Artist’s concept of TIC 172900988b, the first circumbinary planet found by TESS. Image via Pamela Gay/ Planetary Science Institute.
TESS’s planet orbiting 2 stars
Astronomers announced this month (November 10, 2021) that the space-based TESS planet-hunter (Transiting Exoplanet Survey Satellite) has discovered its first exoplanet orbiting two stars. It’s a gas giant planet, almost exactly the same size as our solar system’s biggest world, Jupiter. But it’s about three times more massive than Jupiter. And it’s 818 light-years from Earth, in contrast to Jupiter’s distance of less than a light-hour.
The newly found planet is called TIC 172900988b. It orbits its dual host stars in only 200.5 Earth-days (Jupiter takes 12 Earth-years to orbit our sun once). The discovery is significant to scientists because it demonstrated it was possible to detect TIC 172900988b, a circumbinary star, with a limited amount of data. The scientists observed as the planet transited its primary star, then transited its secondary star five days later. The two stars underwent an eclipse of each other, too, over a 20-day orbit. The scientists said in a statement:
Previous detections of circumbinary planets required observing three transits which was not possible in the short observation window.