A major field of research in modern astronomy concerns itself with the question just how all of these planets are forming. Our observations tell us that the planet formation process can apparently have many different outcomes. From Trappist-1 and HR8799 all the way to the Solar System. We want to understand what influences this process and what main physical mechanisms are involved. To do that we have to observe the environment that the planets are forming in.

The image below depicts the standard process of star and planet formation. We start out with an enormous cloud of mostly molecular gas. This cloud collapses under its on gravity and a proto-star is born. Since the cloud material will have some slight almost random motion the material starts to spin faster and faster as it starts to collapse and forms a thick disk of gas and dust around the young proto-star. These disks slowly dissipate over the course of the first roughly 10 million years of the life of the new stellar system (a very short time period in the life of a star that may last billions of years). It is in these disks of gas and dust that planets are born.

Due to technological progress made in astronomical instrumentation it is today possible to directly observe planet-forming disks around nearby stars. In the below image we show actual data taken in near-infrared light (light slightly redder than humans can see with just their eyes) with the European Southern Observatory's (ESO) Very Large Telescope. This is the one of the largest optical and near-infrared telescopes currently in existence with a mirror diameter of 8.2m. Due to Ireland's ESO membership, these telescopes are available to all astronomers at Irish universities.

The image shows disks around three different young stars. They look different than disks that many people may think of in our solar system like the rings of Saturn, which are razor thin. These disks instead are actually having a shape almost like a bowl-plate and are very thick on their outer edges. Quite by chance the disks have different inclinations relative to us. That means that the first one we see from a top down perspective, the last one we see from the side and the middle one from somewhere in between. The light that you see is actually the light from the central star in each of these systems which gets scattered (think of it as being reflected) by tiny dust particles (think grains of sand) at the "surface" layer of the disk. This leads to the peculiar appearance of these disks that are reminiscent of an Oreo cookie. The lane between the two bright layers does not receive any light from the star and so appears dark.

As it turns out disks do not always look as tranquil and relatively smooth as the ones in the image above. Many of them show intricate structures such as rings, spiral arms or even shadows (some can be seen in the image below, click this link to see a large gallery). This diversity in the appearance of planet forming disks was only discovered in recent years and is believed to be linked to the diversity of fully formed exoplanet systems that we have discovered.

To understand how disks and their appearance evolved over time the DESTINYS program was started. DESTINYS stands for Disk Evolution Study Through Imaging of Nearby Young Stars. It is a dedicated ESO large program that uses the SPHERE extreme adaptive optics system at the ESO VLT to get images of many planet forming disks which are all at different stages of their evolution. From this data we can learn how older disks compare to younger disks, or how disks in different regions and environments compare to each other. The program is lead by Christian Ginski at the University of Galway.