In the atmosphere surrounding a hot, puffy gas giant planet orbiting a distant Sun-like star, NASA has captured the distinctive signature of water, along with evidence of clouds and haze.
The presence of specific gas molecules revealed by the observation, based on small dips in the brightness of precise colors of light, is the most detailed of its kind to date, demonstrating Webb’s unprecedented ability to analyze atmospheres at hundreds of of light years away.
Capturing the first clear detection of water in 2013 as the Hubble Space Telescope has analyzed numerous exoplanet atmospheres over the past two decades, Webb’s immediate and more detailed observation marks a major step forward in the quest to characterize potentially habitable planets beyond the Earth’s surface. Land.
WASP-96 b is one of more than 5,000 confirmed exoplanets in the Milky Way. Located approximately 1,150 light-years away in the southern sky constellation of 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 larger, WASP-96 b is much more bloated than any planet orbiting our Sun. It is significantly hotter, with a temperature of over 1000° F. WASP-96 b orbits extremely close to its Sun-like star, only one-ninth the distance between Mercury and the Sun, completing one circuit every 3½ Earth days.
Due to the combination of its large size, short orbital period, puffy atmosphere, and lack of contaminating light from nearby objects in the sky, WASP-96 b is an ideal target for atmospheric observations.
Webb’s Near-Infrared Imaging and Slitless Spectrograph (NIRISS) measured light from the WASP-96 system over 6.4 hours as the planet moved across the star, on June 21. The result is a light curve showing the overall dimming of starlight during transit and a transmission spectrum revealing the change in brightness of individual wavelengths of infrared light between 0.6 and 2.8 microns.
The transmission spectrum reveals previously hidden details of the atmosphere: the unmistakable signature of water, hints of haze, and evidence of clouds that were thought not to exist based on previous observations. While the light curve confirms properties of the planet that had already been determined from other observations (the planet’s existence, size, and orbit),
Researchers can detect and measure the abundance of key gases in a planet’s atmosphere based on the absorption pattern – the locations and heights of the peaks on the graph. In the same way that people have fingerprints and distinctive DNA sequences, atoms and molecules have characteristic patterns of wavelengths that they absorb. A transmission spectrum is created by comparing the starlight filtered through a planet’s atmosphere as it moves through the star with the unfiltered starlight detected when the planet is next to the star.
This part of the spectrum is particularly sensitive to water, as well as other key molecules such as oxygen, methane, and carbon dioxide, which are not immediately apparent in the WASP-96 b spectrum but should be detectable on other exoplanets planned for the future. Webb’s observation. The spectrum of WASP-96 b captured by NIRISS is not only the most detailed near-infrared transmission spectrum of an exoplanet’s atmosphere captured to date, it also covers a remarkably wide range of wavelengths, including red light. visible and part of the spectrum. which has not previously been accessible from other telescopes (wavelengths greater than 1.6 microns).
Researchers will be able to use the spectrum to measure the amount of water vapor in the atmosphere, constrain the abundance of various elements such as carbon and oxygen, and estimate the temperature of the atmosphere with depth. They can then use this information to make inferences about the planet’s overall composition, as well as how, when, and where it formed. The blue line on the graph is a best-fit model that takes into account the data, known properties of WASP-96 b and its star (eg, size, mass, temperature), and assumed characteristics of the atmosphere.
NIRISS is capable of detecting color differences of just a thousandth of a micron (the difference between green and yellow is about 50 microns), and differences in brightness between those colors of a few hundred parts per million. and the clarity of these measurements is made possible by Webb’s cutting-edge design. Its 270-square-foot gold-coated mirror collects infrared light efficiently. Its precision spectrographs scatter light into rainbows of thousands of infrared colors. And its sensitive infrared detectors measure extremely subtle differences in brightness.
In addition, Webb’s extreme stability and its orbital location around Lagrange Point 2, approximately a million miles away from the polluting effects of Earth’s atmosphere, provides an uninterrupted view and clean data that can be analyzed with relative ease. speed.
Over the next year, researchers will use spectroscopy to analyze the surfaces and atmospheres of several dozen exoplanets, from small rocky planets to giants rich in gas and ice. Nearly a quarter of Webb’s Cycle 1 observing time is spent studying exoplanets and the materials that make them up. The extraordinarily detailed spectrum, made by simultaneously analyzing 280 individual spectra captured during the observation, provides just a hint of what Webb has in store for exoplanet research.
This NIRISS observation demonstrates that Webb has the power to characterize the atmospheres of exoplanets, including those of potentially habitable planets, in exquisite detail. Posted by Iraic.info, a news and information agency.