Protoplanetary Disks

Protoplanetary discs observed with SPHEREPlanets form from vast disks of gas and dust, known as protoplanetary disks, encircling newborn stars. These disks can extend for billions of kilometers. Over time, the particles in protoplanetary disks collide, combine, and accrete into planet-sized bodies.

Improved observations of the details of the evolution of these planet-forming discs are now being made using ESO’s SPHERE instrument mounted on the Very Large Telescoped, improving our understanding of the enigmatic evolution of fledgling planetary systems. The central parts of the images appear dark because SPHERE blocks out the light from the brilliant central stars to reveal the much fainter structures surrounding them. Bands appear as the forming planets begin to sweep their orbits clean.

Image Credits: ESO

Making Planets?

Boulevard of Broken Rings

This picture was taken using SPHERE (the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument), a planet-hunting instrument mounted on ESO’s Very Large Telescope (VLT) in Chile. It shows a series of disrupted, concentric rings in the inner region of the debris disc surrounding a young star named HD 141569A about 370 light-years away. The image shows what is known as a transition disc, the brief stage between the protoplanetary phase, when planets have not yet formed, and a later time when planets have coalesced, leaving the disc populated only by dusty debris.

The area shown in this image has a diameter of just 200 times the Earth-to-Sun distance. Several features are visible because of the excellent detail from the SPHRE data, including a bright, prominent ring with well-defined edges which is so asymmetric that it appears as a half-ring. We can also see multiple clumps, several concentric ringlets, and a pattern that looks like a spiral arm. These structures are asymmetric, something for which astronomers do not currently have a firm explanation. It is possible that this phenomenon is caused by the presence of planets, but so far planets large enough to do this haven’t been found in the system.

Image Credit: ESO

The Fornax Cluster

FornaxClusterNamed for the southern constellation in whose part of the sky most of its galaxies can be found, the Fornax Cluster is one of the closest clusters of galaxies. At an average of 62 million light-years away, it is almost 20 times more distant than the nearby Andromeda Galaxy. Almost every yellow blob in this two-degree-wide image is an elliptical galaxy in the cluster. The barred spiral galaxy NGC 1365 that stands out in the lower right is a member of the cluster.

Image Credit: ESO