跳转到内容

File:Artist's impression of a white dwarf devouring a minor planet.jpg

页面内容不支持其他语言。
這個文件來自維基共享資源
维基百科,自由的百科全书

原始文件 (5,000 × 3,799像素,文件大小:2.95 MB,MIME类型:image/jpeg


摘要

描述
English: Scientists using NASA’s repurposed Kepler space telescope, known as the K2 mission, have uncovered strong evidence of a tiny, rocky object being torn apart as it spirals around a white dwarf star. This discovery validates a long-held theory that white dwarfs are capable of cannibalizing possible remnant planets that have survived within its solar system.

“We are for the first time witnessing a miniature “planet” ripped apart by intense gravity, being vaporized by starlight and raining rocky material onto its star,” said Andrew Vanderburg, graduate student from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and lead author of the paper published in Nature.

As stars like our sun age, they puff up into red giants and then gradually lose about half their mass, shrinking down to 1/100th of their original size to roughly the size of Earth. This dead, dense star remnant is called a white dwarf.

The devastated planetesimal, or cosmic object formed from dust, rock, and other materials, is estimated to be the size of a large asteroid, and is the first planetary object to be confirmed transiting a white dwarf. It orbits its white dwarf, WD 1145+017, once every 4.5 hours. This orbital period places it extremely close to the white dwarf and its searing heat and shearing gravitational force.

During its first observing campaign from May 30, 2014 to Aug. 21, 2014, K2 trained its gaze on a patch of sky in the constellation Virgo, measuring the minuscule change in brightness of the distant white dwarf. When an object transits or passes in front of a star from the vantage point of the space telescope, a dip in starlight is recorded. The periodic dimming of starlight indicates the presence of an object in orbit about the star.

A research team led by Vanderburg found an unusual, but vaguely familiar pattern in the data. While there was a prominent dip in brightness occurring every 4.5 hours, blocking up to 40 percent of the white dwarf's light, the transit signal of the tiny planet did not exhibit the typical symmetric U-shaped pattern. It showed an asymmetric elongated slope pattern that would indicate the presence of a comet-like tail. Together these features indicated a ring of dusty debris circling the white dwarf, and what could be the signature of a small planet being vaporized.

“The eureka moment of discovery came on the last night of observation with a sudden realization of what was going around the white dwarf. The shape and changing depth of the transit were undeniable signatures,” said Vanderburg.

In addition to the strangely shaped transits, Vanderburg and his team found signs of heavier elements polluting the atmosphere of WD 1145+017, as predicted by theory.

Due to intense gravity, white dwarfs are expected to have chemically pure surfaces, covered only with light elements of helium and hydrogen. For years, researchers have found evidence that some white dwarf atmospheres are polluted with traces of heavier elements such as calcium, silicon, magnesium and iron. Scientists have long suspected that the source of this pollution was an asteroid or a small planet being torn apart by the white dwarf's intense gravity.
日期
来源 https://www.nasa.gov/ames/kepler/nasa-k2-finds-dead-star-vaporizing-mini-planet
作者 CfA/Mark A. Garlick

许可协议

This media has been created by Harvard-Smithsonian Center for Astrophysics.
This website states: "The Center for Astrophysics/Harvard & Smithsonian follows the Smithsonian Institution's Open Access (CC0) policy. Our digital assets are in the public domain and are thus free of copyright restrictions and may be used for any purpose, free of charge, without further permission."
Creative Commons CC-Zero 本作品采用知识共享CC0 1.0 通用公有领域贡献许可协议授权。
采用本宣告发表本作品的人,已在法律允许的范围内,通过在全世界放弃其对本作品拥有的著作权法规定的所有权利(包括所有相关权利),将本作品贡献至公有领域。您可以复制、修改、传播和表演本作品,将其用于商业目的,无需要求授权。

说明

添加一行文字以描述该文件所表现的内容

此文件中描述的项目

描繪內容

image/jpeg

2c55007810f2b4f7c29b5ad4a73a58e7aa2a6ec5

3,095,775 字节

3,799 像素

5,000 像素

文件历史

点击某个日期/时间查看对应时刻的文件。

日期/时间缩⁠略⁠图大小用户备注
当前2016年8月14日 (日) 18:152016年8月14日 (日) 18:15版本的缩略图5,000 × 3,799(2.95 MB)MarioProtIVUser created page with UploadWizard

以下页面使用本文件:

全域文件用途

以下其他wiki使用此文件:

元数据