VLT Finds Protoplanetary Disks around 86 Young Stars

New observations of 86 planet-forming disks provide astronomers with a wealth of data and unique insights into how planets arise in different regions of the Milky Way.

Planet-forming disks around young stars and their location within the gas-rich cloud of Taurus, roughly 600 light-years from Earth. In total, the scientists observed 43 stars in the Taurus region, all of which are pictured here (though planet-forming disks were only detected in 39 of these targets). Image credit: ESO / Garufi et al. / IRAS.

To date more than 5,000 exoplanets have been discovered, often within planetary systems markedly different from our own Solar System.

To understand where and how this diversity arises, astronomers must observe the dust- and gas-rich disks that envelop young stars — the very cradles of planet formation. These are best found in huge gas clouds where the stars themselves are forming.

Much like mature planetary systems, the new images from ESO’s Very Large Telescope (VLT) showcase the extraordinary diversity of planet-forming disks.

“Some of these disks show huge spiral arms, presumably driven by the intricate ballet of orbiting planets,” said University of Galway astronomer Christian Ginski.

“Others show rings and large cavities carved out by forming planets, while yet others seem smooth and almost dormant among all this bustle of activity,” added Arcetri Astrophysical Observatory astronomer Antonio Garufi.

The authors studied a total of 86 stars across three different star-forming regions of our Galaxy: Taurus and Chamaeleon I, both around 600 light-years from Earth, and Orion, a gas-rich cloud about 1,600 light-years from us that is known to be the birthplace of several stars more massive than the Sun.

In the Orion cloud, they found that stars in groups of two or more were less likely to have large planet-forming disks.

This is a significant result given that, unlike our Sun, most stars in our Galaxy have companions.

As well as this, the uneven appearance of the disks in this region suggests the possibility of massive planets embedded within them, which could be causing the disks to warp and become misaligned.

While planet-forming disks can extend for distances hundreds of times greater than the distance between Earth and the Sun, their location several hundreds of light-years from us makes them appear as tiny pinpricks in the night sky.

To observe the protoplanetary disks, the astronomers used VLT’s Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE).

Additional data were obtained using the VLT’s X-SHOOTER instrument, which allowed the researchers to determine how young and how massive the stars are.

The Atacama Large Millimeter/submillimeter Array (ALMA) helped them understand more about the amount of dust surrounding some of the stars.

“It is almost poetic that the processes that mark the start of the journey towards forming planets and ultimately life in our own Solar System should be so beautiful,” said Per-Gunnar Valegård, a doctoral student at the University of Amsterdam.

The findings will appear in three papers in the journal Astronomy & Astrophysics.