A NASA spacecraft built to detect alien worlds has completed its first two years of work, and the tally is set: the mission carried 2,241 new ones. exoplanet candidates for scientists to study.
The transiting exoplanet study satellite (TESS) launched in April 2018, designed to spend two years perusing most of the sky. Each month, the spacecraft turns onto a new strip of stars and stares, observing the characteristic drops in brightness caused by a planet crossing between the star and the telescope. In a new catalog, astronomers offer a detailed look at a series of planet candidates that the spacecraft identified in its first two years of work.
“What’s exciting is looking at the TESS exoplanet map as a kind of to-do list, with 2,000 things on it,” Natalia Guerrero, a researcher at the Massachusetts Institute of Technology and lead author of the paper, said in a NASA statement.
Related: NASA’s planet-hunting TESS spacecraft captures a spectacular panorama of the Milky Way
To produce the new catalog, dozens of scientists pored over TESS observations of more than 16,000 targets to select planet candidates from other types of phenomena, finding 2,241 potential alien worlds.
The researchers also conducted initial tests to evaluate those candidate planets, detecting more than 500 other phenomena disguised as alien worlds, sometimes a phenomenon in space, sometimes a quirk produced by the activities of the spacecraft. (Astronomers write that scientists will likely find more false positives as they analyze the candidates in more detail.)
The first step for each so-called “object of interest” will be to confirm that the observations actually represent a planet, a process called planet confirmation. Confirming an exoplanet candidate it requires measuring both the size and mass of an object to be sure that it is actually a planet causing the signal, rather than some other phenomenon. Scientists have confirmed only 120 of the candidates described in the TESS catalog to date, according to the NASA statement, because the process requires instruments that are always quite busy.
That reality means that the catalog, despite being a body of work in itself, also represents a buffet of future scientific research. “It’s an incredible body of work – a rich pool of exoplanet candidates for the community to mine and explore for years to come,” said Jessie Christiansen, a research scientist at NASA’s Institute of Exoplanet Sciences and a co-author of the study, in the same statement.
Of all those possible new planets, a few stand out, of course, including the findings that represent the first for the mission. Pi Mensae c, for example, a sub-Neptune that can host a dense atmosphere, was the first discovery of the TESS mission. TOI 700 d it is the first planet identified by TESS that can be roughly the size of Earth and orbit in the habitable zone of its star.
Related: An Earth-sized planet in the habitable zone? NASA’s new discovery is a special world.
Other findings are intriguing in their own right. DS Tuc A b is almost six times the size of Earth and may only be 45 million years old. LHS 3844 b it does a full circuit of its star in just 11 hours, though it’s likely just a bare rock. TOI 1690 b can orbit a white dwarf, the dense core of a star that has lost most of its light elements.
TESS is still watching; NASA extended the mission for another two-year period, which will keep the spacecraft running until September 2022. And scientists will work with existing data, including the new catalog, for years to come.
“Now the role of the community is to connect the dots,” Guerrero said. “It’s really cool because the field is so young, there’s still a lot of room for discovery – those ‘Aha’ moments.”
The catalog is described in a paper Uploaded to the prepress server arXiv.org on March 23rd.
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