Now that TESS is Operational, Astronomers Estimate it’ll Find 14,000 Planets. 10 Could Be Earthlike Worlds in a Sunlike Star’s Habitable Zone

A new study from Thomas Barclay of NASA and the University of Maryland, Joshua Pepper at Lehigh University, and Elisa Quintana of NASA, has predicted TESS’s results. Barclay, Pepper, and Quintana ran their simulation 300 times to come up with their predicted yield. There’s a lot of detail in their results related to the type of star the planets orbit, the different observation mode used to detect which planets, and how it all relates to follow-up observations. But in a more brief form, here’s what the three researchers think TESS will find during its planned two-year mission:
  • 14,000 total exoplanets
  • 2100 of them will be smaller than 4 Earth radius (4R), 280 of those smaller than 2R
  • 70 habitable planets orbiting red dwarf stars, 9 of them smaller than 2R
  • 10 Earth-like worlds less than 2R which could be in the habitable zone of a star like our Sun
That’s a pretty exciting haul. 14,000 exoplanets, of which 10 could be Earth-like worlds in the habitable zone of a star like the Sun. It doesn’t mean that’s what TESS will find, but it should be a good approximation, and an intriguing one. Especially since, unlike Kepler, TESS’s exoplanets are prime targets for further observation and characterization.

Most exoplanets orbit red dwarf stars because they're the most plentiful stars. This is an artist's illustration of what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (at right). Credits: NASA/JPL-Caltech
Most exoplanets orbit red dwarf stars because they’re the most plentiful stars. This is an artist’s illustration of what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (at right). Credits: NASA/JPL-Caltech

This isn’t the first yield simulation for TESS. But this one is done with real rather than simulated stellar population, so it should be more accurate. Another yield simulation from 2015 can be viewed here, and one from 2017 here.
The simulation yields show us that we’re likely to find Earth-like planets in habitable zones. Most of them will be orbiting red dwarfs, but a small number should be around Sun-like stars. This is what everybody wants to know.
But maybe more importantly, these simulations show us that TESS will meet its mission goal: to detect an abundance of planets smaller than Neptune that can be examined in follow up studies to determine their masses and atmospheric makeups.
In both cases, TESS is on track to deliver some solid results.