拿好你的望远镜 因为塔比星刚刚又变暗了！
Hold on to your telescopes, because Tabby’s star just dimmed again!
两年前 天文学家发现了一颗大约1300光年外的恒星
Two years ago, astronomers spotted a star almost 1300 light years away
命名为 KIC 8462852 又称塔比星
called KIC 8462852, nicknamed Tabby’s star
命名来源于它的主要研究者塔贝萨·波雅江 的名字
after the lead researcher, Tabetha Boyaijan.
被发现以来 这颗恒星就因它怪异的亮度变暗令研究者相当困惑
And it’s been baffling them with its weird drops in brightness ever since.
一直以来我们都能观测到恒星像这样变暗 当另一颗行星从它和地球间经过的时候
We see stars dim like this all the time when a planet passes in between them
实际上很多系外星体都是通过这种方法发现的
and the Earth, which is actually how we find lots of exoplanets.
但是塔比星非周期性地变暗幅度超过20%
But Tabby’s star randomly becomes up to 20 percent dimmer,
这种过于极端且无法预测的变暗不可能是围绕它作轨道运行的行星造成的
which is way too extreme and unpredictable to be caused by a planet orbiting it.
并且塔比星似乎变得越来越暗
And it seems to be getting dimmer over time.
就像有什么东西绕着这颗星
It seems like there has to be something orbiting the star,
然而对于这些神秘的数据我们仍然没有一个较好的解释
but we still don’t have a great explanation for these mysterious data.
因此天文学家们一直在等待着观测更多的亮度变化现象
So astronomers have been waiting to observe more dips in brightness
来帮助他们作出假说
to help develop their hypotheses.
就在上周 这种变化终于又发生了
And last weekend, it finally happened again!
许多天文学家记录了塔比星的再次变暗
Multiple astronomers reported that Tabby’s star was dimming,
这个消息使得全世界研究者的目光纷纷拿起了望远镜
which sent researchers around the world running for their telescopes.
这是我们第一次能够在这颗星开始变暗时立即展开观测
This was the first time we were able to see the star dim right from the beginning
并且通过许多种不同型号的望远镜收集数据
in real time, and gather data with lots of different kinds of telescopes.
因此这是我们目前最好的机会去尝试分析经过塔比星的
So it’s also our best chance yet to try and analyze what kind of material
究竟是什么物质
might be passing in front of it.
截止到我们录制这个视频的周三
As of Wednesday when we filmed this,
还没有发布正式的公告
there haven’t been any major announcements.
但是现在有很多基于之前数据的假定
But there are a lot of hypotheses from older data
这些假定有被支持的也有被推翻的
that could be supported or disproved.
例如 你可能还记得那篇推测这种离奇现象
Like, you might remember the paper that suggested this weirdness
是由巨大的外星超级建筑造成的文章
could be caused by huge alien megastructures,
然而 也有很多自然原因可以解释这种现象
but there are plenty of natural explanations too,
例如一片破碎的彗星群
like a bunch of crumbling comets.
这一观点上个月发表在
One idea published last month in the
《英国皇家天文学月刊》上
Monthly Notices of the Royal Astronomical Society
猜测塔比星可能正在吞噬一颗星体
suggests that Tabby’s star might be digesting a planet!
研究人员提出几百或上千年前
The researchers proposed that, anywhere from a few hundred to thousands
一颗星体撞上了塔比星 然后迅速释放出大量能量
of years ago, a planet collided with the star, and released a burst of energy.
这使塔比星在一段时间内变得很亮
That could’ve caused the star to get brighter for a while,
因此目前观察到的变暗只是它恢复到正常的亮度
so all the progressive dimming is actually just the star returning to normal,
而那些非周期性变暗是由遗留的碎片造成的
and the random dips are from leftover debris.
另一个去年十二月发表在《物理评论快报》上的假说认为
Another hypothesis, published last December in the Physical Review Letters,
这颗恒星内部可能发生了我们不清楚的变化
suggests that an unknown process inside the star
导致其磁极出现随机反复翻转
is causing its magnetic poles to randomly flip back and forth,
因此它的亮度会发生波动
which makes its light fluctuate.
