Although thousands of exoplanets are known, very little is known about their formation.
It is commonly accepted that planets form in the first millions of years of the life of planetary systems within large protoplanetary disks by the accumulation of gas and dust.
The star AB Aurigae, 520 light years away, is one of the very young systems thought to be in the early stages of planetary formation.
The ALMA radio interferometer had already been able to identify two large gas spirals in the inner zone of the system at less than 100 astronomical units.
According to the models, a protoplanet can create a gas disturbance that manifests itself in the form of spirals. Such a disturbance is similar to the wave propagating in the wake of a ship moving through the water.
The observations obtained with SPHERE at the Very Large Telescope (ESO), at the end of 2019 and beginning of 2020, not only confirmed the presence of these spirals, by observing the scattering of stellar light by the dust contained in these spirals, but also identified a structure that is similar to the torsion expected from the spiral when it is generated by a protoplanet.
In reality this torsion corresponds to the connection between two spirals: one going towards the inside of the planet’s orbit and the other towards the outside. These spirals allow the planet to accumulate matter and grow.
Although the planet at the origin of this spiral is not visible, it is the first time that such a structure can be shown, relatively well explained by the models of planetary formation as shown in the figure.
The twist is located at a distance of 30 Astronomical Units, which is about the distance of Neptune in the Solar System. However, it remains difficult to determine the mass of the object causing the twist and spirals due to the strong absorption by the surrounding gas and dust.
This new result reinforces the interest in observing very young systems, exploiting the synergy between SPHERE and ALMA.
Scientific team
The team that obtained this data is composed of A. Boccaletti (LESIA, Observatoire de Paris - PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, CNRS, France), E. Di Folco (Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS, France [Bordeaux]), E. Pantin (Laboratoire CEA, IRFU/DAp, AIM, Université Paris-Saclay, Université Paris-Diderot, Sorbonne Paris Cité, CNRS, France), A. Dutrey (Bordeaux), S. Guilloteau (Bordeaux), Y. W. Tang (Academia Sinica, Institute of Astronomy and Astrophysics, Taipei, Taiwan), V. Piétu (IRAM, Domaine Universitaire, France), E. Habart (Institute of Space Astrophysics, CNRS UMR 8617, Université Paris-Sud 11, France), J. Milli (CNRS, IPAG, Univ. Grenoble Alpes, France), T. L. Beck (Space Telescope Science Institute, Baltimore, MD, USA), and A.- L. Maire (STAR Institute, University of Liège, Belgium).
Translated with www.DeepL.com/Translator
Last update on 21 December 2021