澳天文学家发现钻石星球-英语点津

澳洲天文学家刚刚发现了一颗他们认为是由钻石组成的行星。这颗隐藏在星河中的璀璨宝石直径可能长达6万公里——是地球直径的5倍。从它的高密度看，它的大部份原材料应该是碳原子，碳原子互相撞击构成了水晶般的结构。在天文学家们绘制的彩图上，这颗“钻石星球”正围绕着画面中央的一颗脉冲星（pulsar）公转。公转轨道由虚线表示。蓝色的线条代表这颗脉冲星释放出的无线电波束。脉冲星被认为是质量巨大的恒星通过超新星爆发方式坍塌后遗留下的核心产物，就像一种小小的，已经丧失了活力的，会自转的恒星。它们的直径一般仅20公里，却能每秒发射175次无线电波束，堪称宇宙中的“灯塔”。钻石星球的这颗脉冲星距离银河系大约4000光年之遥。

Astronomers have spotted an exotic planet that seems to be made of diamond racing around a tiny star in our galactic backyard.

The new planet is far denser than any other known so far and consists largely of carbon. Because it is so dense, scientists calculate the carbon must be crystalline, so a large part of this strange world will effectively be diamond.

"The evolutionary history and amazing density of the planet all suggest it is comprised of carbon -- i.e. a massive diamond orbiting a neutron star every two hours in an orbit so tight it would fit inside our own Sun," said Matthew Bailes of Swinburne University of Technology in Melbourne.

澳天文学家发现钻石星球

Lying 4,000 light years away, or around an eighth of the way toward the center of the Milky Way from the Earth, the planet is probably the remnant of a once-massive star that has lost its outer layers to the so-called pulsar star it orbits.

Pulsars are tiny, dead neutron stars that are only around 20 kilometers (12.4 miles) in diameter and spin hundreds of times a second, emitting beams of radiation.

In the case of pulsar J1719-1438, the beams regularly sweep the Earth and have been monitored by telescopes in Australia, Britain and Hawaii, allowing astronomers to detect modulations due to the gravitational pull of its unseen companion planet.

The measurements suggest the planet, which orbits its star every two hours and 10 minutes, has slightly more mass than Jupiter but is 20 times as dense, Bailes and colleagues reported in the journal Science on Thursday.

In addition to carbon, the new planet is also likely to contain oxygen, which may be more prevalent at the surface and is probably increasingly rare toward the carbon-rich center.

Its high density suggests the lighter elements of hydrogen and helium, which are the main constituents of gas giants like Jupiter, are not present.

Just what this weird diamond world is actually like close up, however, is a mystery.

"In terms of what it would look like, I don't know I could even speculate," said Ben Stappers of the University of Manchester. "I don't imagine that a picture of a very shiny object is what we're looking at here."