When the hydrogen used as fuel vanishes, and fusion slows, gravity causes the star to collapse in on itself.
当作为燃料的氢消失，且聚变过程减缓时，重力就导致恒星向内坍缩。
Red giants exist for only a short time—perhaps just a billion years compared with the ten billion the same star may already have spent burning hydrogen like our own sun.
红巨星只在短期内存在——可能只有十亿年，相比起来，像太阳这样的恒星将在百亿年中持续燃烧它们的氢。
When a star similar to the sun fuses most of its hydrogen into helium, then the helium into carbon, the star becomes unstable and puffs out into a red giant.
当一颗类日恒星大部分的氢聚变为氦，氦又聚变成碳的时候，它就变得不再稳定，而膨胀成一颗红巨星。
Reddish hydrogen emission regions, called HII regions, are the regions of intense star formation seen to lie mainly along M51's bright spiral arms.
红色的氢发射区域，称为HII区域，是激烈的恒星形成区，主要沿着M51明亮的旋臂可见。
Metallicity is a measure of the relative abundance in a star of elements other than hydrogen and helium.
金属丰度是对恒星内除氢和氦之外元素的相对丰度的度量(天文学中比氦重的元素都叫金属。——译者注)。
As the star condenses and compacts it heats up even further, burning the last of its hydrogen and causing the star's outer layers to expand outward.
恒星聚缩时甚至继续升温，这个过程燃尽了残存的氢，并导致恒星外层向外膨胀。
They would have been almost pure hydrogen — the primary ingredient of thermonuclear fusion, which makes a star shine.
它们可能曾经几乎完全是由氢元素构成的，氢元素是热核融合的主要原料，正是这种反应让星星放出光芒。
HIP 13044b's existence is bit of a mystery too, since it is the first planet of any origin found around a star lacking resources beyond hydrogen and helium.
HIP 13044b的存在还是有点令人费解的。因为它是第一颗被发现起源于恒星周围却除了氢和氦之外缺乏其他金属的行星。
The star used to be like the sun, a "main sequence" star that burns hydrogen by nuclear fusion, producing helium.
这颗恒星曾和太阳一样，是颗“主序星”(“main sequence”)。它通过核聚变燃烧氢，从而产生氦。
That's the class of star that Naslim and Jeffery were studying, hoping to ferret out clues as to why this category of star has so much less hydrogen on their surfaces than other similar stars.
那就是Naslim和Jeffery正在研究的恒星类型，希望找到这颗恒星比其他相似的恒星的表面少了许多氢元素的原因。
These are silhouetted against glowing newborn star clusters and iridescent pink clouds of hydrogen, the existence of which indicates ongoing star formation.
我们可以看到充满活力的新生星团轮廓和虹彩粉红的氢气云，这些都预示着正在发生恒星形成过程。
The two orange dots are the cores of the old galaxies. Pink is hydrogen; blue the star-forming regions.
两个橙色的亮点是老星系的核心部位，粉红色的东西是氢，蓝色的区域有恒星正在形成。
Ionized molecular hydrogen can be seen evaporating from the tips of these star-forming columns of gas and dust, under pressure of ultraviolet light from the nebula's central blue giant stars.
在来自星云中心蓝巨星紫外线辐射的压力下，这些由气体和尘埃组成的恒星形成区域尖端的电离氢分子将不复存在。
A star is made when a huge cloud of mostly hydrogen gas collapses.
当一个主要由氢气组成的星气团崩解时，一颗星星就形成了。
The greater the mass of such a star, the more quickly it will use its hydrogen fuel and the shorter it stays on the main sequence.
恒星的质量越大，它消耗氢燃料的速度也就越快，它在主序中停留的时间也就越短。
He saw that the constituent parts were being separated, with hydrogen gas falling into the star while water vapour remained farther out and the dust was farther out still.
他发现组成部分正在分离——氢气落入恒星里面，而水蒸汽留在外围，尘埃还在更外面。
Unhappily, Zee Prime began collecting interstellar hydrogen out of which to build a small star of his own.
泽·普赖姆闷闷不乐地开始收集星际空间的氢，用来造一颗自己的小恒星。
It begins with Maarten Schmidt who hypothesized that star formation rate (SFR) was related to the surface density of atomic hydrogen gas in the cloud.
最早是MaartenSchmidt猜测恒星形成率(SFR)与云层中氢原子气体密度有关。
But most of the hydrogen in the Universe isn't in some exciting, star-forming region.
可惜，宇宙中只有很少一部分氢原子存在于引人注目的恒星形成区。
Every 20 years or so the red giant star dumps enough hydrogen gas onto its companion White Dwarf star to set off a brilliant thermonuclear explosion on the White Dwarf's surface.
大约每过20年红巨星向它的白矮伴星上输出足够的氢气在白矮星表面产生一次耀眼的热核爆炸。
A small nugget of cold molecular hydrogen, called a bok globule, is silhouetted against the star cluster.
一个叫“博克球状体”的冷氢“小金块”逆着该星团形成剪影。
As it burned through its supply of hydrogen, the star would have swelled to become a so-called red giant, tens, or even hundreds of times its original size.
当燃尽了氢储备后，这颗恒星膨胀成了一颗所谓的红巨星，是原来尺寸大小的几十倍甚至几百倍。
This stirs up hydrogen fuel and causes the growing star to undergo nuclear fusion at a faster rate.
这煽起氢燃料及原因进行不断增长的星核融合的速度在加快。
It has become what astronomers call a subgiant, or a star that has exhausted all of its hydrogen fuel in the core and is on its way to becoming a red giant.
它已经变成了天文学家所谓的‘亚巨星’，也就是说成为已经耗尽了核心中氢燃料的恒星，并且正在变成红巨星。
It has become what astronomers call a subgiant, or a star that has exhausted all of its hydrogen fuel in the core and is on its way to becoming a red giant.
它已经变成了天文学家所谓的‘亚巨星’，也就是说成为已经耗尽了核心中氢燃料的恒星，并且正在变成红巨星。
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