Tuesday, June 21, 2016

Boulevard of Broken Rings

Credit: ESO/Perrot

This Picture of the Week illustrates the remarkable capabilities of 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 broken rings of dust around a nearby star. These concentric rings are located in the inner region of the debris disc surrounding a young star named HD 141569A, which sits some 370 light-years away from us.

In this image we see what is known as a transition disc, a short-lived 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 any remaining — and predominantly dusty — debris.

What we see here are structures formed of dust, revealed for the first time in near-infrared light by SPHERE — at a high enough resolution to capture remarkable detail! The area shown in this image has a diameter of just 200 times the Earth–Sun distance.

Several features are visible, including a bright, prominent ring with well-defined edges — so asymmetric that it appears as a half-ring — multiple clumps, several concentric ringlets, and a pattern akin to a spiral arm. It is significant that these structures are asymmetric; this may reflect an uneven, or clumpy, distribution of dust in the disc, 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 no planets of sufficient size to do this have been found in this system.

  • Research paper — C. Perrot et al., Discovery of concentric broken rings at sub-arcsec separations in the HD 141569A gas-rich, debris disk with VLT/SPHERE.
Source: ESO/images