Astronomy Picture of the Day——遥远的系外行星上发现的水气

Water Vapor Discovered on Distant Exoplanet 
Illustration Credit: ESA, NASA, Hubble; Artist: M. Kornmesser

Explanation: Where else might life exist? One of humanity's great outstanding questions, locating planets where extrasolar life might survive took a step forward recently with the discovery of a significant amount of water vapor in the atmosphere of distant exoplanet K2-18b. The planet and it parent star, K2-18, lie about 124 light years away toward the constellation of the Lion (Leo). The exoplanet is significantly larger and more massive than our Earth, but orbits in the habitable zone of its home star. K2-18, although more red than our Sun, shines in K2-18b's sky with a brightness similar to the Sun in Earth's sky. The discovery was made in data from three space telescopes: Hubble, Spitzer, and Kepler, by noting the absorption of water-vapor colors when the planet moved in front of the star. The featured illustration imagines exoplanet K2-18b on the right, its parent red dwarf star K2-18 on the left, and an unconfirmed sister planet between them.

遥远的系外行星上发现的水气

除了地球之外，生命还有可能存在于何处呢？这是人类最重大且未解的难题之一，近日，随着在遥远的系外行星K2-18b大气中发现水气，这位确定太阳系外生命可能生存的行星位置又向前迈进了一步。这颗系外行星和它的母星K2-18位于狮子座方向，距离地球约124光年。它的体积比地球大得多，而且质量也更大，但它的轨道位于其主星的宜居带。尽管K2-18比太阳更红，但它在K2-18b天空中显现的亮度和地球天空中看到的太阳亮度相近。这一发现是综合哈勃、斯皮策和开普勒三架太空望远镜的数据得出的，它们记录了当行星移动到恒星前方时，水气颜色的吸收情况。这幅精彩的照片呈现了位于右侧的系外行星K2-18b，位于左侧的母星红矮星K2-18，以及它们之间一颗未经确认的姊妹行星。

高清原图地址：

https://apod.nasa.gov/apod/image/1909/K218b_ESAKornmesser_6000.jpg

近期文章：

Astronomy Picture of the Day——都灵城上空的月华

Astronomy Picture of the Day——月球后方的土星

Astronomy Picture of the Day——哈勃首次在系外行星上发现水汽

NASA

微店