Thanks to a particularly favorable constellation, the TESS space telescope has found an exoplanet that orbits two stars at the same time and takes 200 days to do so. The device was not actually designed to detect exoplanets with long orbital times; After all, it only looks for small darknesses in stars in an area of the sky for a few days, indicating transiting planets. To confirm the orbit, however, at least two dimming states are required. Since exoplanet TIC 172900988 b passes in its orbit in front of two central stars in its system from our perspective, the transit of stars and the transit of an exoplanet in front of them can be observed. That was enough for the calculation.
Little data for complex calculations
As NASA now explains,, TIC 172900988 b is a gas giant the size of Jupiter orbiting two stars similar to the Sun. A number of exoplanets orbiting two stars are already known, but with their very wide orbit they stand out among this group. The calculation of the orbit data is very complicated in such a case, among other things because one would have to wait 200 days for the orbit confirmation. This will not be possible with TESS, because the space telescope examines the starry sky sector by sector, not for a very long time. The discovery was possible only thanks to the structure of the system and the convenient location of the stars and exoplanets. This was the first time ever that such complex orbital motions had been calculated with so little data. There is also a hint of another star orbiting all three.
The Transiting Exoplanet Reconnaissance Satellite (TESS) is a successor to the successful exoplanet hunter Kepler and has been in space since 2018. It has already discovered thousands of potential exoplanets on its primary mission, but not all of them have been confirmed yet. The instrument focuses on a region of the sky that is 24 degrees by 96 degrees for at least 27 days and scans the stars in it for periodic shading that indicates exoplanets. For the necessary transients, they have to orbit their star in a few days, so those found this way bring it much closer than Kepler discovered. However, it is also possible to find darkness in two different observations of the same area. Of the 169 confirmed TESS discoveries, ten of which have orbits greater than 30 days, only TIC 172900988 b reaches more than 100.
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