超大型黑洞掙紥吞下銀河系

超大型黑洞掙紥吞下銀河系
Supermassive black hole struggles to swallow Milky Way
Jan 8, 2010

Heart of darkness Sagittarius A* feeds on massive young stars
黑暗的心臟人馬座A *飼食需要大量幼星


Scientists were already aware that the huge black hole at the centre of our galaxy does not consume large amounts of matter, but it could be an even pickier eater than previously thought. That is according to new research done in the US that suggests that the black hole – called Sagittarius A* – has a tendency to blow away 99.99% of the matter available for its consumption.
科學家們已經覺察到，巨大的黑洞在我們的銀河系中心不會消耗大量物質，但它可以比以前想像是更挑剔的食家。這是根據美國的新研究工作，它提出那黑洞-稱為人馬座A * -有傾向去吹散99.99％的現存物質以供其消耗。
Supermassive black holes are awesome phenomena that are believed to exist at the centre of most, if not all, galaxies. They are hundreds of thousands to billions of solar masses and expand by feeding on dust that is blown off massive young stars just outside the black hole's event horizon – the zone beyond which not even light can escape.
特大質量的黑洞是好正的現象，被認為存在於大部分(如果不是全部)銀河系的中心，他們是幾十萬至幾十億個太陽質量和攝食塵埃以擴大，那是黑洞的項目範圍-那區域超過它就連光線也無法逃脫-外面的吹散大型年青恆星。
In the Milky Way, these neighbouring stars are located a relatively large distance away from the black hole mass. For this reason, scientists had calculated that Sagittarius A* should consume only about 1% of the available dust. But now a team of astronomers, including Roman Shcherbakov of Harvard University, claims that it is consuming much less than that.

在銀河系，這些鄰近的恆星位於一段與黑洞質量相對大的距離，為此科學家們計算，人馬座A *應只消耗大約1％的可用灰塵。但現在一隊天文學家小組，包括哈佛大學的羅馬奇謝爾巴科夫，聲稱它是消耗比這少得多。

Gaseous lobes氣體裂片
The team studied an image constructed from a series of observations captured by NASA's Chandra X-ray Observatory, over almost two weeks. This long exposure time, enabled the researchers to get a clear view of the gas surrounding the event horizon, which revealed a series of gaseous lobes stretched in various directions.
To explain this observation, Shcherbakov and his colleagues employ a model that considers the flow of energy between two regions around the black hole: an inner region that is close to the event horizon, and an outer region that includes the black hole's fuel source – the young stars – extending up to a million times farther out than the event horizon. They conclude that collisions between particles in the hot inner region transfer energy to particles in the cooler outer region via conduction, which adds an additional outward pressure so that all but 0.01% of the incoming star dust is blown away.

These findings were presented at the 215th annual meeting of the American Astronomical Society (AAS), which is taking place this week in Washington, DC.

http://physicsworld.com/cws/article/news/41370