Four New Exoplanets Discovered

An artist’s rendering of five planets orbiting TOI-1233, four of which were discovered using the Transiting Exoplanet Satellite Survey (TESS), an MIT-led NASA mission. Credit: NASA/JPL-Caltech

The discovery of four new exoplanets gives insight into how scientists search for habitable or previously inhabited exoplanets.

Exoplanets are just like the planets in our very own solar system, but with one key difference: They orbit around other stars instead of the Sun. Because exoplanets orbit bright stars, they are very difficult to detect with telescopes, so the discovery of an exoplanet is a very big deal.

MIT researchers recently discovered four new exoplanets. Tansu Daylan, a postdoc at the MIT Kavli Institute for Astrophysics and Space Research, published the discovery in The Astronomical Journal on January 25, 2021. The four new exoplanets were found 200 light-years away, orbiting a sun-like-star called TOI-1233 (one light-year is the same as 6 trillion miles, or 9 trillion kilometers).

One exoplanet was already known to orbit TOI-1233. The four new exoplanets were discovered using the transit method, in which astronomers look for a change in the amount of light that is coming from a star. A small momentary decrease in the amount of light coming from a star could indicate that a planet passed in front of it.

Studying the properties of this light can tell researchers a lot about the planet passing in front of the star. It can reveal the size of the planet, the length of the planet’s orbit, and whether there are other planets orbiting the same star.

The transit method can be combined with other investigative scientific methods to discover more about the exoplanet. Using the transit method while also measuring the planet’s gravitational effects on its star can tell researchers whether a planet is rocky or gaseous, hot or cold, and whether it has a thick or thin atmosphere.

The four new exoplanets were detected using the Transiting Exoplanet Survey Satellite (TESS). Using data from TESS, as well as data collected from ground-based telescopes, Daylan and his team were able to categorize the planets. One of the exoplanets is large and rocky, known as a super-Earth. The other three are outer planets and are gaseous. These gaseous planets are a bit smaller than Neptune, and are known as sub-Neptunes.

Multi-planetary systems like this one give insight into planet formation and evolution, especially because the planets orbiting the star are so different.

To analyze the four new exoplanets’ atmospheres and determine their molecular content, scientists will use atmospheric characterization with NASA’s James Webb Space Telescope (JSWT). JSWT is an orbiting infrared observatory that will complement the Hubble Space Telescope. The JSWT has longer wavelength coverage and is more sensitive than the Hubble Space Telescope, which makes it better at looking into dust clouds, which are where stars and planetary systems form.

Collecting data from exoplanets provides the key to understanding and investigating the diversity of planets in the universe. It also gives insight into the formation of planets. Furthermore, investigating exoplanets’ atmospheric properties contributes to the search and identification of habitable or already inhabited exoplanets.

This article was edited by Luka Austin and Lydia Guertin.