NASA's new Planet Hunter finds its first earthly world and is "potentially habitable"

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A world the size of the Earth was discovered in a star system 53 light years from our solar system just days after a study revealed that life could exist on four & nbsp; exoplanets close.

The first Earth-size planet discovered using NASA's Transiting Exoplanets Survey Satellite (TESS) was found in orbit around a star and a planet larger and warmer than Neptune's . "This is an important step for TESS," said Diana Dragomir, exoplanetologist at MIT Kavli Institute and lead author of "TESS delivers its first planet the size of the Earth and a warm sub-Neptune", published in Astrophysical Journal Letters. "This paves the way for finding small planets around even smaller stars, and these planets can potentially be habitable." & Nbsp; This is the 10th confirmed planet discovered by TESS.

What did astronomers find?

Orbiting the dwarf star K HD 21749, astronomers have discovered the HD 21749c, which takes about eight days to orbit around the host star and whose size is similar to that of the Earth, with 89% of its diameter. Probably a rocky world, it is thought that its surface temperature can reach 800& deg;F / 427& deg; C. & nbsp; They also discovered the HD 21749b, a hot world the size of 20 to 23 times the land mass and about 2.7 times the radius of the Earth, which revolves around its star host every 36 days. This one was a little surprising since TESS is not designed to detect planets that take more than 10 days to revolve around their star.

What is TESS?

Launched at the top of a SpaceX Falcon 9 rocket on April 18, 2018, TESS is a planet-hunting spacecraft designed to search for planets similar to Earth. TESS will observe 400,000 stars across the sky to glimpse a planet in transit across the face of its star. TESS will also allow astronomers to measure for the first time the masses, atmospheric compositions and other properties of many smaller exoplanets.

To find the HD 21749c, astronomers detected 11 periodic declines in star brightness to determine that its light was partially blocked by a planet the size of the Earth.

Why is TESS changing the game?

"It's so exciting that TESS is already making a difference in the global hunting industry," said Johanna Teske, researcher at the Carnegie Institution for Science and second author of the journal. "The probe observed the sky and we collaborated with the TESS tracking community to identify potentially interesting targets for additional observations using telescopes and ground instruments." Several astronomers from the Carnegie Institution for Science also participated in the document, namely Paul Butler, Steve Shectman, Jeff Crane and Sharon Wang.

Which terrestrial telescope was used?

TESS is designed to make a short list of targets for large space and ground telescopes to explore. In this case, Magellan II, a 6.5-meter telescope at the Las Campanas de Carnegie Observatory in Chile, was used to track TESS data. It hosts the Planet Finder Spectrograph (PFS), a tool built by Shectman and Crane using a method developed by Butler and his collaborators, which confirmed that the TESS signal was indeed a planet. It was also used to measure the mass of the HD 21749b, which looks like Neptune, which was not possible for the much smaller HD 21749c. At least not yet.

How do you measure the mass of an exoplanet?

Flickering orbits. The mass of a planet is important to help astronomers know more about its density and chemical composition. The PFS tool uses the "radial velocity" technique, which detects not only the minute oscillations of a planet's orbit, caused by the gravity of the host star, but also the effect of the gravity of the planet. on the orbit of the star. "The PFS is one of the only instruments in the southern hemisphere that can do this type of measurement," said Teske. "This will be a very important part of the subsequent characterization of the planets found by the TESS mission."

What will astronomers do next?

Potentially, the first mass measure of a planet the size of the Earth found by TESS. "Measuring the exact mass and composition of such a small planet will be a challenge, but it is important to compare the HD 21749c to the Earth," Wang said. "The Carnegie PFS team continues to collect data on this object for this purpose."

Will TESS help find more planets the size of the Earth?

Scheduled to last at least two years and for a decade, TESS should find more than 20,000 exoplanets, hopefully, many sizes similar to those of the Earth. "For very close and very bright stars, we expected to find up to twenty planets the size of the Earth," said Dragomir. "And here we are – it would be our first, and it's an important step for TESS."

