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Astronomers Detect Smallish Exoplanet's Infrared Glow

A space-based telescope picked up faint thermal radiation from a "super-Earth" planet 40 light-years away. John Matson reports

Here’s a hot topic: astronomers have detected infrared radiation from a faraway planet not much bigger than our own.

It’s not as if they were able to take a picture, though. After all, the star 55 Cancri and the five planets orbiting it are just a single point of light in the night sky, some 40 light-years away. But researchers determined how much of the infrared light in that little point comes from one of the planets, known as 55 Cancri e.

The Spitzer Space Telescope caught the planet orbiting behind the star and out of view. Each time that happened the total thermal radiation coming from the entire system dipped slightly—by about a hundredth of a percent. That’s the portion attributed to the planet. It may not sound like much, but the planet’s glow implies that it’s roasting. No surprise, since it orbits extremely close to its star.

Such measurements have never been made for such a small exoplanet. 55 Cancri e is what’s called a super-Earth. It’s only about two times the diameter of our own planet. And at about 2,000 degrees Celsius, it’s super-sweltering. But being able to figure all that out is pretty cool.

[The above text is a transcript of this podcast.]

[Detection of Thermal Emission from a Super-Earth,” by Brice-Olivier Demory et al. at arXiv.org]

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