VOA慢速英语2020 研究表明太阳的活跃度不如类似恒星（在线收听）

Study Suggests Sun Less Active than Similar Stars

A new study suggests the sun appears to experience far fewer changes in brightness and intensity than other stars like it.

Researchers reported last week on their examination of 369 stars. They compared each one to the sun in terms of surface temperature, size and rotation. They found that on average, the other stars had five times more brightness variability than our sun.

A report on the study and its findings was published in Science magazine.

The lead author was Timo Reinhold, an astronomer with the Max Planck Institute for Solar System Research in Germany. He told the Reuters news agency that the variability in brightness re???sults from dark spots on the surface of the star moving in and out of view.

"A direct measure of solar activity is the number of sunspots on the surface," Reinhold said. "Finding such stars with very similar parameters as our sun but being five times more variable was surprising."

The sun — made up mainly of hydrogen and helium — is an average-sized star that formed more than 4.5 billion years ago. It stretches about 1.4 million kilometers across and has a surface temperature of 5,500 degrees Celsius.

The researchers compared scientific data on the similar stars to historical records of the sun's activity. The records included about 400 years of observational data on sunspots. The researchers also studied about 9,000 years of data based on chemical element variants in tree rings and ice buildup tied to solar activity. These records show the sun has not been much more active than it is now.

The researchers said increased magnetic activity related to sunspots can lead to electromagnetic events that affect Earth. For example, large releases of plasma — a collection of charged particles — from outer areas of the sun's atmosphere could cause problems for satellites and other communications equipment. Other electromagnetic activities could also result in such difficulties.

The discovery that the sun does not experience as many changes as other stars may be good news for life on Earth.

A much more active sun might have had more major effects on Earth's geology and ancient climate. "A 'too active' star would definitively change the conditions for life on the planet, so living with a quite boring star is not the worst option," Reinhold said.

The findings, he noted, do not rule out the possibility that the sun may be in a quiet period and could become more variable in the future.

However, the researchers say there are no signs that solar activity will be increasing any time soon.

"For the last decade, the sun has been showing itself to be rather weakly active, even by its own low standards," they said in a statement. "Predictions of activity for the next 11 years indicate that this will not change soon."

I'm Bryan Lynn.

研究表明太阳的活跃度不如类似恒星

一项新研究表明，太阳在亮度和强度上的变化似乎比其他类似恒星要少得多。

上周，研究人员报告了他们对369颗恒星的调查结果。他们从表面温度、大小和自转角度等方面将每颗恒星与太阳进行对比。他们发现，平均来说，其他恒星的亮度变化是太阳的5倍。

有关这项研究及其结果的报告发表在《科学》期刊上。

这篇报告的首席作者是德国马克斯·普朗克太阳系研究所的天文学家蒂莫·莱因霍尔德。他对路透社表示，亮度波动由恒星表面的黑点在视野内外移动所引起。

莱因霍尔德表示：“太阳活跃度的直接衡量指标是其表面太阳黑子的数量。参数与太阳类似的恒星，波动却是太阳的5倍，这一发现令人惊讶。”

太阳主要由氢和氦组成，是形成于45亿年前的一颗平均大小的恒星。太阳的直径约为140万平方千米，表面温度为5500摄氏度。

研究人员将类似恒星的科学数据与太阳活跃度的历史记录进行了比较。这些记录包括大约400年的太阳黑子观测数据。研究人员还研究了一份约9000年的数据，该数据基于与太阳活跃度有关的树木年轮和冰堆积的化学元素变异。这些记录显示，太阳的活跃度并不比现在高太多。

研究人员表示，与太阳黑子有关的磁场活动增加可能导致影响地球的地磁事件。举例来说，太阳大气层外层大量释放的等离子体（带电粒子的集合）可能会给卫星和其他通信设备带来问题。其他电磁活动也可能导致这类问题。

太阳所经历的变化不如其他恒星多这一发现，对地球上的生命来说可能是个好消息。

更加活跃的太阳可能对地球的地质和古代气候产生更大影响。莱因霍尔德表示，“过于活跃的恒星肯定会改变地球上存在生命的条件，因此，与一颗相当无聊的恒星一起生活并不是最坏的选择。”

他指出，这些发现不排除太阳也许处于平静期的可能性，太阳可能在未来变得更加活跃。

然而，研究人员表示，没有迹象表明太阳的活跃度将在短期内增加。

他们在声明中表示，“在过去的十年里，太阳一直表现出相当弱的活跃度，即使以太阳的低标准来衡量也是如此。对未来11年活动的预测表明，这种情况不会很快改变。”

布莱恩·林恩报道。