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A world-sized Earth was discovered in a star system 53 light-years from our solar system just days after a study revealed that life could exist on four nearby exoplanets.

The first Earth-size planet discovered using NASA's Transiting Exoplanets Survey Satellite (TESS) was found in orbit around a star and a planet larger and warmer than Neptune's . "This is an important step for TESS," said Diana Dragomir, exoplanetologist at the MIT Kavli Institute and senior author of "TESS delivers its first planet the size of a planet and a warm sub-Neptune," published in Astrophysical Journal Letters. to find smaller planets around even smaller stars, and these planets can potentially be habitable. This is the 10th confirmed planet discovered by TESS.

What did astronomers find?

Orbiting the dwarf star K HD 21749, astronomers have discovered the HD 21749c, which takes about eight days to orbit around the host star and whose size is similar to that of the Earth, with 89% of its diameter. Probably a rocky world, it is thought that its surface temperature can reach 800°F / 427° C. They also discovered the HD 21749b, a warm world the size of a size smaller than Neptune, about 23 times the mass of the Earth and a radius of about 2.7 times that of Earth, which revolves around from its star host every 36 days. This one was a little surprising since TESS is not designed to detect planets that take more than 10 days to revolve around their star.

What is TESS?

Launched at the top of a SpaceX Falcon 9 rocket on April 18, 2018, TESS is a planet-hunting spacecraft designed to search for planets similar to Earth. TESS will observe 400,000 stars across the sky to glimpse a planet in transit across the face of its star. TESS will also allow astronomers to measure for the first time the masses, atmospheric compositions and other properties of many smaller exoplanets.

To find the HD 21749c, astronomers detected 11 periodic declines in star brightness to determine that its light was partially blocked by a planet the size of the Earth.

Why is TESS changing the game?

"It's so exciting that TESS is already making a difference in the global hunting industry," said Johanna Teske, researcher at the Carnegie Institution for Science and second author of the journal. "The probe observed the sky and we collaborated with the TESS tracking community to identify potentially interesting targets for additional observations using telescopes and ground instruments." Several astronomers from the Carnegie Institution for Science also participated in the document, namely Paul Butler, Steve Shectman, Jeff Crane and Sharon Wang.

Which terrestrial telescope was used?

TESS is designed to make a short list of targets for large space and ground telescopes to explore. In this case, Magellan II, a 6.5-meter telescope at the Las Campanas de Carnegie Observatory in Chile, was used to track TESS data. It hosts the Planet Finder Spectrograph (PFS), a tool built by Shectman and Crane using a method developed by Butler and his collaborators, which confirmed that the TESS signal was indeed a planet. It was also used to measure the mass of the HD 21749b, which looks like Neptune, which was not possible for the much smaller HD 21749c. At least not yet.

How do you measure the mass of an exoplanet?

Flickering orbits. The mass of a planet is important to help astronomers know more about its density and chemical composition. The PFS tool uses the "radial velocity" technique, which detects not only the minute oscillations of a planet's orbit, caused by the gravity of the host star, but also the effect of the gravity of the planet. on the orbit of the star. "The PFS is one of the only instruments in the southern hemisphere that can do this type of measurement," said Teske. "This will be a very important part of the subsequent characterization of the planets found by the TESS mission."

What will astronomers do next?

Potentially, the first mass measure of a planet the size of the Earth found by TESS. "Measuring the exact mass and composition of such a small planet will be a challenge, but it is important to compare the HD 21749c to the Earth," Wang said. "The Carnegie PFS team continues to collect data on this object for this purpose."

Will TESS help find more planets the size of the Earth?

Scheduled to last at least two years and for a decade, TESS should find more than 20,000 exoplanets, hopefully, many sizes similar to those of the Earth. "For very close and very bright stars, we expected to find up to twenty planets the size of the Earth," said Dragomir. "And here we are – it would be our first, and it's an important step for TESS."