A system of four planets orbiting the star TOI-500

An international team of astronomers has located a new planetary system of four planets orbiting the star TOI-500. This is the first known system composed of an Earth analogue, with an ultrashort period of less than one day, and three additional low-mass planets, whose orbital configuration could be explained by a non-violent and smooth migration scenario. The study is published in the journal Nature Astronomy.

The inner planet, named TOI-500b, it is an ultra-short period (USP) planet, as its orbital period is only 13 hours. It is considered an analog of Earth, that is, a rocky planet with radius, mass and density comparable to ours.

“However, unlike Earth, its proximity to the star makes it so hot (about 1,350°C) that its surface is probably a vast expanse of lava.”it states Luisa Maria Serrano, researcher at the Physics Department of the University of Turin and first author of the article. The new planet could be a true reflection of what Earth will look like in the future, when the Sun becomes a red giant much larger and brighter than it is now.

four planet system

TOI-500b was initially identified as a planet candidate by the Transiting Exoplanet Survey Satellite (TESS) NASA, a space telescope designed to search for planets in orbit around nearby bright stars using the transit method. This method measures the dimming of a star’s brightness as the planet crosses the stellar disk as seen from the telescope.

The terrestrial analog planet was later confirmed thanks to a year-long observation campaign carried out by the University of Turin with the HARPS spectrograph of the European Southern Observatory (ESO).

Analysis of the TESS and HARPS data has provided precise measurements of the mass, radius, and orbital parameters of the ultrashort period inner planet TOI-500b. “HARPS measurements have also allowed us to detect 3 additional low-mass planets orbiting TOI-500 every 6.6, 26.2 and 61.3 days. TOI-500 is an extraordinary planetary system, important for understanding the dynamic fate of the planets”says Davide Gandolfi, a researcher at the Physics Department of the University of Turin and co-author of the article.

novel migration

The novelty presented by the recently published article lies in the migration process that brought the planetary system to its current configuration. “It is commonly accepted that ultra short period planets they did not form in their current orbits, as the innermost regions of their natal protoplanetary disk are of inadequate density and temperature to form planets, so they must have originated further out and then migrated inward, closer to their host star ”it states Hans J. Deeg, researcher at the Institute of Astrophysics of the Canary Islands (IAC) who has participated in the study.

Although there is no consensus on the migration process, it is often believed to occur through a violent process, involving the deflection of one planet from its orbit by interaction with another. However, the researchers believe that the planets orbiting TOI-500 may have always been in nearly circular orbits and then migrated inwards following a slow, nonviolent migration process that lasted about 2 billion years.

Silent migration pattern

“It is a silent migration pattern, in which the planets move slowly in orbits closer and closer to their star, without colliding with each other and without leaving their orbits”explains another of the authors Philip Murgas, IAC researcher.

“This work demonstrates the importance of linking the discovery of systems that host ultrashort period planets with numerical simulations to verify the possible migratory processes that may have led them to their current orbital configuration”Add Enric Palle, also co-author and IAC scientist. “The acquisition of data over a long time baseline allows us to reveal the internal architecture of systems similar to TOI-500 and understand how the planets have settled in their orbits”he concludes.

Font: IAC, SINC Agency,

Reference article: https://www.agenciasinc.es/Noticias/Un-sistema-de-cuatro-planetas-con-un-peculiar-proceso-migratorio