Astronomers from the Instituto de Astrofísica de Andalucía (IAA-CSIC) and the University of Granada have discovered a new planetary system, unique and key to understanding planetary formation processes: TOI-2096, composed of a “super-Earth” and a ‘mini’ -Neptune’ orbiting a nearby, cool star in a ‘synchronized dance’.

This finding was possible thanks to close collaboration between European and North American research centers and universities, led by the IAA-CSIC. The system was initially identified by NASA’s Transiting Exoplanet Survey Satellite (TESS), a space mission that searches for planets around bright nearby stars.

“TESS is conducting a sky-wide planet search using the transit method, i.e. monitoring the stellar brightness of thousands of nearby stars in anticipation of a slight dimming, which could be caused by a planet passing between the star and the Watcher. . However, despite its power to detect new worlds, the TESS mission needs the support of ground-based telescopes to confirm the planetary nature of the detected signals”, explains Francisco J. Pozuelos Romero, IAA-CSIC researcher and lead author of the article. recently published in the journal Astronomy & Astrophysics.

A very special setup

The planets TOI-2096 b (super-Earth) and TOI-2096 c (mini-Neptune) were observed with an international network of terrestrial telescopes, thus allowing their confirmation and characterization. “Performing an exhaustive analysis of the data, we discovered that the two planets were in resonant orbits, that is, for every two orbits of TOI-2096 b, TOI-2096 c makes one. “This configuration is very particular and due to it the planets interact strongly in a gravitational way, which allows us to obtain their masses, something we are currently doing with ultra-precise measurements with the 2.2-meter telescope at Calar Alto. Observatory”, says Pedro. J. Amado, researcher at the IAA-CSIC and co-author of the article.

The researchers estimate that TOI-2096 b’s radius is 1.2 times that of planet Earth (hence the name super-Earth). Likewise, the radius of TOI-2096 c is 55% smaller than that of Neptune (1.9 times the radius of Earth), so it is called ‘mini Neptune’. These sizes are really interesting because they could shed light on the anomaly known as Radio Valley, that is, the absence of exoplanets with radii between 1.5 and 2.5 Earth radii, something that is still not understood today.

The researchers who carried out this work. From left to right, Juan Carlos Suárez, Francisco J. Pozuelos and Pedro Amado.

IDEAL


“The size of these planets is of vital importance”, says Juan Carlos Suárez, a researcher at the University of Granada and also a co-author of the study. “Thanks to the global analysis of the data carried out on the high-performance computing servers of the University of Granada, we were able to understand that it is a truly unique system.” And he continues: «the formation of small planets, with less than 4 terrestrial radii, remains a mystery today. There are different models of planet formation trying to explain how planets with sizes between Earth and Neptune form, but none fit perfectly with the observations. TOI-2096 is the only system found to date that has a small planet, probably rocky, and a larger one of the right size where all the models contradict each other. In other words, TOI-2096 could be the Rosetta Stone we’ve been looking for to understand how planetary systems are formed.”

“Furthermore, these planets are among the best of their kind for studying their atmospheres,” says Francisco J. Pozuelos. “Thanks to the relative size of these planets and their stars, along with the star’s brightness, we found this system to be among the best to be analyzed in detail with the James Webb Space Telescope using the technique of transit spectroscopy, something we hope to do soon and for what we are coordinating with other universities and research centers. These studies will allow us to know more precisely how the system formed and, as we believe, the planet TOI-2096 c is an oceanic world, which would open up all a range of possibilities for future studies.”