A Hot Jupiter With a Comet-Like Tail

The hot jupiter exoplanet WASP-69b orbits its star so closely that its atmosphere is being blown into space. Researchers made detailed observations of the planet, located about 160 light-years from Earth. They found that it has a comet-like tail extending about 560,000 km into space, about seven times the planet's diameter. Image Credit: Adam Makarenko/W. M. Keck Observatory

About 164 light-years away, a Hot Jupiter orbits its star so closely that it takes fewer than four days to complete an orbit. The planet is named WASP-69b, and it’s losing mass into space, stripped away by the star’s powerful energy. The planet’s lost atmosphere forms a trail that extends about 560,000 km (350,000 miles) into space.

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GJ 367b is Another Dead World Orbiting a Red Dwarf

This artist's concept illustrates a young, red dwarf star surrounded by three planets. There's growing evidence that red dwarfs place serious limits on exoplanet habitability. Image Credit: By NASA/JPL-Caltech - NASA Image of the Day, Public Domain, https://commons.wikimedia.org/w/index.php?curid=17104843

Red dwarf exoplanet habitability is a hot topic in space science. These small dim stars host lots of exoplanets, including small rocky ones the size of Earth. But the little stars emit extremely powerful flares that can damage and strip away atmospheres.

If we’re ever going to understand red dwarf habitability, we need to understand the atmospheres of the exoplanets that orbit them.

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The Discovery of a Hot Neptune that Shouldn’t Exist

exoplanet hot jupiter transiting its star
This artist’s impression shows an ultra-hot exoplanet as it is about to transit in front of its host star. Credit: ESO

1800 light-years away, an unlikely survivor orbits an aged star. This rare planet is called a hot Neptune, and it’s one of only a small handful of hot Neptunes astronomers have found. Hot Neptunes are so close to their stars that the overpowering stellar radiation should’ve stripped away their atmospheres, leaving only a planetary core behind.

But this planet held onto its atmosphere somehow.

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Newborn Exoplanets can be Completely Stripped of Their Atmosphere by Stars

Artist's conception of exoplanet systems that could be observed by PLAnetary Transits and Oscillations of stars (PLATO), a European Space Agency telescope. Credit: ESA - C. Carreau

Newborn exoplanets can have a tough life. They may form an atmosphere, but that atmosphere can be doomed. Their stars can emit intense X-ray and UV radiation, stripping away those atmospheres and laying their surfaces bare.

A team of researchers from the Leibniz Institute for Astrophysics looked at a family of four newborn sibling planets, and tried to understand how their star strips away their gaseous envelopes.

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