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Major space conundrum solved by computer simulation

13 February 2018

A hole at the heart of a stunning rose-like interstellar cloud has puzzled astronomers for decades - but new UK research offers an explanation for the discrepancy between the size and age of the Rosette Nebula’s central cavity and that of its central stars.

The Rosette Nebula is located in our own galaxy, the Milky Way, roughly 5,000 light-years from Earth and is known for its rose-like shape and distinctive hole at its centre.

The nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases with several massive stars found in a cluster at its heart. Stellar winds and ionising radiation from these massive stars affect the shape of the giant molecular cloud. But the size and age of the cavity observed in the centre of Rosette Nebula is too small when compared to the age of its central stars.

Using computer simulations, STFC-funded astronomers at Leeds and at Keele University have now found the formation of the nebula is likely to be in a thin sheet-like molecular cloud rather than in a spherical or thick disc-like shape, as some photographs may suggest. A thin disc-like structure of the cloud focusing the stellar winds away from the cloud’s centre would account for the comparatively small size of the central cavity.

The lead author, Dr Christopher Wareing of Leeds University, said: “The massive stars that make up the Rosette Nebula’s central cluster are a few millions of years old and halfway through their lifecycle. For the length of time their stellar winds would have been flowing, you would expect a central cavity up to ten times bigger.”

It was the thin disc that reproduced the physical appearance – cavity size, shape and magnetic field alignment — of the nebula, at an age compatible with the central stars and their wind strengths.

The team has applied the model to the ongoing Gaia survey, giving them a new understanding of the roles individual stars play in the Rosette Nebula.

Dr Wareing added: “Next we’ll look at the many other similar objects in our Galaxy and see if we can figure out their shape as well.” The nine simulations required roughly half a million CPU hours — the equivalent to 57 years on a standard desktop computer.

For more information visit the Leeds University website.

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