚大望远镜(Very Large Telescope)、夏威夷的W·M·凯克天文台(W. M. Keck Observatory)及其他大型望远镜,之后之前找寻由氢构成的闪烁星云的工作,这些星云有可能代表着早期的星系。

他们找到了GR7星系——宇宙白后移7号(Cosmos Redshift 7)的简写,故名于追溯到宇宙中很远物体所用于的方法。In an expanding universe, the farther away or back in time an object is, the faster it is receding, which causes the wavelength of light from it to lengthen, the way the pitch of a siren sounds lower after it passes. In astronomy, this lengthening is known as redshifting.在大大收缩的宇宙中,一个物体就越久远,消失的速度就越好,这造成物体收到的光的波长逆宽,就像救护车火光经过后,警报器的音高不会渐渐减少。

在天文学上,这种缩短被称作白后移。The galaxy’s name, Dr. Sobral said, was also inspired by the great Portuguese soccer player Cristiano Ronaldo, a.k.a. CR7.索夫拉尔回应,该星系的名称——CR7还受到葡萄牙杰出的足球运动员克里斯蒂亚诺·罗纳尔多(Cristiano Ronaldo)的灵感。


As in much of astronomy, the nomenclature of these star generations is awkwardly rooted in history and Earth-centered. Modern stars like the sun, with healthy abundances of so-called metals (anything heavier than helium), are now called Population I, mainly because they were the first known. They mostly inhabit the spiral arms and younger parts of galaxies like the Milky Way.在天文学的主要领域,各代恒星的命名都失望地遵守历史,是以地球为中心的。太阳等现代恒星享有充足的金属元素(比氦轻的物质),它们现在被称作第一星族(Population I),主要是因为它们是首批被找到的恒星。它们主要坐落于银河系(Milky Way)等星系的旋臂和年长星团中。

In the middle of the 20th century, however, the astronomer Walter Baade noticed that the stars in older parts of the galaxy, like its core or globular clusters, are older and have fewer metals. He called them Population II.但在20世纪中叶,天文学家瓦尔特·巴德(Walter Baade)注意到,该星系的古老星团——比如它的核心星团或球状星团——中的恒星年代更加久远,金属元素更加较少。他称作第二星族(Population II)。The advent of the Big Bang theory of the origin of the universe forced astronomers to realize that the first stars must have had no metals at all; those are known as Population III.有关宇宙起源的大爆炸理论的经常出现,被迫天文学家认识到,第一代恒星认同不包括金属元素;它们被称作第三星族(Population III)。

Stars of both Population II and Population III are probably present in CR7, Dr. Sobral and his team report. While the blue cloud is metal-free, according to spectral measurements, the color of the rest of the galaxy is consistent with more evolved stars making up most of its mass. This suggests, they write, that the Population III stars there are late bloomers of a sort, forming from leftover clouds of pristine material as the galaxy was sending out its light 12.9 billion years ago.索夫拉尔和他的团队报告称之为,CR7星系中有可能不存在第二星族和第三星族的恒星。虽然根据光谱测量,这个蓝色星云不包括金属元素,但该星系剩下部分的颜色与进化程度较高的、包含其大部分质量的恒星完全一致。他们写到,这解释该星系中的第三星族恒星构成较早,由该星系129亿年前收到光线时的崭新物质的瓦解星云发展而出。

The only alternative explanation, Dr. Sobral said, is something so spectacular and unlikely that astronomers do not know if it has ever happened, namely a primordial cloud bypassing the star stage and collapsing directly into a black hole. That, he noted, is impossible to rule out because nobody really knows what it should look like.索夫拉尔回应,除此之外的唯一说明是,再次发生了一些难以置信的、意想不到的事,天文学家还不告诉这种事否再次发生过,那就是完整星云跨过恒星阶段,必要塌缩为黑洞。他认为,无法回避这种可能性,因为没有人知道告诉它看起来是什么样子。

Further observations with the Hubble Space Telescope and the James Webb could help resolve the issue.利用哈勃太空望远镜和詹姆斯·韦伯太空望远镜更进一步仔细观察也许有助这个问题的解决问题。