离地球只有1000光年的黑洞

天文学家发现了一个黑洞，它潜伏在离地球只有1000光年的地方

We can't see them, but they're out there - stellar-mass black holes, peppering the galaxy. And they're closing in. Astronomers have just identified the closest black hole to Earth they've spotted yet, at less than a third of the distance of the previous record-holder.

我们看不到它们，但它们在那里-恒星状的黑洞，给银河系增添了色彩。他们正在慢慢靠近我们。天文学家刚刚发现了离地球最近的黑洞，距离上一个记录保持者不到三分之一。

This nearby black hole has evaded detection so far since it's very small, and very quiet - detecting black holes is that much harder when they aren't actively slurping down matter from their surrounding space, since they neither emit nor reflect any detectable radiation whatsoever.

到目前为止，附近的黑洞非常小，而且非常安静，因此无法检测-当黑洞没有主动从周围空间吸取物质时，检测黑洞就困难得多，因为它们既不会发射也不会反射任何可检测到的辐射。

But the newly discovered object had a tell. It's in a triple star system, with two B-type main sequence stars, visible from Earth with the naked eye, and previously thought to be a binary system, called HR 6819.

但是这个新发现的黑洞却有了回音。它是由三颗恒星组成的系统，其中有两个B型主序列恒星，用肉眼可以从地球上看到，并且以前被认为是双星系统，称为HR 6819。

When astronomers took observations of the system as part of a survey on binary stars, they found something awry. The orbits of those two main sequence stars seemed to be tugged askew.

当天文学家对双星观测进行系统观测时，他们发现有些不对劲。这两个主要序列恒星的轨道似乎被拉歪了。

Follow-up observations tracking the star using the MPG/ESO 2.2-metre telescope at European Southern Observatory's (ESO) La Silla Observatory in Chile clinched it. One of the stars, with an estimated mass between 5 and 7 times the mass of the Sun, orbits a gravitational centre of the system every 40 days - not the other star, which is much farther out.

在欧洲南方天文台(ESO)位于智利的拉希拉天文台(La Silla Observatory)使用MPG/ESO 2.2米望远镜跟踪这颗恒星时锁定了它。其中一颗恒星的质量估计在太阳质量的5到7倍之间，每40天绕着系统的一个引力中心运行一周，而另一颗恒星的质量则远得多。

When analysed, these orbits suggested there were not two, but three objects dancing around each other in orbit. Since the third object was invisible, there was one thing it was far more likely to be than anything else.

分析后，表明在轨道上不是两个而是三个物体在彼此周围跳舞。由于第三个物体是不可见的，因此有一件事比其他任何事物都更有可能。

"An invisible object with a mass at least four times that of the Sun can only be a black hole," said astronomer Thomas Rivinius of the European Southern Observatory. Therefore, "this system contains the nearest black hole to Earth that we know of."

欧洲南方天文台的天文学家托马斯里维纽斯说：“一个质量至少是太阳质量四倍的隐形物体，只能是黑洞。”。因此，“这个系统包含了我们所知离地球最近的黑洞。”

And it's just over 1,000 light-years away. Previously, the closest known black hole, A 0620-00, was measured at a distance of 3,300 light-years away.

离我们只有1000光年。此前，已知离我们最近的黑洞A 0620-00，距离我们3300光年。