Roughly 100 light-years away, a world 95% the size of Earth orbits its star in the infinite void. The distant exoplanet, which lies in a habitable zone that allows liquid water to form on its surface, has existed in relative obscurity for NASA and its team of scientists, until now.
Exoplanet TOI 700 e, one of four planets found orbiting dwarf star TOI 700 in the southern constellation of Dorado, has been detected by NASA’s Transiting Exoplanet Survey Satellite (TESS).
“One of the primary goals of TESS is to be what people have been calling a finder scope for the JWST (James Webb Space Telescope), so it’s effective for detecting planets that we think would be good targets for characterizing their atmospheres,” Emily Gilbert, a postdoctoral fellow in the JWST lab. Jet Propulsion that led the work to find TOI 700 e. “TESS is looking at the nearest brighter stars, looking for targets that we think are more trackable.”
TESS detects exoplanets by observing large areas of the sky for about 27 days at a time, allowing the satellite to track changes in stellar brightness caused by planet transits, as it moves in front of its star.
“TOI 700 e’s signal was originally captured by the TESS planet search pipeline,” Gilbert explained. “These signs can include a lot of false positives and other non-planetary things, so once you have that suggested sign you have to go in and make sure it’s ‘real’ and confirm it and craft the data.” Once you do that, you can select quite a few characteristics of the planet. Then you can use that to learn more about the planet, find out its size, learn about its orbit and put it in the context of the system and in the context of all the exoplanets that we know about.”
The mission had previously discovered the other three planets in the TOI 700 system. TOI 700 b is about 90% the size of Earth and orbits the star every 10 days. TOI 700 c is 2.5 times larger than Earth and rotates every 16 days, while TOI 700 d is the size of Earth and joins TOI 700 e in the habitable zone.
“Having multiple planets in the habitable zone allows us to compare some of these characteristics (such as temperature and size) and see what we think might be really important to a planet’s habitability,” Gilbert said. “There are only a few other systems out there like this and it’s really hard to keep track of a lot of them. That’s really exciting for me.”
Gilbert hopes her team can extend their existing data on the TOI 700 system to include measurements of the star’s radial velocity, which can be used to calculate planetary masses. Knowing the mass and radius, Gilbert’s team can find the composition of each planet.
“There are a lot of people who have worked on projects like this; it’s really a great collaborative effort,” Gilbert said. “We have some people who spend a lot of time on data reduction and modeling and all the pipelines from TESS…even just building the TESS spacecraft and all the infrastructure required for that. On top of that, we have observer people on the ground who contribute to the follow-up that we use as part of the TESS follow-up and monitoring program called TFOP.
“You’ll see in any of the big TESS discovery papers, the author lists have dozens of authors because it really takes an entire community to confirm these planets.”
Gilbert insisted that this discovery would become one of many more significant discoveries as TESS slowly fills in previously unnoticed patches of sky. She described the rush of new internal discoveries and external interest as “overwhelming”.
“I love seeing all the news that comes out on this topic,” Gilbert said. “A lot of times your research isn’t something that interests the general public. To see people who aren’t astronomers really excited about this discovery as well, it’s really amazing.”