Planet hunting satellite uncovers its first planet on Earth


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This is an artist's conception of HD 21749c, the first Earth-sized planet found by NASA's Exoplanet Research Satellite (TESS), as well as its brother, HD 21749b, a heated sub-Neptune-sized world. Illustration by Robin Dienel courtesy of the Carnegie Institution for Science

NASA's planet-hunting satellite, the Transition Exoplanet Research Satellite (TESS), has made a new discovery in the depths of space. Last month, TESS discovered its first exoplanet. And now it has reached another milestone, locating its first Earth-sized planet and a larger sister planet.

The Earth-sized planet, HD 21749c, and its brother orbit a star slightly smaller than our Sun, which is located 53 light-years from Earth. The HD 21749c is a rocky planet that orbits its star every eight days, which means it moves close to its star and has high surface temperatures of up to 800 degrees Fahrenheit.

"For stars that are very close and very bright, we expected to find up to a few dozen Earth-sized planets," said TESS author and member Diana Dragomir, a postdoctoral fellow at the Massachusetts Kavli Institute for Astrophysics and Space Research . , said in a statement. "And here we are – this would be our first and it is a milestone for TESS. It sets the way for finding smaller planets around even smaller stars, and these planets can be potentially habitable."

The larger planet is classified as a heated world of subneptune size, as well as a mass of about 23 times the mass of Earth and a radius of about 2.7 times that of Earth. Under the name HD 21749b, it is unusual for it to take 36 days to complete an orbit that is considerably longer than the 10-day orbital period that was expected for most of the planets the mission would find.

In order to find the planets, TESS sought a small decrease in the amount of light emitted by the host star, HD 21749, which occurred at regular intervals. This suggested that the star's light was being blocked by the transition of planets between it and Earth.

"It's so exciting that TESS, which was launched only a year ago, is already a watershed in the world's hunting business," said Johanna Teske of the Carnegie Institution for Science, the second author of the article, in a statement. "The spacecraft searches the sky and collaborates with the TESS monitoring community to identify potentially interesting targets for additional observations using telescopes and ground-based instruments."

The results are published in the journal Astrophysical Journal Letters.


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