JWST: Novel Method to Find Atmospheres on Rocky Worlds

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JWST: Novel Method to Find Atmospheres on Rocky Worlds

Post by bystander » Mon Dec 02, 2019 8:08 pm

Astronomers Propose a Novel Method to Find Atmospheres on Rocky Worlds
NASA | STScI | James Webb Space Telescope | 2019 Dec 02

Webb Telescope Could Detect Heat Signature in a Matter of Hours

Illustration of a Cloudy Exoplanet ~ L. Hustak and J. Olmsted (STScI)
When NASA’s James Webb Space Telescope launches in 2021, one of its most anticipated contributions to astronomy will be the study of exoplanets — planets orbiting distant stars. Among the most pressing questions in exoplanet science is: Can a small, rocky exoplanet orbiting close to a red dwarf star hold onto an atmosphere?

In a series of four papers in the Astrophysical Journal, a team of astronomers proposes a new method of using Webb to determine whether a rocky exoplanet has an atmosphere. The technique, which involves measuring the planet’s temperature as it passes behind its star and then comes back into view, is significantly faster than more traditional methods of atmospheric detection like transmission spectroscopy.

Astronomers are particularly interested in exoplanets orbiting red dwarf stars for a number of reasons. These stars, which are smaller and cooler than the Sun, are the most common type of star in our galaxy. Also, because a red dwarf is small, a planet passing in front of it will appear to block a larger fraction of the star's light than if the star were larger, like our Sun. This makes the planet orbiting a red dwarf easier to detect through this "transit" technique.

Red dwarfs also produce a lot less heat than our Sun, so to enjoy habitable temperatures, a planet would need to orbit quite close to a red dwarf star. In fact, to be in the habitable zone — the area around the star where liquid water could exist on a planet's surface — the planet has to orbit much closer to the star than Mercury is to the Sun. As a result, it will transit the star more frequently, making repeated observations easier. ...

Identifying Candidate Atmospheres on Rocky M dwarf Planets via Eclipse Photometry ~ Daniel D.B. Koll et al Identifying Atmospheres on Rocky Exoplanets Through Inferred High Albedo ~ Megan Mansfield et al Analyzing Atmospheric Temperature Profiles and Spectra of M dwarf Rocky Planets ~ Matej Malik et al A Scaling Theory for Atmospheric Heat Redistribution on Rocky Exoplanets ~ Daniel D.B. Koll
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