Researchers uncover pair of big ‘super-puff’ planets lighter than sweet floss

TOI-791 b and TOI-791 c have been first recognized as candidate planets in 2019 and 2023 respectively, by volunteers collaborating within the Planet Hunters TESS citizen-science mission. This searches information from NASA’s Transiting Exoplanet Survey Satellite (TESS) for doable new worlds. The researchers then measured the planets’ densities by combining observations of their sizes and lots more and plenty utilizing telescopes all over the world. 

When a planet passes in entrance of its host star – an occasion often known as a ‘transit’ – it barely dims the star’s mild. The quantity of dimming reveals the planet’s measurement. In this technique, the researchers additionally detected refined variations within the timing of the transits, attributable to the 2 planets gravitationally tugging on each other as they orbit the star. By analysing these timing shifts, the workforce was in a position to estimate the planets’ plenty and calculate their remarkably low densities.

The discovery relied on eight years of observations, together with from the ASTEP (Antarctic Search for Transiting ExoPlanets) telescope at Concordia Station in Antarctica, collectively operated by researchers from Université Côte d’Azur/Observatoire de la Côte d’Azur and worldwide collaborators. The Antarctic winter supplied a novel benefit: months of steady darkness enabled astronomers to seize the planets’ exceptionally lengthy transits, every lasting greater than 11 hours, in a single uninterrupted statement. These are the longest steady planetary transits ever noticed of their entirety from the bottom.

Astronomers are nonetheless debating how super-puff planets type. One leading theory means that they possess huge hydrogen- and helium-rich atmospheres that make up a major fraction of their complete mass. These big gaseous envelopes could have amassed when the planets shaped removed from their host star in chilly areas of the protoplanetary disc, the place fuel may cool and collect quickly round a strong core.

The researchers intend to hold out follow-up investigations to grasp extra about how these planets shaped, and to rule out among the main super-puff explanations.