artist drawing of HR8799e

Astronomers Look Directly At HR8799e For First Time With Optical Interferometry

The exoplanet HR8799e isn’t a new discovery. It was first discovered in 2010 orbiting a young main-sequence star (a star fusing hydrogen atoms to form helium in their cores, like our Sun) about 129 light-years from Earth.

The Gist: Astronomers used optical interferometry (combines the power of multiple telescopes into one) to directly observe HR8799e. The ‘super-Jupiter’ is believed to be home to a stormy atmosphere that rains silicate and iron particles.

It also isn’t the first time it was seen directly with telescopes. Here’s a video of the exoplanet system created by a series of images captured by the Keck Telescope.

The planet we’re talking about today (HR8799e) is the innermost one. The GRAVITY instrument on ESO’s Very Large Telescope (VLT) combined the power of VLT’s four telescopes to act as a single, large telescope, a technique called interferometry. Thanks to this instrument, astronomers could gather observations ten times more detailed than before.

Did you know: Interferometry is used often in radio astronomy. It’s why radio observatories usually consist of many separate satellite dishes. Astronomers use the technique to probe deep space. Optical interferometry is a little different because astronomers had to wait for the technology to improve to overcome obstacles like atmospheric turbulence. In VLT’s case, each telescope is equipped with an 8.2-meter primary mirror. But combine them with optical interferometry, and you get a telescope many times the power of a single telescope.

What does ten times more detail get you? Sylvestre Lacour, team leader for the researchers, explains: “Our analysis showed that HR8799e has an atmosphere containing far more carbon monoxide than methane – something not expected from equilibrium chemistry.”

HR8799e’s host star sits in the constellation of Pegasus. Credit: ESO

The best explanation Lacour and the other astronomers can come up with is the planet’s atmosphere is home to high vertical winds that stops the carbon monoxide from mixing with the hydrogen to create methane.

Lacour goes on to describe the planet’s harsh environment. “Our observations suggest a ball of gas illuminated from the interior, with rays of warm light swirling through stormy patches of dark clouds,” says Lacour. “Convection moves around the clouds of silicate and iron particles, which disaggregate and rain down into the interior. This paints a picture of a dynamic atmosphere of a giant exoplanet at birth, undergoing complex physical and chemical processes.”

These newest observations of HR8799e sound cool, but don’t expect any stunning pictures — just a lot of data. But the new technique will be handy at direct detection and spectroscopic study of exoplanets according to astronomers. For now, we’ll still be counting on artist concepts of what these distant worlds look like.

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