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NASA’s Transiting Exoplanet Survey Satellite (TESS) spacecraft has found a second planet the same size as Earth. Photo/NASA/JPL-Caltech
NASA’s TESS spacecraft launched in April 2018 and discovered 285 confirmed exoplanets and more than 6,000 planet candidates. One of the more interesting confirmed planets is a world dubbed TOI 700 d, which is roughly the size of Earth and located in its star’s habitable zone.
Now, scientists have determined that the planet has an equally enticing neighbor. The planet was detected in October 2021 when Earth-orbiting telescopes spotted something of interest.
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“We saw it for the first time and we were like, ‘Is this true? Emily Gilbert, an astronomer at NASA’s Jet Propulsion Laboratory in California, told Space.com on Wednesday (1/11/2023). The results were presented at the 241st meeting of the American Astronomical Society, in Seattle and virtually on Sunday, January 8, 2023.
The TESS spacecraft found the planets by staring at the star for a month, looking for small dips in brightness that could indicate a planet passing between the star and the telescope. From this decrease, astronomers can estimate the planet’s size and its orbital hours.
In 2020, Gilbert and colleagues reported the discovery of three planets around a small star called TOI 700 (TOI stands for TESS Object of Interest), which is about 100 light-years from Earth. The star is a red dwarf, but unlike many of its siblings, TOI 700 is relatively quiet, with no sudden activity that could disrupt life on nearby worlds.
Two of the three planets that TESS originally discovered in the TOI 700 system were orbiting too close to their star to look like Earth. With just three planets, the scientists compared its system to TRAPPIST-1, a system 39.5 light-years away that is known to have seven Earth-sized planets.
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“It’s really a very interesting comparison,” Gilbert said. But the TOI 700 system will be easier to study, since TRAPPIST-1 is a more active and fainter star. “The TRAPPIST system is very dense; all the planets are very tight,” he continued.
Now, Gilbert and colleagues say the TOI 700 d has a more interesting third sibling. The planet, dubbed TOI 700 e, is not in what astronomers commonly call the habitable zone, but that definition is fluid.
Gilbert and his colleagues estimate TOI 700e to be about 95 percent the size of Earth, so it’s likely rocky and orbits every 28 Earth days. Newly discovered worlds are also likely tidally locked, always showing the same side of their stars.
(wib)
