垂死的恒星發(fā)出的光可以粉碎小行星

垂死的恒星發(fā)出的光可以粉碎小行星

Even stars that don’t end their lives in supernovae can spell catastrophe for the smallest members of their solar system. New research suggests that the light of dying stars is enough to pulverize asteroids located hundreds of times further than the Earth-Sun distance from their star.

即使是那些沒有在超新星中結束生命的恒星也會給太陽系中最小的成員帶來災難。新的研究表明，瀕死恒星發(fā)出的光足以粉碎距離其恒星數百倍于地球-太陽距離的小行星。

The study, published in the Monthly Notices of the Royal Astronomical Society, looked at the consequence of the YORP effect in stellar systems. Named after the four scientists that contributed to the idea (Yarkovsky, O'Keefe, Radzievskii, and Paddack), the YORP effect is when an asteroid spins itself to death due to stellar radiation.

這項研究發(fā)表在《皇家天文學會月刊》上，研究了約普效應對恒星系統(tǒng)的影響。“約普效應”是以四位科學家的名字命名的，這四位科學家分別是:雅科夫斯基、奧基夫、拉濟耶夫斯基和帕達克。

Alfredo Carpineti

Starlight has a small but not zero momentum. As we have seen with the successful solar sail tests in the last decade or so, photons from the Sun can push objects around. When starlight hits an asteroid, it is absorbed, redistributed internally, and then reemitted at a different location.

星光有一個小但不是零的動量。正如我們在過去十年左右成功的太陽帆試驗中所看到的，來自太陽的光子可以推動物體。當星光撞擊小行星時，它被吸收，在內部重新分布，然后在不同的位置重新發(fā)射。

Asteroids are large piles of space rocks that often remain together due to weak gravity; however, they are not well mixed, so the heating from stellar radiation and the subsequent emissions are not balanced. This imbalance in the emissions produces a small torque. Over time and with the star getting brighter and brighter, the torque increases. Since the gravity exerted on the asteroids is too weak to counterbalance the forces pulling the asteroids apart, the space rocks become dust.

小行星是一大堆太空巖石，由于重力較弱，它們通常會保持在一起;然而，它們并沒有很好地混合在一起，因此恒星輻射產生的熱量和隨后的輻射并不平衡。這種排放的不平衡產生了一個小扭矩。隨著時間的推移，恒星變得越來越亮，扭矩也隨之增大。由于施加在小行星上的引力太弱，無法抵消把小行星拉開的力，太空巖石就變成了塵埃。

“When a typical star reaches the giant branch stage, its luminosity reaches a maximum of between 1,000 and 10,000 times the luminosity of our Sun. Then the star contracts down into an Earth-sized white dwarf very quickly, where its luminosity drops to levels below our Sun’s. Hence, the YORP effect is very important during the giant branch phase, but almost non-existent after the star has become a white dwarf,” lead author Dr Dimitri Veras, from the University of Warwick’s Astronomy and Astrophysics Group, said in a statement.

“當一顆典型的恒星達到大分支階段時，它的光度最大達到太陽光度的1000到10000倍。然后這顆恒星迅速收縮成地球大小的白矮星，其光度下降到低于太陽的亮度。因此，約普效應在大分支階段非常重要，但在恒星變成白矮星后幾乎不存在。華威大學天文和天體物理小組的首席作者迪米特里·維拉斯博士在一份聲明中說。

The work provides insight into the future of our Solar System. In about 6 billion years, our Sun will have run out of fuel, shedding its outer layers and collapsing into a white dwarf. This will mean bye to the asteroid belt in record time.

這項工作為我們了解太陽系的未來提供了視角。在大約60億年后，我們的太陽將耗盡燃料，脫離它的外層，坍縮成一顆白矮星。這意味著小行星帶將在創(chuàng)紀錄的時間內消失。

“For one solar-mass giant branch stars – like what our Sun will become – even exo-asteroid belt analogues will be effectively destroyed. The YORP effect in these systems is very violent and acts quickly, on the order of a million years. Not only will our own asteroid belt be destroyed, but it will be done quickly and violently. And due solely to the light from our Sun," said Dr Veras.

“對于一個太陽質量的巨型分支恒星——就像我們的太陽將會變成的樣子——即使是外小行星帶的類似物也會被有效地摧毀。約珥普效應在這些系統(tǒng)中非常強烈，而且作用迅速，大約有一百萬年的時間。我們自己的小行星帶不僅會被摧毀，而且會被迅速而猛烈地摧毀。而這僅僅是由于來自太陽的光。”維拉斯博士說。

The simulations suggest that the size of the debris will plateau when objects are less than 100 meters (330 feet) across, as these often have quite high internal strength. The researchers think that by studying emissions from the asteroid debris around white dwarfs, it might be possible to gain insight into what the stellar system used to be like before the star died.

模擬表明，當物體直徑小于100米(330英尺)時，碎片的大小將趨于平穩(wěn)，因為這些物體通常具有相當高的內部強度。研究人員認為，通過研究白矮星周圍小行星碎片的排放，有可能了解恒星死亡前的恒星系統(tǒng)。