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An artistic representation 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
WITH-LED NASA mission finds a multi-planetary system that could be an “ideal laboratory” to study planetary formation and evolution.
MIT researchers have discovered four new exoplanets orbiting a sun-like star just over 200 light-years from Earth. Because of the diversity of these planets and the brightness of their star, this system could be an ideal target for atmospheric characterization with NASA’s upcoming James Webb space telescope. Tansu Daylan, a postdoctoral fellow at MIT Kavli Institute for Astrophysics and Space Research, led the study published in The Astronomical Journal on January 25, 2021.
With further research, Daylan says, this bright star and its many planets could be critical to understanding how planets take shape and evolve. “When it comes to characterizing planetary atmospheres around sun-like stars, this is probably one of the best goals we’ll ever get,” he said of the results presented earlier this month at the 237th meeting of the American Astronomical Society.
Transit method
Daylan and his colleagues detected these planets with the Transiting Exoplanet Survey Satellite (TESS), an MIT-led NASA mission. To identify exoplanets with TESS, researchers are looking for changes in the amount of light coming from a star. A small dip in a star’s light could mean a planet has passed in front of it, preventing some of its light from reaching Earth. By measuring these transits, scientists can estimate the size of a planet, how long it takes to orbit its star, and whether it has other planetary neighbors. In combination with other observation methods, such as measuring the gravitational effects a planet has on its host star, researchers can determine whether a planet is rocky or gaseous, warm or cold, and even whether it has a thick or thin atmosphere.
Like light from a distant star through the atmosphere of a exoplanet on the way to Earth, certain wavelengths of light will be absorbed by the gases in that atmosphere. When light reaches Earth, wavelengths of light corresponding to specific gases – such as water, carbon dioxide, or methane – will be missing, informing scientists of the composition of the atmosphere. This can provide astronomers with vital information about a planet’s environment, evolution and habitability. While TESS cannot characterize atmospheres, the telescope is key in identifying which exoplanets should be prioritized for atmospheric exploration by other higher-resolution telescopes, such as those from NASA. Hubble Space Telescope and the James Webb Space Telescope to be launched in the fall of 2021.
The locations of nearly 1,000 candidate exoplanets identified on September 1, 2019 are plotted on the TESS mosaic of the southern night sky. Credit: NASA / MIT / TESS and Ethan Kruse (USRA)
Using data from TESS and ground-based telescopes, Daylan determined that this star is home to a large, rocky inner planet, or super-Earth, and three outer gaseous planets that are just smaller than Neptune, known as sub-Neptune. Compared to our own solar system, these planets live very close to their sun; their jobs range from 19 days to just under four days. This makes them red-hot, their average surface temperatures range from 700 degrees Fahrenheit up to 1,500 F.
While this means that the planets are unlikely to harbor life, it gives astronomers much more data to work with; a short trajectory provides more frequent transits and thus more opportunities to examine the light that passes through the atmosphere. However, there may be undiscovered planets further along in this system, perhaps even in the star’s habitable zone. Recently, another research team used the characteristic Exoplanet Satellite (CHEOPS) to confirm a fifth planet, which takes 29 days to orbit the star.
The planets’ host star, TOI-1233, will provide ample light for future research, Daylan says. The star is similar in size and temperature to our own sun, but because it is relatively close to Earth, it appears very bright compared to other stars. In our opinion, it is the brightest known sun-like star and one of the brightest, harboring at least four continuous planets. This is useful, because a brighter star gives astronomers more light to work with in characterizing its planets.
Stars with many exoplanets are particularly exciting for astronomers, as they open new avenues for studying solar systems. “With multi-planetary systems you kind of hit the jackpot,” says Daylan. “The planets come from the same disk of matter around the same star, but they eventually become different planets with different atmospheres and different climates because of their different orbits. So we would like to understand the fundamental processes of planet formation and evolution using this planetary system, which acts as a controlled experiment. “
TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center. Additional partners include Northrop Grumman, located in Falls Church, Virginia; NASA’s Ames Research Center in Silicon Valley, California; the Center for Astrophysics – Harvard and Smithsonian in Cambridge; MIT Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide participate in the mission.
Read Four Exoplanets – Including a Super Earth – Discovered by High School Students to learn more about this discovery.
Reference: “TESS Discovery of a Super-Earth and Three Sub-Neptunes Hosted by the Bright, Sun-like Star HD 108236” by Tansu Daylan, Kartik Pinglé, Jasmine Wright, Maximilian N. Günther, Keivan G. Stassun, Stephen R. Kane, Andrew Vanderburg, Daniel Jontof-Hutter, Joseph E. Rodriguez, Avi Shporer, Chelsea X. Huang, Thomas Mikal-Evans, Mariona Badenas-Agusti, Karen A. Collins, Benjamin V. Rackham, Samuel N. Quinn, Ryan Cloutier , Kevin I. Collins, Pere Guerra, Eric LN Jensen, John F. Kielkopf, Bob Massey, Richard P. Schwarz, David Charbonneau, Jack J. Lissauer, Jonathan M. Irwin, Özgür Bastürk, Benjamin Fulton, Abderahmane Soubkiou, Benkhaldoun Zouhair , Steve B. Howell, Carl Ziegler, César Briceño, Nicholas Law, Andrew W. Mann, Nic Scott, Elise Furlan, David R. Ciardi, Rachel Matson, Coel Hellier, David R. Anderson, R. Paul Butler, Jeffrey D. Crane, Johanna K. Teske, Stephen A. Shectman, Martti H. Kristiansen, Ivan A. Terentev, Hans Martin Schwengeler, George R. Ricker, Roland Vanderspek, Sarah Seager, Joshua N. Winn, Jon M. Jenkins, Zachory K. Berta-Thompson, Luke G. Bouma, William Fong, Gabor Furesz, Christopher E. Henze, Edward H. Morgan, Elisa Quintana, Eric B. Ting and Joseph D. Twicken, January 25, 2021, The Astronomical Journal.
DOI: 10.3847 / 1538-3881 / abd73e