科学家发现银河系第二大已知黑洞

Astronomers have discovered a black hole with a mass about 33 times greater than that of our sun. It is the second biggest black hole known in the Milky Way. Only the supermassive black hole at the center of the galaxy is bigger.
天文学家发现了一个质量大约是太阳质量33倍的黑洞。它是银河系中已知的第二大黑洞。只有银河系中心的超大质量黑洞比它更大。

The newly identified black hole is about 2,000 light-years from Earth says a new study in the publication Astronomy & Astrophysics. A light year is about 9.5 trillion kilometers.
《天文学与天体物理学》杂志上的一项新研究称，新发现的黑洞距离地球约2000光年。一光年大约是9.5万亿公里。

The black hole is in the constellation Aquila, and has a companion star orbiting it, researchers said on Tuesday.
研究人员周二表示，这个黑洞位于天鹰座，有一颗伴星围绕它运行。

Black holes are extremely dense objects. They have gravity so strong not even light can escape, making it difficult to find them. The European Space Agency's Gaia mission found the black hole. Gaia is carrying out a huge stellar count.
黑洞是密度极高的物体。它们的引力强到甚至光都无法逃脱，使得很难被发现它们。欧洲航天局的盖亚任务发现了这个黑洞。盖亚正在进行一次大型恒星计数。

The scientists saw that the black hole caused its companion star to wobble. Data from the European Southern Observatory's Chile-based Very Large Telescope and other ground-based observatories confirmed the black hole's mass.
科学家们看到黑洞导致其伴星摆动。欧洲南方天文台位于智利的超大望远镜和其他地面天文台的数据证实了这个黑洞的质量。

"This black hole is not only very massive, it is also very peculiar," said Pasquale Panuzzo. He is a research engineer at the French research agency CNRS and lead writer of the study.
帕斯奎尔·帕努佐说：“这个黑洞不仅质量很大，而且非常奇特。”他是法国国家科研中心的研究工程师，也是该研究的主要作者。

For instance, the black hole, called Gaia BH3, and its companion are traveling within the galaxy in the opposite direction of how stars usually orbit in the Milky Way.
例如，这个名为Gaia BH3的黑洞及其伴星在银河系内的运动方向与恒星在银河系中的常规轨道方向相反。

Gaia BH3 probably formed after the supernova, or explosive death, of a star that was more than 40 times as large as the sun, the researchers said.
研究人员表示，盖亚BH3可能是在一颗比太阳大40多倍的恒星爆炸性死亡后形成的。

Black holes that result from the collapse of a single star are called stellar black holes. Gaia BH3 is the largest-known stellar black hole, said astronomer and study co-author Tsevi Mazeh of the Tel Aviv University in Israel.
由单个恒星坍塌产生的黑洞被称为恒星黑洞。以色列特拉维夫大学的天文学家兼研究合著者Tsevi Mazeh说，盖亚BH3是已知最大的恒星黑洞。

Stellar black holes are small compared to supermassive black holes at the center of most galaxies. Sagittarius A* is the supermassive black hole at the heart of the Milky Way. It is 4 million times the mass of the sun and is located about 26,000 light-years from Earth.
与大多数星系中心的超大质量黑洞相比，恒星黑洞很小。射手座A*是银河系中心的超大质量黑洞。它的质量是太阳的400万倍，距离地球约26000光年。

Gaia BH3's progenitor star was made almost entirely of hydrogen and helium. Stars in the early universe were of similar chemical formation, known as low metallicity. The progenitor star had formed early in the universe's history, perhaps two billion years after the Big Bang. When it exploded at the end of its lifespan it released material into space. The remains violently collapsed to form a black hole.
盖亚BH3的前身星几乎完全由氢和氦组成。早期宇宙中的恒星也有这种被称为低金属性的类似化学形成。这颗前身星形成于宇宙历史的早期，可能在宇宙大爆炸后20亿年。当它寿终正寝发生爆炸时，它将物质释放到太空中。其残骸剧烈坍塌形成一个黑洞。

The discovery of Gaia BH3 supports stellar evolution models showing that massive stellar black holes can be produced only by a low metallicity star like this one's progenitor star, Panuzzo said.
帕努佐说，盖亚BH3的发现证实了恒星演化模型，该模型表明，只有这颗前身星这样的低金属丰度恒星才能产生大质量恒星黑洞。

Gaia BH3's companion star is about 76 percent of the mass of the sun. It is a bit colder, but around 10 times brighter.
盖亚BH3的伴星质量约为太阳质量的76%。它比太阳温度稍低，但亮度大约是它的10倍。

A measure called an astronomical unit (AU) is the distance between the earth and the sun. Gaia BH3's companion star orbits the black hole at a changing distance between 4.5 AU and 29 AU. By comparison, Jupiter orbits around 5 AU from the sun and Neptune around 30 AU.
地球和太阳之间的距离是一种被称为天文单位的的度量。盖亚BH3的伴星围绕黑洞运行，距离在4.5天文单位到29天文单位之间。相比之下，木星的轨道距离太阳约为5天文单位，海王星的轨道距离为30天文单位。

Elisabetta Caffau is an Observatoire de Paris astronomer and a co-writer of the study. She said she was surprised that "the chemical composition of this companion star does not show anything special, so it was not affected by the supernova explosion of the black hole."
伊丽莎白·卡福是巴黎天文台的天文学家，也是这项研究的合著者。她说，她很惊讶“这颗伴星的化学成分没有显示出任何特殊之处，所以它没有受到这个黑洞发生超新星爆炸的影响。”

Scientists are not sure just how big stellar black holes can be.
科学家们不确定恒星黑洞究竟能有多大。

"The maximum mass for a stellar black hole is a matter of active scientific debate," Panuzzo said.
帕努佐说：“恒星黑洞的最大质量是一个活跃的科学争论问题。”