【揽瓜阁6.0】Day6 2021.03.13【自然科学-天文、人类】

妥妥

  揽瓜阁俱乐部第六期

  Day6 2021.03.13

【自然科学-天文】

Might there soon be a supernova near Earth?

(The Economist 627字 短精读 )

Betelgeuse is a red supergiant star in Orion, a prominent constellation that spans the celestial equator. It is one of the brightest objects in the night sky, easily visible to the naked eye. It has around ten times the mass of the sun, and if it were at the centre of the solar system its outer edge would stretch beyond the orbit of Mars.

Betelgeuse shines more brightly than the sun partly because it is bigger and thus has more fuel, but also because it is burning through that fuel faster. As a result, it will die much sooner. The sun is around halfway through its 10bn-year lifespan. Betelgeuse’s span will be about 10m years, and it is close to the end of that period—perhaps very close. For, in the past few weeks, astronomers have watched it getting precipitously dimmer and that has made them wonder: could this be a signal that Betelgeuse’s time has come?

When a star such as Betelgeuse runs out of fuel the nuclear reactions in its core which keep it shining stop—and with them the heat and outward radiation pressure needed to balance the force of gravity trying to pull everything inward. At that point, gravity wins. The core collapses. And the resulting shock wave destroys the star in an explosion called a supernova that is temporarily brighter than the rest of Earth’s home galaxy, the Milky Way, put together.

From Earth, a mere 600 light-years away, a Betelgeuse supernova would be spectacular. It would be visible in the daytime for weeks, as bright as the full Moon at night, and able to cast shadows. The last supernova thought to have had such brightness occurred a millennium ago. For astronomers, it would be an unprecedented opportunity to use their armoury of observatories—electromagnetic, gravitational and neutrino—to study the final moments of a star, close-up, as it collapses.

So far, the closest supernova seen since the telescope was invented is sn1987a, spotted more than three decades ago in the Large Magellanic Cloud, a galaxy 160,000 light-years from the Milky Way. But astronomers detected sn1987a only after it had already happened. They have never been able to bring modern instruments to bear on a supernova in the Milky Way itself, and never watched a star in the moments before and during its final explosion.

Betelgeuse is destined to become a supernova soon, that much is certain. But “soon” in astronomical terms could mean anything from today to 100,000 years’ time. If the recent dip in the star’s brightness is not a signal of imminent catastrophe, it could have a number of other explanations. Because the material inside it is always churning as it is heated, Betelgeuse has hotspots on its surface. Sometimes these hotspots are ejected into space, leaving relatively cooler and dimmer areas behind on the star’s surface, and reducing the magnitude of its output of light.

On top of these random events, Betelgeuse is also known to be a semi-regular variable star. This means its brightness changes as it pulses up and down in size. As that happens, its surface area increases or decreases proportionally. Since the brightness per square kilometre of a star tends to remain the same during these pulses, a larger surface area means the star will emit more light overall, and a smaller one, less. Various cycles like this operate within Betelgeuse, with periods ranging from a few hundred Earth days to several thousand.

Astronomers will continue watching the star over the coming weeks. Most, realistically, expect it to brighten up again as the internal cycles continue. But even if there is no supernova this time around, that merely postpones the day when Betelgeuse will undergo a real-world equivalent of the Great Collapsing Hrung Disaster.

Source: The Economist

【自然科学-人类】

Volume of the human brain

（ WSY -224 字 短精读）

Source: WSY

【笔记格式要求】

同学们精读这 2 篇文章并进行笔记打卡

精读笔记格式要求：

1.总结文章中心大意

2.总结分论点或每段段落大意

3.摘抄印象深刻或者觉得优美的句子

4.总结文章中的生词

5.记录阅读时间、总结时间、总时间

这里也给大家三点学习小建议哦~

精读：如遇到读不懂的复杂句，建议找出句子主干，分析句子成分，也可以尝试翻译句子来帮助理解~

SerendipityMona

打卡

球球GMAT780

?

mibem的Amber

t

LostSanta

Language Club 6.0 Day6

红色高亮：生词；难词；易混淆的词
黄色高亮：好的固定搭配；认识但不熟的词
紫色高亮：仍有问题的地方；值得摘录的句子
波浪线：需要注意的结构
淡灰色字体：段落小结

咖喱团

打卡~~Day 6~

Izzieezi

六 Day6

再战请勿拦

第一遍通读：10；Total 40min

【mainpoints】Astronomersnotice that B may be supernova soon 等待两个太阳的出现

【sub-points】

l  Introductionof B and the evidence to support the suspicion that B may turn to supernova soon

l  Introductionof supernova

l  Otherexplanation on the evidence

l  Discussionwith expectation on when B is turning supernova

l  Astronomerswill keep exploring what the evidence exactly means but all in all B is on itsway to supernova

【punchline】

l  Sometimesthese hotspots are ejected into space, leaving relatively cooler and dimmerareas behind on the star’s surface, and reducing the magnitude of its output of light. (看了好几遍才理解)

l  But even if there is no supernova this timearound, that merely postpones the day when Betelgeuse will undergo a real-worldequivalent of the Great Collapsing Hrung Disaster. (so sad)

【vocabulary】

celestial equator 天体赤道

【小T comment】

第一次知道supernova这个词是腾讯超新星运动会，于是一直以为supernova是意味着充满希望。看到这篇文章才了解到，原来supernova根本是烟花，极耀眼但同时也意味着陨落的意思……为什么腾讯要给自己的节目起一个这么悲情的名字

以及，天上两个‘太阳’持续几周，临时‘太阳’比原太阳更亮，地球的其他方面不会有影响么？（刚刚百度了一下，可能真没啥影响）

是马上考试所以焦虑了么，怎么看完这篇感觉这么down……

【第一遍通读】4min；【total】 20min

【mainpoints】seekingthe reasons why human’s brain has shrank since prehistorical era

1hour?

【sub-points】

l  Afact that human’s brain volume has decreased since prehistorical period

l  Somescientists argue that this decrease is with that of body mass, 然而并不是, brainvolume shrank faster than body mass did

l  Oneexplanation is the agricultural society makes the large volume unnecessary

l  Theother one, which the author supports, is that being domestic, which led to the brainshrinkage, meet human survival request better. ——peace and love

【punchline】

l  Less-aggressiveindividuals may haveprovoked fewer unnecessary conflicts, improving their reproductive successin societies demanding closecooperation.

l  Likemodern humans, domesticate mammals have smaller brain, flatter faces, smallerteeth, and more gracefully slender builds than their wild ancestors. ——感觉解锁了面相学

【vocabulary——seepunchline】

Shrink 缩小，畏缩，退回，缩水

Retention

slender builds 纤细的体格，build n.有体型的意思

【小T comment】

还在supernova的伤感情绪中，就看到了本文首句——人类大脑从史前时代就开始畏缩。。。感觉今天都无法开心了。

        还好最后原来是一篇love & peace的主题，稍稍被安抚了一下。可以去刷题了

Alex_xuan

打卡~wsy yyds!

英俊子遥想明天

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