An ongoing hunt for exoplanets has produced the first-ever detailed images of
stellar discs that are similar in size to our solar system.
The images -- photographed by the Sabaru Telescope in Hawaii --
have provided huge insight into the study of planet and solar
system formation by detailing unique features, including a lopsided
gap in one of the stellar discs which could indicate that matter
has broken off to form a giant planet.
"The most likely explanation for [the] disc gap, and in
particular its asymmetry, is that one or more planets, freshly born
from the disc material, have swept up the gas and dust along their
orbits," Christian Thalmann, who works at the Max Planck Institute
for Astronomy and led the discovery.
Stellar discs are rings of dust and gas that have been pulled in
by the gravitational pull of a young star and begin to orbit it. The stray matter is
eventually flattened out and formed into a disc by the force of the
star's pull. Concentrations of matter start to form on parts of the
disc, and as more and more matter is accumulated these dense spots
begin to develop their own centre of gravity and soon gain enough
strength to break off and become a planet. By-products of this
process -- such as gaps in the discs -- have never been captured in
such detail before and have mainly been studied through theoretical
modeling. These new images therefore provide a wealth of fresh
The stellar disc in question circles the LkCa 15 star in the Taurus
constellation, 450 light-years from Earth. It is just a few million
years old and is the perfect study subject. Images using the HiCIAO
high-contrast camera revealed light glancing off the disc's
surface, perfectly illuminating the gap and its unusual
asymmetrical shape for the first time.
It was possible to gather detailed imagery by blocking out most
of the star's light, which usually causes intense glare and makes
detecting shapes impossible. The disc appears as white light, while
the star is blacked out (depicted above). The gap is so big, it can
accommodate the orbits of all the planets in our solar system.
Another star, the AB Aur in the Auriga
constellation, is just one million years old and displayed nests of
tilted rings that do not sit symmetrically around the star,
indicating there is at least one giant planet not yet detected in
The new images were photographed as part of the SEEDS project --
Strategic Explorations of Exoplanets and Discs with Subaru. This
five-year project aims to gather as much information as possible
about exoplanets and their formation.
"We haven't detected the planets themselves yet," said Christian
Thalmann."But that may change soon."
The research was reported in Astrophysical