Starship Asterisk*

An artist's rendering of a five-planet system around TOI-1233 includes a super-Earth (foreground) that could help solve mysteries of planet formation. The four innermost planets were discovered by high schoolers Kartik Pinglé and Jasmine Wright alongside researcher Tansu Daylan. The fifth outermost planet pictured was recently discovered by a separate team of astronomers. Credit: NASA/JPL-Caltech

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This week, 16-year-old Kartik Pinglé and 18-year-old Jasmine Wright have co-authored a peer-reviewed paper in the Astronomical Journal describing the discovery of four new exoplanets about 200-light-years away from Earth.

The high schoolers participated in the research through the Student Research Mentoring Program (SRMP) at the Center for Astrophysics | Harvard & Smithsonian. Directed by astrochemist Clara Sousa-Silva, the SRMP connects local high schoolers who are interested in research with real-world scientists at Harvard and MIT. The students then work with their mentors on a year-long research project. ...

With guidance from mentor Tansu Daylan, a postdoc at the MIT Kavli Institute for Astrophysics and Space Research, the students studied and analyzed data from the Transiting Exoplanet Survey Satellite (TESS). TESS is a space-based satellite that orbits around Earth and surveys nearby bright stars with the ultimate goal of discovering new planets.

The team focused on TESS Object of Interest (TOI) 1233, a nearby, bright Sun-like star. To perceive if planets were rotating around the star, they narrowed in on TOI-1233’s light. ...

To the team’s surprise, they discovered not one but four planets rotating around TOI-1233. ...

Three of the planets are considered "sub-Neptunes," gaseous planets that are smaller than, but similar to our own solar system’s Neptune. It takes between 6 and 19.5 days for each of them to orbit around TOI-1233. The fourth planet is labeled a "super-Earth" for its large size and rockiness; it orbits around the star in just under four days. ...

• Astronomical Journal 161(2):85 (Feb 2021) DOI: 10.3847/1538-3881/abd73e
• arXiv.org > astro-ph > arXiv:2004.11314 > 23 Apr 2020 (v1), 05 Jan 2021 (v2)

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The team found the four-planet system when examining HD 108236 – aka. TESS Object of Interest 1233 (TOI -1233) – a G-type (yellow dwarf) star located 210 light-years from Earth. After combining TESS transit data with reconnaissance, Doppler spectroscopy, and high-resolution imaging from ground-based telescopes, they determined that a system of no less than four planets orbited this star.

These include a large, rocky inner planet (aka. a super-Earth) and three gaseous outer planets that are slightly smaller than Neptune (mini-Neptunes). Compared to the Solar System, all five planets orbit very closely to their Sun – ranging from 0.046 AU to 0.14 (4.6 to 14% the distance between Earth and the Sun) – and have orbital periods of just under four days to nineteen and a half.

As a result, Daylan and his team estimate that they experience surface temperatures ranging from 370 to 815 °C (700 to 1,500 °F). A day later, another international team announced the discovery of a fifth exoplanet using data from the ESA’s CHaracterising Exoplanet Satellite (CHEOPS). This planet is another Super-Earth that orbits rather closely to its parent star (0.17 AU) and has orbital period of 29 days. ...