Subaru Telescope Confirms Signs of Unseen Planets in Dust Ring of HR 4796 A

Near-infrared (1.6 micron) image of the debris ring around the star HR 4796 A.

An astronomical unit (AU) is a unit of length that corresponds to the average distance between the Earth and Sun, almost 92 million miles (over 149 million km).

The ring consists of dust grains in a wide orbit (roughly twice the size of Pluto's orbit) around the central star.

Its edge is so precisely revealed that the researchers could confirm a previously suspected offset between the ring's center and the star's location.

This "wobble" in the dust's orbit is most likely caused by the unbalancing action of, so far undetected, massive planets likely to be orbiting within the ring.

Furthermore, the image of the ring appears to be smudged out at its tips and reveals the presence of finer dust extending out beyond the main body of the ring.

The SEEDS (Strategic Exploration of Exoplanets and Disks with Subaru Telescope/HiCIAO) project, a five-year international collaboration launched in 2009 and led by Motohide Tamura of NAOJ (National Astronomical Observatory of Japan) has yielded another impressive image that contributes to our understanding of the link between disks and planet formation.

Researchers used Subaru's planet-finder camera, HiCIAO (High Contrast Instrument for the Subaru Next Generation Adaptive Optics), to take a crisp high-contrast image of the dust ring around HR 4796 A, a young (8-10 million years old) nearby star, only 240 light years away from Earth.

The ring consists of dust grains in a wide orbit, roughly twice the size of Pluto's orbit, around the central star.

The resolution of the image of the inner edge of the ring is so precise that an offset between its center and the star's position can be measured.

Although data from the Hubble Space Telescope led another research group to suspect such an offset, the Subaru data not only confirm its presence but also reveal it to be larger than previously assumed.