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SPHERE reveals a fascinating zoo of discs around young stars

New images of the SPHERE instrument on ESO's Very Large Telescope are revealing the dusty discs surrounding nearby young stars in greater detail than previously achieved. They show a strange variety of shapes, sizes and structures, including the probable effects of planets that are still in the process of formation. Credit: ESO / H. Avenhaus et al./E. Collaborations of Sissa et al./DARTT-S and SHINE

The SPHERE instrument in ESO's Very Large Telescope (VLT) in Chile allows astronomers to suppress bright light from nearby stars to obtain a better view of the regions that surround them. This collection of new SPHERE images is just a sample of the wide variety of dusty discs found around young stars.

These discs are very different in size and shape: some contain bright rings, some dark and some even resemble burgers. They also differ dramatically in appearance depending on their orientation in the sky, from circular discs face to narrow discs seen almost on edge.

The main task of SPHERE is to discover and study giant exoplanets orbiting nearby stars using direct images. But the instrument is also one of the best tools available to obtain images of discs around young stars, regions where planets can be formed. Studying such discs is essential to investigate the link between the properties of the disk and the formation and presence of planets.

Many of the young stars shown here come from a new study of T Tauri stars, a class of stars that are very young (less than 10 million years old) and vary in brightness. The discs around these stars contain gas, dust and planetesimals, the building blocks of the planets and the progenitors of the planetary systems.

These images also show how our own Solar System looked in the early stages of its formation, more than four billion years ago.

Most of the images presented were obtained as part of the DARTTS-S survey (ARound T Tauri Stars discs with SPHERE). The distances of the targets oscillated between 230 and 550 light years from Earth. By way of comparison, the Milky Way is approximately 100,000 light years in diameter, so these stars are, relatively speaking, very close to Earth. But even at this distance, it is very difficult to obtain good images of the dim light reflected from the discs, as they are eclipsed by the dazzling light of their mother stars.

Another new observation of SPHERE is the discovery of a disk advantage around the star GSC 07396-00759, found by the SHINE survey (SpHere INfrared survey for Exoplanets). This red star is a member of a multiple star system also included in the DARTTS-S sample but, interestingly, this new disc seems to be more evolved than the gas-rich disc surrounding the T Tauri star in the same system, although they are The same age. This disconcerting difference in the evolutionary scales of the discs around two stars of the same age is another reason why astronomers want to discover more about discs and their characteristics.

Astronomers have used SPHERE to obtain many other impressive images, as well as for other studies that include the interaction of a planet with a disk, the orbital movements within a system and the temporal evolution of a disk.

The new results from ESFERA, together with data from other telescopes such as ALMA, are revolutionizing astronomers' understanding of the environments surrounding young stars and the complex mechanisms of planetary formation.

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