Spitzer spots stardust shepherd

via Astronomy Now.

The infrared space telescope Spitzer has made observations of a star in the constellation Perseus whose light appears to be being occasionally blocked by features in the swirling dust around it.

The dust is believed to form at least two rings around the star, and something is inside the rings, stirring the inner one up in a way analogous to the satellites of Saturn shepherding ring material, as seen by Cassini in the equinox mission pictures.

The data from the star LRLL 31 could be evidence of something known as a transitional disc – a time when a planet has formed out of some disc material and sweeps out a gap where its orbit lies. Over time the gap is filled again from debris from asteroid collisions. The companion body in the transitional disc then sweeps up material, causing some of it to rise up. This heightened material is seen as hotter, shining at lower wavelengths and brighter than normal. Such changes were observed on timescales of a week – a few weeks.

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