大部分解释听起来很合理
Most of these explanations sound reasonable,
但是我们仍然需要更多数据来解开塔比星的秘密
but we need more data to really solve the mystery of Tabby’s star.
最终答案也可能是我们现在尚没有获得证据的！
The answer could even be something we don’t have evidence for yet!
但仍然不太可能是外星人！
But it’s still probably not aliens.
很遗憾！
Sorry!
现在塔比星可能算很异常的一颗恒星
Now, Tabby’s star might be pretty weird,
但宇宙中还有很多奇怪的星球
but the universe also has its fair share of strange planets.
有下玻璃雨的系外星球 拥有热冰的
There are exoplanets where it rains glass, worlds with hot ice,
最近发现的KELY-11b号星球 一个巨大的气体星球
and now there’s KELT-11b, a recently-discovered gas giant
它的密度和泡沫聚苯乙烯一样
that’s about as dense as styrofoam.
系外星体由国际天文学家团队以及
The exoplanet was discovered by an international team of astronomers
普通天文爱好者–像KELT中的部分成员发现
and citizen scientists as part of the KELT,
KELT全称是 千度视场极小望远镜
or Kilodegree Extremely Little Telescope, survey,
它们的发现最近刊登在《天体物理学报》上
and their findings were recently published in The Astrophysical Journal.
虽然他们的两个自动望远镜很小
Even though their two robotic telescopes might be little,
KELT-11b并不是最小的气体星球
KELT-11b isn’t exactly the smallest gas giant on the block.
它距离我们320光年 比木星大百分之四十
The planet, which is about 320 light years away, is almost 40 percent larger
但只有木星五分之一的质量
than Jupiter, but it still only has one-fifth of Jupiter’s mass.
这说明这颗星内部相当膨胀 像泡沫聚苯乙烯
This means the planet is extra puffy and inflated, like styrofoam,
它也是我们观测到的密度第三低的星球
and it’s actually the third-lowest density planet we’ve accurately measured.
这个大气球听起来似乎很可爱 事实上
That big ball of gas could even sound cute, except for the fact
它的表面温度可达到1400摄氏度……因此 就是这样
that it’s more than 1400 degrees Celsius on the surface… so, there’s that.
我们不确定是什么原因导致它有如此低的密度
We’re not sure exactly what caused the planet to have such a low density,
希望我们能解决这个问题！
and we’re hoping to figure that out!
而11b反常的大气层确实帮了我们一个大忙
But what’s especially helpful about 11b is its unusually large atmosphere,
它的大气层向外太空延伸了2.8公里
extending almost 2800 kilometers into space.
大气层会带走很多光 这意味着我们可以对它进行研究
It gets a ton of light from its star, which means it’s a perfect candidate
以便测试我们的大气分析技能
for testing our atmosphere-analyzing skills.
为了确定这个星球周围漂浮的主要物质是什么
To figure out which elements are floating around in a planet’s atmosphere,
天文学家用了一种叫做光谱的方法
astronomers use a process called spectroscopy.
星球会反射和吸收不同数量和波长的光
Planets reflect and absorb different amounts of different wavelengths of light
这种吸收取决于星球的构成元素和大气气体组成
depending on what they’re made of and what’s in their atmosphere,
因此我们可以通过测量光来确定它的组成
and we can measure that light to determine their compositions.
在以后 我们希望能够运用像
In the future, we’re hoping to use technology like the
詹姆斯·韦伯空间望远镜和光谱这种技术去确定
James Webb Space Telescope to identify elements in the atmospheres
类地行星表面的大气成分
around Earth-like planets using spectroscopy.
但现在我们还不可以 我们可以从研究气体星球上获得一些经验
But since we’re not quite there yet, we can get some practice on gas giants
像KELT-11b这样明亮的星星在周围的 这可以帮助我们
like KELT-11b with bright stars nearby, which will help us figure out
了解以后我们还需要怎样改进大气观测技术
what we’ll need to make better atmosphere-observing instruments in the future.
因此亮度波动的星球和密度很低的星球对于我们来说都很有意思
So flickering stars and styrofoam-density planets are fun for us to talk about,
同样它们对研究者来说也很有用
but they’re also really useful for researchers!
这对所有人都是一种双赢
It’s basically a win-win for everyone.
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