參宿四已經(jīng)停止變暗，并再次變亮

參宿四已經(jīng)停止變暗，并再次變亮

After months of progressive dimming, Betelgeuse has started brightening again. The pronounced dimming event that this peculiar red giant star experienced was the most severe in recorded history, but it appears to have come to an end.

經(jīng)過幾個(gè)月的逐漸變暗，參宿四再次開始變亮。這顆奇特的紅巨星所經(jīng)歷的明顯的變暗事件是有記錄以來最嚴(yán)重的，但它似乎已經(jīng)結(jié)束了。

Observations during February showed that the rate of dimming was slowing down following the dramatic drop in brightness late last year. Now astronomers have seen signs of rebrightening, discussing the increase in luminosity in an Astronomer’s Telegram as well as partially solving the mystery of the dimming event.

2月份的觀測(cè)表明，隨著去年年底亮度的急劇下降，調(diào)暗的速度正在放緩?，F(xiàn)在天文學(xué)家們已經(jīng)看到了重新變亮的跡象，他們?cè)谝晃惶煳膶W(xué)家的電報(bào)中討論了亮度的增加，并部分地解決了變暗事件的謎團(tuán)。

Alfredo Carpineti

It is well known that Betelgeuse is a semiregular variable star. This means that there is some periodicity to its brightness changes, but how much it varies and the precise length of these periods are not set in stone. The lowest point of the dip that has just concluded took place about 424 days after the last measured minimum, matching up with the star's primary period, which takes place every 420-430 days.

眾所周知，參宿四是一顆半規(guī)則的變星。這意味著它的亮度變化有一定的周期性，但它變化的程度和這些周期的精確長(zhǎng)度并不是固定不變的。剛剛得出結(jié)論的傾角最低點(diǎn)發(fā)生在最后一次測(cè)量最小值后的424天，與恒星的主周期相匹配，主周期每420-430天發(fā)生一次。

What remains to be understood is why the reduction in brightness was so significant this time around. Since last September, Betelgeuse has got more than 2.5 times dimmer, dropping out of the top 20 brightest stars in the night sky. And for this reason, astronomers want more telescopes on this peculiar object.

目前尚不清楚的是，為什么這一次亮度的降低如此顯著。自去年9月以來，參宿四的亮度已經(jīng)下降了2.5倍以上，在夜空中最亮的20顆星星中，參宿四被排除在外。由于這個(gè)原因，天文學(xué)家想要更多的望遠(yuǎn)鏡來觀測(cè)這個(gè)奇特的物體。

“Observations of all kinds continue to be needed to understand the nature of this unprecedented dimming episode and what this surprising star will do next,” the researchers wrote in the latest Astronomer’s Telegram.

研究人員在最新一期的《天文學(xué)家電報(bào)》中寫道:“我們?nèi)孕枰ㄟ^各種各樣的觀察來了解這次前所未有的暗化事件的本質(zhì)，以及這顆令人驚訝的恒星接下來會(huì)發(fā)生什么。”

Some of these observations are already coming in with another Astronomer’s Telegram, which details brand new infrared observations of the star. The infrared photometry measured in February does not differ from previous measurements, even those from decades ago, and these values are a good proxy for the total luminosity of the star. Since they have not varied much, the researchers behind these observations suggest that the changes in brightness are to do exclusively with the outer layers of Betelgeuse.

其中一些觀測(cè)結(jié)果已經(jīng)和另一位天文學(xué)家的電報(bào)一起寄來了，電報(bào)中詳細(xì)介紹了對(duì)這顆恒星的全新的紅外觀測(cè)結(jié)果。今年2月進(jìn)行的紅外光度測(cè)定法與以往的測(cè)量方法沒有什么不同，甚至與幾十年前的測(cè)量方法也沒有什么不同，這些數(shù)值可以很好地反映出這顆恒星的總光度。由于它們的亮度變化不大，這些觀測(cè)背后的研究人員認(rèn)為，亮度的變化只與參宿四的外層有關(guān)。

Betelgeuse is a red supergiant star with an estimated mass almost 12 times that of our Sun, but much much larger in size. If it switched place with the Sun, it would extend past the orbit of Jupiter. The star has a low density and its outer layers are strongly affected by even small changes. It might be surprising to know that the star is not spherical, instead, its shape changes as a result of the many forces acting on it.

參宿四是一顆紅色的超巨星，據(jù)估計(jì)其質(zhì)量幾乎是太陽的12倍，但體積要大得多。如果它與太陽交換位置，它將會(huì)越過木星的軌道。這顆恒星的密度很低，即使是很小的變化也會(huì)強(qiáng)烈地影響它的外層。知道這顆恒星不是球形可能會(huì)讓人驚訝，相反，它的形狀會(huì)因?yàn)樽饔迷谒厦娴脑S多力而改變。