TESS Discovered An Exoplanet Very Similar to Earth

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It appears that TESS (the Transiting Exoplanets Survey Satellite) has already made its first significant discovery. An Earth-sized planet was found in a system close to ours. A sub-Neptune world was also discovered there.

“For stars that are very close by and very bright, we expected to find up to a couple of dozen Earth-sized planets. And here we are–this would be our first one, and it’s a milestone for TESS. It sets the path for finding smaller planets around even smaller stars, and those planets may potentially be habitable,” explained Diana Dragomir from the MIT’s Kavli Institute for Astrophysics and Space Research.

A paper was already published in Astrophysical Journal Letters. The team of astronomers behind it includes Johanna Teske, Paul Butler, Steve Shectman, Jeff Crane, and Sharon Wang.

“It’s so exciting that TESS, which launched just about a year ago, is already a game-changer in the planet-hunting business,” said Teske. “The spacecraft surveys the sky, and we collaborate with the TESS follow-up community to flag potentially interesting targets for additional observations using ground-based telescopes and instruments.”

TESS spotted an exoplanet just like Earth

In order to make this discovery, one crucial tool was used, the Planet Finder Spectrograph on the Magellan II telescope at Carnegie’s Las Campanas Observatory in Chile. The PFS was built using the radial velocity method which allows astronomers to measure the masses of planets.

“PFS is one of the only instruments in the Southern Hemisphere that can do these types of measurements,” Teske added. “So, it will be a very important part of further characterizing the planets found by the TESS mission.”

HD 21749c is the Earth-sized planet discovered in this system, but researchers believe that it won’t be simple to measure the exact mass of this planet.

“Measuring the exact mass and composition of such a small planet will be challenging, but important for comparing HD 21749c to Earth,” said Wang. “Carnegie’s PFS team is continuing to collect data on this object with this goal in mind.”


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