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Astronomers find the corpse of a galaxy early in the universe
Galaxies form stars from their clouds of dust and gas. But a galaxy spotted by the James Webb Space Telescope (JWST) hasn’t formed any stars for 13 billion years.
The galaxy, called JADES-GS-z7-01-QU, and its quiet behavior was described in a study posted last year as a preprint on arXiv and then published March 6 in Nature.
“Everything seems to happen faster and more dramatically in the early universe, and that might include galaxies moving from a star-forming phase to dormant or quenched,” said Tobias Looser, a researcher at the Kavli Institute for Cosmology at the University of Cambridge and the study’s first author, in a press release.
Star formation
The galaxy’s name is derived from the JWST Advanced Deep Galactic Survey (JADES), the project that observed it.
Members of the team found that the galaxy most likely had a quick burst of star formation that lasted between 30 million to 90 million years. But it seems to have stopped developing stars just 10 million to 20 million years earlier than the snapshot in time in which we observe it. Its light has taken over 13 billion years to reach us, so JWST sees it as it existed just 700 million years after the Big Bang, making it the oldest “dead” galaxy yet found.
A galaxy can stop forming stars when its central supermassive black holes pulls in the interstellar reservoir of dust from which it create new stars. A galaxy can also use up its dusty resources by forming stars too quickly, accidentally starve itself, and cut off all new star formation. The team is not sure if what they observed with JWST was caused by either of these scenarios. But observing older galaxies helps astronomers piece together how galaxies evolve and how stars form, and use the data to create more accurate models.
Galaxies that appear to have suddenly stopped forming new stars are not new to astronomers. In fact, by the time the universe was 3 billion years old, about half of its massive galaxies had stopped its star formation. And observations from the Hubble Space Telescope and ESO’s Very Large Telescope indicate that in dead galaxies, star formation stops at its core and fizzles from the inside out — galaxies like the elliptical galaxy IC 2006 only form stars on their fringes edges of their disk.
So why do galaxies forced to shut down their star factories? It may be because something is preventing gas from flowing into the galaxies to replenish it, per a study in Nature from 2021. It may also be that collisions and mergers of galaxies play a role. A study in the Astrophysical Journal Letters found that in galaxies that merged, their gas was heated or stripped to the point where it couldn’t form star nurseries after an initial burst. (Hot gas can’t easily form stars as it won’t collapse as readily as cold gas.)
The JADES team hopes to provide some clarity. “We’re looking for other galaxies like this one in the early universe, which will help us place some constraints on how and why galaxies stop forming new stars,” said Francesco D’Eugenio, study co-author and researcher at the Kavli Institute for Cosmology, in a statement. “It could be the case that galaxies in the early universe ‘die’ and then burst back to life — we’ll need more observations to help us figure that out.”
注释：
dormant: adj
表示"休眠的；睡眠的；静止的"，means "in a condition of biological rest or suspended animation"，如：Many living things are dormant in winter. 很多生物到了冬季都休眠。
quench: v
表示"解渴"，means "put out; damp down a fire, flames, etc."，如：Water will quench a fire. 水可以灭火。
replenish: v
表示" 补充"，means "fill something that had previously been emptied"，如：We need to replenish our stocks of coal. 我们需要再次补充煤的储备。
中文简要说明：
天文学家发现了宇宙早期的一个星系（Galaxy）残骸，也是目前已知最古老的「死亡」星系，这一个研究发现有助于解开星系的一个谜团，即为何有些星系会突然停止制造新恒星的原因，这项研究本周已经发表在权威期刊《自然》（Nature）上。
据《天文学》（Astronomy）报导，恒星从星系里的尘埃和气体云中形成。而韦伯太空望远镜（JWST）发现了一个星系长时间没有形成任何恒星。这个星系被称为JADES-GS-z7-01-QU，其寂静的行为在去年发表在arXiv上的一项研究中进行了描述，并发表于《自然》期刊。
剑桥大学科维理宇宙学研究所（Kavli Institute for Cosmology）的研究员卢瑟（Tobias Looser）在新闻发布会上表示：「在早期宇宙中，似乎一切都发生得更快、更戏剧性，这可能还包括星系从形成（制造）恒星的阶段转变为休眠或停滞状态。」
该团队成员发现，JADES-GS-z7-01-QU星系最有可能经历了一次持续了3000万至9000万年左右的快速恒星形成爆发时期。
它似乎在我们观测到的时间点之前仅仅10至20万年停止了恒星形成。但由于它散发出来的光，走了超过130亿年才抵达我们，所以JWST将其视为大爆炸后仅仅7亿岁的星系，这使其成为迄今为止发现的最古老的「死亡」星系。
关于一个星系停止形成新的恒星的原因，当其中央超大质量黑洞，把从星系中央区域的星际尘埃全吸黑洞里面。或者，一个星系也可能形成恒星太快，意外的将中央区域星际尘埃全用光，使得自己饿死，导致新的恒星无法形成。
该团队目前不确定，他们在JWST观察到的是由上述2种情况中的哪一种引起的，但观察老年星系有助于天文学家了解星系的演变和恒星的形成，并使用数据创建更准确的模型。
留言微信公众号《自然学英语LearnNaturally》，可咨询更多！
Astronomers find the corpse of a galaxy early in the universe
Galaxies form stars from their clouds of dust and gas. But a galaxy spotted by the James Webb Space Telescope (JWST) hasn’t formed any stars for 13 billion years.
