SPHERE reveals fascinating zoo of discs around young stars

New images from 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 bizarre variety of shapes, sizes and
structures, including the likely effects of planets still
in the process of forming. Credit: ESO/H. Avenhaus et
al./E. Sissa et al./DARTT-S and SHINE collaborations

The SPHERE instrument on ESO’s Very Large Telescope (VLT) in
Chile allows astronomers to suppress the brilliant light of
nearby stars in order to obtain a better view of the regions
surrounding them. This collection of new SPHERE images is
just a sample of the wide variety of dusty discs being found
around young stars.


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

SPHERE’s primary task is to discover and study giant exoplanets
orbiting using direct imaging .
But the instrument is also one of the best tools in existence
to obtain images of the discs around —regions where planets may be forming.
Studying such discs is critical to investigating the link
between disc properties and the formation and presence of
planets.

Many of the young 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 planets and the
progenitors of planetary systems.

These images also show what our own Solar System may have
looked like 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 (Discs ARound T Tauri Stars with SPHERE) survey. The
distances of the targets ranged from 230 to 550 light-years
away from Earth. For comparison, the Milky Way is roughly 100
000 light-years across, so these stars are, relatively
speaking, very close to Earth. But even at this distance, it is
very challenging to obtain good images of the faint reflected
light from discs, since they are outshone by the dazzling light
of their parent stars.

Another new SPHERE observation is the discovery of an edge-on
disc around the star GSC 07396-00759, found by the SHINE
(SpHere INfrared survey for Exoplanets) survey. This red star
is a member of a multiple star system also included in the
DARTTS-S sample but, oddly, this new disc appears to be more
evolved than the gas-rich disc around the T Tauri star in the
same system, although they are the same age. This puzzling
difference in the evolutionary timescales of discs around two
stars of the same age is another reason why astronomers are
keen to find out more about discs and their characteristics.

Astronomers have used SPHERE to obtain many other
impressive images
, as well as for other studies including
the interaction of a planet with a disc , the orbital
motions within a system, and the time
evolution of a disc.

The new results from SPHERE, along with data from other
telescopes such as ALMA, are
revolutionising astronomers’ understanding of the environments
around young stars and the complex mechanisms of planetary
formation.

Explore further:

Sculpting solar systems: SPHERE instrument reveals
protoplanetary discs being shaped by newborn planets

More information:
Research paper (Avenhaus et al.)


Research paper (Sissa et al.)


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