An Earth-sized planet has been discovered 100 light-years from the solar system. Scientists’ attention was drawn to the fact that its orbit is inside a potentially habitable zone. Interestingly, this is not the only “cousin” of the Earth in this system – another celestial body with appropriate dimensions and location was discovered earlier.
Observing Earth-like exoplanets – planets orbiting a star other than the Sun – is no easy task. Due to the relatively small dimensions of these celestial bodies, measuring instruments often have trouble seeing them. This was the case with the newly discovered TOI 700 e, which was only observed a year after the other planets were found in its system. As indicated NASAbut it was worth the wait.
A year lasts 28 days
Using data from NASA’s Transiting Exoplanet Survey (TESS) satellite, scientists have identified an exoplanet not much smaller than Earth in the TOI 700 system, most likely rocky. Interestingly, it orbits within the habitable zone – a potentially habitable zone around a star where liquid water may exist on the surface of a celestial body.
TOI 700 is a cool red dwarf about 100 light-years from Earth in the constellation of Golden Fish. Previously, researchers had identified three other planets in this system: TOI 700 b, c and d, but due to the small size of the celestial body, they needed an additional year of observation to discover TOI 700 e.
“If the star was a little closer, or the planet a little bigger, maybe we could see TOI 700 e in TESS’s first year,” explained Ben Hord of the University of Maryland. “However, the signal was so weak that we needed an extra year of observation to identify it.”
The exoplanet most likely rotates synchronously, meaning that it is constantly facing the star with the same hemisphere. It takes 28 days for one complete revolution – slightly less than the neighboring, Earth-like TOI 700 d. Scientists suspect that the chances of water on the surface of TOI 700 e are slightly lower than on planet d, but it is possible that at some point in history celestial body there could be reservoirs of liquid water on it.
Planet TOI 700 e – artist’s vision. In the background is another “cousin” of Earth, TOI 700 dNASA/JPL-Caltech/Robert Hurt
Unique worlds
“This is one of the few known systems with many small planets within the habitable zone,” explains Emily Gilbert of NASA’s Jet Propulsion Laboratory, lead author of the study. – Planet e is about 10 percent smaller than planet d, which shows how additional TESS observations are helping us find increasingly smaller worlds.
The TESS satellite monitors large sectors of the sky for about 27 days. This allows us to track changes in the brightness of stars caused by planets passing in front of their faces, what we call transits. This is one of the main ways to observe exoplanets.
Gilbert adds that the study of the TOI 700 system with space and ground-based observatories is ongoing and may yield further insights into extrasolar planets. Finding other planetary systems with Earth-sized worlds will help scientists learn more about the history of the solar system.
Main photo source: NASA/JPL-Caltech/Robert Hurt