With Ariel at the origin of the properties of the planets (Planetary Science)

A study led by astrophysicist Diego Turrini of the National Institute of Astrophysics illustrates the role that future observations of the Ariel Space Telescope can play in understanding how the planetary formation process and the interaction between young planets and the surrounding environment can shape the final properties of exoplanets

To date, the number of confirmed exoplanets ( more than 4500 ) is such as to allow not only studies dedicated to individual planets and their systems, but also detailed population analyzes. These are essential for understanding the planetary formation process, the evolution of planets, the chemical composition and physical properties of exoplanetary atmospheres, and how all of this is affected by the surrounding environment and the properties of the star around which the planets orbit. The chemical analysis of the atmospheres of a rich sample of exoplanets is the main objective of Ariel , the M4 class mission of the European Space Agency, whose launch is scheduled for 2029.

During his mission, Ariel will provide detailed observations of the chemical composition of the atmospheres of hundreds of exoplanets, mainly gas-type planets. This will not only revolutionize our knowledge of the individual planets that will be observed, but will provide for the first time important measurements of chemical abundances for a rich and diverse sample of exoplanets. In particular, one of the working groups made up of astronomers involved in the project, and led by the astronomer Diego Turriniof the National Institute of Astrophysics, aims to understand how the planetary formation process and the interaction between young planets and the surrounding environment can shape the final properties of the planets. The importance of the environment and migration processes in sculpting the properties of planets, and the role that Ariel’s observations will play in the study of these processes, are described in an article by Turrini and colleagues published on October 15 in  Experimental Astronomy. .

«The planetary composition», Turrini explains to Media Inaf, «It has always been one of the most powerful investigative tools we have for scrutinizing the planets’ past and unraveling the mystery of how they were born. To effectively exploit this tool, however, it is essential to look at each planet in the context of the environment in which it was born and evolved and to take into account all the factors that may have influenced the path that led it to become as we see it today. The key aspect of our study is precisely this: to identify the environmental factors that shape the planets and the signatures they leave in their compositional and orbital characteristics, starting with how the galactic environment influences star formation to how the latter portrays it. scenario in which planetary formation takes place,

Diego Turrini, researcher at INAF in Rome and Turin © INAF

The planets, in fact, are formed in disks of gas and dust called protoplanetary disks, observed around very young stars, and whose evolution and chemical properties can be influenced by the stellar environment in which they are found. Furthermore, the physico-chemical properties of the disks change drastically with the distance from the central star. This is particularly important since, during the early evolutionary phases of exoplanetary systems, migration phenomena of planets in different orbits are common. During these migrations, planets can grow material from the disk and other planetesimals (rocky objects that make up the embryos of planetary formation) with different chemical compositions and physical properties, and this can affect the final properties of the planets and their atmospheres. In the end,

“Understanding the role of these factors is critically important both for optimally selecting Ariel’s observational sample and for correctly interpreting the data that the mission will provide. In this challenge, INAF plays a leading role thanks to its uniquely interdisciplinary mix of skills, which has made possible such a broad spectrum analysis of the complex link between star and planetary formation ”, concludes Turrini.

Featured image: The figure shows the relationship predicted by theoretical models between the abundances of carbon and nitrogen (C / N), nitrogen and oxygen (N / O) and sulfur and nitrogen (S / N) for gas-like planets. In these models, the planets undergo an interaction-induced migration with the protoplanetary disk until they become “hot Jupiters” (gas giants in very narrow orbits). The horizontal dashed lines show the abundances of the central star. The various curves in the graphs instead show the trend of abundances both in the case in which the planet increases during the migration only gas and in the case in which it increases both gas and solids. The panel below compares the total mass increased by the planet and that due only to the planetesimals. These graphs therefore show how the determination of the relationship between the chemical abundances of certain elements, possible with future Ariel observations, can help to study the formation and migration process of planets. Credits: D. Turrini et al., Experimental Astronomy, 2021

To know more:

  • Read on Experimental Astronomy the article ” Exploring the link between star and planet formation with Ariel “, by Diego Turrini, Claudio Codella, Camilla Danielski, Davide Fedele, Sergio Fonte, Antonio Garufi, Mario Giuseppe Guarcello, Ravit Helled, Masahiro Ikoma, Mihkel Kama, Tadahiro Kimura, JM Diederik Kruijssen, Jesus Maldonado, Yamila Miguel, Sergio Molinari, Athanasia Nikolaou, Fabrizio Oliva, Olja Panic, Marco Pignatari, Linda Podio, Hans Rickman, Eugenio Schisano, Sho Shibata, Allona Vazan and Paulina Wolkenberg

Provided by INAF

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