Very Large Telescope Gears Up to Hunt Exoplanets in Alpha Centauri

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Astronomers around the world were thrilled in 2016 when the European Southern Observatory announced the discovery of an exoplanet around Proxima Centauri, the closest star to Earth. The Centauri system contains a few more stars, though. Now, the Very Large Telescope (VLT) has gotten an upgrade that will help it scan those other stars for evidence of exoplanets.

Proxima Centauri is a red dwarf star just 4.2 light years from Earth. Alpha Centauri consists of two larger stars around 4.37 light years from Earth. Centauri A is a bit larger and brighter than the sun, and Centauri B is smaller and cooler. While the exoplanet around Proxima Centauri is in the star’s “habitable zone,” the red dwarf is very different from ours. Many scientists believe that radiation and solar flares from Proxima Centauri would make life on Proxima Centauri b impossible. That might not be the case for planets that may exist around Alpha Centauri A and B.

The VLT, a network of four eight-meter telescopes in Chile, already had the ability to observe the universe in the mid-infrared wavelengths. It’s joining the exoplanet hunt with the addition of an instrument called NEAR (Near Earths in the AlphaCen Region) that makes it much more sensitive.

Planets orbiting nearby stars are theoretically easier to find, but the light from Centauri A and B make the comparatively faint light of a planet invisible. NEAR is essentially an infrared coronograph that filters out the light from a star, leaving only the light from other objects in a solar system. This differs from traditional ways of detecting exoplanets, which rely on analyzing their gravitational effects on a star or dimming of starlight as planets pass in front of it. NEAR could capture real images of an exoplanet.

eso exoplanet

This artist’s impression shows the planet Proxima b orbiting in the Goldilocks zone around the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Image: ESO

The European Southern Observatory, which operates the VLT, believes NEAR will be sensitive enough to detect small rocky planet about twice as large as Earth. Most of the exoplanets astronomers have detected are much larger, but Alpha Centauri is a great place to look for smaller ones because it’s so close. It’s not going to be smooth sailing all the way, though. Alpha Centauri is a binary system. We don’t know how planetary systems work around binary stars, or if they exist at all.

The NEAR system completed its first observational run earlier this month. Now, it’s up to scientists to examine the data to see if it spotted any signs of exoplanets around either star.

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