Second potentially habitable Earth-sized planet found orbiting a nearby star

Second potentially habitable Earth-sized planet found orbiting a nearby star

Second potentially habitable Earth-sized planet found orbiting a nearby star

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A NASA mission has spotted an Earth-sized exoplanet orbiting a small star about 100 light-years away.

The planet, called TOI 700 e, is likely rocky and 95% the size of our world. The celestial body is the fourth planet to be detected orbiting the small, cool M dwarf star TOI 700. the exoplanets were found by NASA’s Transiting Exoplanet Survey Satellite, or TESS mission.

Another planet in the system, discovered in 2020 and named TOI 700 d, is also the size of Earth. Both exoplanets are in their star’s habitable zone, or just the right distance from the star that liquid water could potentially exist on their surfaces. The potential for liquid water suggests that the planets themselves could be, or once were, habitable for life.

The discovery of the fourth planet was announced Tuesday at the 241st meeting of the American Astronomical Association in Seattle, and a study on the exoplanet has been accepted for publication by The Astrophysical Journal Letters.

“This is one of the few systems with multiple, minor planets with a habitable zone that we know of,” lead study author Emily Gilbert, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said in a statement.

“That makes the TOI 700 system an exciting prospect for additional follow-up. Planet e is about 10% smaller than planet d, so the system also shows how additional TESS observations help us find increasingly smaller worlds.”

Small, cool M dwarf stars like TOI 700 are common in the Universe, and in recent years many have been found to host exoplanets, such as the TRAPPIST-1 system and its seven exoplanets which the James Webb Space Telescope will observe.

Closest to the star is TOI 700 b, which is 90% the size of Earth and completes a fast orbit around the star every 10 Earth days. Then there’s TOI 700 c, which is 2.5 times larger than our planet and completes an orbit around the star every 16 days. These planets are both likely to be tidally closed, meaning they always show the same side to the star – much like how the same side of the moon always faces Earth.

The two exoplanets in the star’s habitable zone, planets d and e, have longer orbits of 37 days and 28 days, respectively, because they are slightly further from the star. The newly announced planet e is actually between planets c and d.

Launched in 2018, the TESS mission will monitor large swaths of the night sky for 27 days, gazing at the brightest stars and tracking their changes in brightness. These dips in brightness indicate planets orbiting Earth as they pass in front of their stars, called transits. The mission began observing the southern sky in 2018 and then focused on the northern sky. In 2020, the mission refocused on the southern sky for additional observations, revealing the fourth planet in the TOI 700 system.

“If the star was a bit closer or the planet a bit bigger, we might have seen TOI 700 e in the first year of TESS data,” said study co-author Ben Hord, a doctoral student at the University of Maryland, College Park. , and a graduate researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in a statement. “But the signal was so weak that we needed the extra year of transit observations to identify it.”

As the researchers use other space and ground-based observatories to conduct follow-up observations of the intriguing planetary system, more TESS data is pouring in.

“TESS has just completed its second year of observing the northern sky,” said Allison Youngblood, a research astrophysicist and TESS’ deputy project scientist at Goddard. “We look forward to the other exciting discoveries hidden in the mission’s wealth of data.”

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