The galaxy, called JADES-GS-z7-01-QU, and its quiet behavior was described in a study posted last year as a preprint on arXiv and then published March 6 in Nature.
“Everything seems to happen faster and more dramatically in the early universe, and that might include galaxies moving from a star-forming phase to dormant or quenched,” said Tobias Looser, a researcher at the Kavli Institute for Cosmology at the University of Cambridge and the study’s first author, in a press release.
Star formation
The galaxy’s name is derived from the JWST Advanced Deep Galactic Survey (JADES), the project that observed it.
Members of the team found that the galaxy most likely had a quick burst of star formation that lasted between 30 million to 90 million years. But it seems to have stopped developing stars just 10 million to 20 million years earlier than the snapshot in time in which we observe it. Its light has taken over 13 billion years to reach us, so JWST sees it as it existed just 700 million years after the Big Bang, making it the oldest “dead” galaxy yet found.
A galaxy can stop forming stars when its central supermassive black holes pulls in the interstellar reservoir of dust from which it create new stars. A galaxy can also use up its dusty resources by forming stars too quickly, accidentally starve itself, and cut off all new star formation. The team is not sure if what they observed with JWST was caused by either of these scenarios. But observing older galaxies helps astronomers piece together how galaxies evolve and how stars form, and use the data to create more accurate models.
Galaxies that appear to have suddenly stopped forming new stars are not new to astronomers. In fact, by the time the universe was 3 billion years old, about half of its massive galaxies had stopped its star formation. And observations from the Hubble Space Telescope and ESO’s Very Large Telescope indicate that in dead galaxies, star formation stops at its core and fizzles from the inside out — galaxies like the elliptical galaxy IC 2006 only form stars on their fringes edges of their disk.
So why do galaxies forced to shut down their star factories? It may be because something is preventing gas from flowing into the galaxies to replenish it, per a study in Nature from 2021. It may also be that collisions and mergers of galaxies play a role. A study in the Astrophysical Journal Letters found that in galaxies that merged, their gas was heated or stripped to the point where it couldn’t form star nurseries after an initial burst. (Hot gas can’t easily form stars as it won’t collapse as readily as cold gas.)
The JADES team hopes to provide some clarity. “We’re looking for other galaxies like this one in the early universe, which will help us place some constraints on how and why galaxies stop forming new stars,” said Francesco D’Eugenio, study co-author and researcher at the Kavli Institute for Cosmology, in a statement. “It could be the case that galaxies in the early universe ‘die’ and then burst back to life — we’ll need more observations to help us figure that out.”
注释：
dormant: adj
表示"休眠的；睡眠的；静止的"，means "in a condition of biological rest or suspended animation"，如：Many living things are dormant in winter. 很多生物到了冬季都休眠。
quench: v
表示"解渴"，means "put out; damp down a fire, flames, etc."，如：Water will quench a fire. 水可以灭火。
replenish: v
表示" 补充"，means "fill something that had previously been emptied"，如：We need to replenish our stocks of coal. 我们需要再次补充煤的储备。
中文简要说明：
天文学家发现了宇宙早期的一个星系（Galaxy）残骸，也是目前已知最古老的「死亡」星系，这一个研究发现有助于解开星系的一个谜团，即为何有些星系会突然停止制造新恒星的原因，这项研究本周已经发表在权威期刊《自然》（Nature）上。
据《天文学》（Astronomy）报导，恒星从星系里的尘埃和气体云中形成。而韦伯太空望远镜（JWST）发现了一个星系长时间没有形成任何恒星。这个星系被称为JADES-GS-z7-01-QU，其寂静的行为在去年发表在arXiv上的一项研究中进行了描述，并发表于《自然》期刊。
剑桥大学科维理宇宙学研究所（Kavli Institute for Cosmology）的研究员卢瑟（Tobias Looser）在新闻发布会上表示：「在早期宇宙中，似乎一切都发生得更快、更戏剧性，这可能还包括星系从形成（制造）恒星的阶段转变为休眠或停滞状态。」
该团队成员发现，JADES-GS-z7-01-QU星系最有可能经历了一次持续了3000万至9000万年左右的快速恒星形成爆发时期。
它似乎在我们观测到的时间点之前仅仅10至20万年停止了恒星形成。但由于它散发出来的光，走了超过130亿年才抵达我们，所以JWST将其视为大爆炸后仅仅7亿岁的星系，这使其成为迄今为止发现的最古老的「死亡」星系。
关于一个星系停止形成新的恒星的原因，当其中央超大质量黑洞，把从星系中央区域的星际尘埃全吸黑洞里面。或者，一个星系也可能形成恒星太快，意外的将中央区域星际尘埃全用光，使得自己饿死，导致新的恒星无法形成。
该团队目前不确定，他们在JWST观察到的是由上述2种情况中的哪一种引起的，但观察老年星系有助于天文学家了解星系的演变和恒星的形成，并使用数据创建更准确的模型。
留言微信公众号《自然学英语LearnNaturally》，可咨询更多！