Spectrum of an Exoplanet

"WASP-96 b is one of more than 5,000 confirmed exoplanets in the Milky Way. Located roughly 1,150 light-years away in the southern-sky constellation Phoenix, it represents a type of gas giant that has no direct analog in our solar system. With a mass less than half that of Jupiter and a diameter 1.2 times greater, WASP-96 b is much puffier than any planet orbiting our Sun. And with a temperature greater than 1000°F, it is significantly hotter. WASP-96 b orbits extremely close to its Sun-like star, just one-ninth of the distance between Mercury and the Sun, completing one circuit every 3.5 Earth-days."

WASP-96 b 是银河系中已确认的超过5,000颗系外行星之一。它位于南天星座凤凰座，距离约1,150光年。它代表了一种在太阳系中没有直接类比的气态巨行星。其质量不到木星的一半，直径却大1.2倍，比绕行太阳的任何行星都更膨胀。而且，其温度超过1000华氏度，明显更高。WASP-96 b 轨道在其太阳般的恒星周围非常接近，距离其恒星仅是水星到太阳距离的九分之一，绕行周期为3.5地球日。

"The combination of large size, short orbital period, puffy atmosphere, and lack of contaminating light from objects nearby in the sky makes WASP-96 b an ideal target for atmospheric observations."

大尺寸、短轨道周期、蓬松的大气层以及来自天空中附近天体的污染光较少，使WASP-96 b成为进行大气观测的理想目标。

"On June 21, Webb's Near-Infrared Imager and Slitless Spectrograph (NIRISS) measured light from the WASP-96 system for 6.4 hours as the planet moved across the star. The result is a light curve showing the overall dimming of starlight during the transit, and a transmission spectrum revealing the brightness change of individual wavelengths of infrared light between 0.6 and 2.8 microns." (from NASA)

6月21日，韦伯太空望远镜的近红外成像仪和 slitless 谱线仪（NIRISS）对 WASP-96 系统进行了6.4小时的观测，记录了行星掠过恒星时的光变。结果是一条光变曲线，显示了恒星光在凌星过程中的整体变暗，以及一个传输光谱，揭示了从0.6到2.8微米波长的红外光中各个波长的亮度变化。

This is a simulation of the type of spectrum which might be collected from and Earth-like planet with the atmospheric constituents that would be associated with the existence of life on the planet. The data would be collected when the starlight passes through the atmosphere of an Earth-like exoplanet. As the exoplanet moves in front of the star, some of the starlight is absorbed by the gas in that exoplanet's atmosphere and some is transmitted through it. Each element or molecule in the atmosphere's gas absorbs light at a very specific pattern of wavelengths. This creates a spectrum with dips that show where the wavelengths of light are absorbed, as seen in the graph. Each dip is like a "signature" of that element or molecule. The transmission spectrum of an Earth-like planet's atmosphere shows wavelengths of starlight that molecules like the oxygen that we breathe, ozone, water, carbon dioxide, and methane absorb.

这是一个模拟，展示可能从一个类似地球的行星上收集到的光谱类型，该行星的大气成分与该行星上存在生命有关。当恒星光穿过类似地球的系外行星的大气时，数据将被收集。随着系外行星移过恒星，部分星光会被该行星大气中的气体吸收，部分则通过大气。大气中的每个元素或分子都会在非常特定的波长模式下吸收光。这会形成一个有凹陷的光谱，这些凹陷显示了被吸收的光波长，如图所示。每个凹陷都像该元素或分子的‘指纹’。类似地球行星大气的传输光谱显示了被分子如我们呼吸的氧气、臭氧、水、二氧化碳和甲烷吸收的星光波长。

NASA's James Webb Space Telescope will be able to detect some of the most prominent absorption features of certain gas molecules. Even these features will be extremely faint. The more light Webb gathers while looking at the passing planet's atmosphere, the more confidently scientists can identify these features.

NASA的詹姆斯·韦伯太空望远镜将能够检测某些气体分子最显著的吸收特征。即使这些特征也会非常微弱。韦伯望远镜在观察行星大气时收集的光越多，科学家就越能确认这些特征。

韦伯望远镜的系外行星光谱。

詹姆斯·韦伯轨道

Webb太空望远镜能够捕捉到大系外行星WASP-96 b大气层的吸收光谱，当它穿越中心恒星时。图表显示了水蒸气的存在，这证明了该行星有云层，而此前人们认为那里不存在云层，NASA解释道。由于水被认为是任何生命形式存在的必要条件，这一发现引起了极大的关注。它也展示了Webb前所未有的能力，能够分析数百光年之外的行星大气层。