New Leeds physics research gives insight into the heart of the Rosette Nebula

Dr Christopher Wareing is the lead author of a new study that can explain the discrepancy between the size and age of the Rosette Nebula’s central cavity and that of its central stars.

A hole at the heart of a stunning rose-like interstellar cloud has puzzled astronomers for decades. But new research led by the University of Leeds and Dr Christopher Wareing, School of Physics and Astronomy, offers an explanation.

The Rosette Nebula in the Milky Way Galaxy, roughly 5,000 light-years from Earth, 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 ionised 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.

Through computer simulations, astronomers at Leeds and at Keele University have 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.

Dr Christopher Wareing explains: “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.

“We simulated the stellar wind feedback and formation of the nebula in various molecular cloud models including a clumpy sphere, a thick filamentary disc and a thin disc, all created from the same low density initial atomic cloud.

“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."

Simulation - cloud and disk, Chris Wareing

A projection of the simulated molecular cloud and nebula along a specific line of sight (and) A slice through the simulation of the Rosette Nebula. Credit: C. J. Wareing et al.

Dr Wareing added: “To have a model that so accurately reproduces the physical appearance in line with the observational data, without setting out to do this, is rather extraordinary.

To have a model that so accurately reproduces the physical appearance in line with the observational data, without setting out to do this, is rather extraordinary.

“We were also fortunate to be able to apply data to our models from the ongoing Gaia survey, as a number of the bright stars in the Rosette Nebula are part of the survey. Applying this data to our models gave us new understanding of the roles individual stars play in the Rosette Nebula. 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 simulations, published today in the Monthly Notices of the Royal Astronomical Society, were run using the Advanced Research Computing centre at Leeds. The nine simulations required roughly half a million CPU hours — the equivalent to 57 years on a standard desktop computer.

Martin Callaghan, a member of the Advanced Research Computing team, said: “The fact that the Rosette Nebula simulations would have taken more than five decades to complete on a standard desktop computer is one of the key reasons we provide powerful supercomputing research tools. These tools enabled the simulations of the Rosette Nebula to be done in a matter of a few weeks.”

About Dr Christopher Wareing

Dr Wareing is a computational fluid dynamicist, with expertise in hydrodynamic and magneto-hydrodynamic numerical modelling through finite difference and spectral methods. He is currently working on 3D MHD astrophysical simulations of feedback in star-forming molecular clouds with Dr Julian Pittard and Professor Sam Falle at the University of Leeds, as well as continuing his work in engineering on CO2 pipelines in carbon capture and storage scenarios and now applying this to Cryogenic Machining and Rapid Expansion of Supercritical Solutions.

Dr Wareing is also a specialist in parallel computing and modelling non-linear differential equations, teaching postgraduate introduction to parallel programming courses at the University of Leeds. Previously, he has applied his expertise to late-stellar evolution objects, particularly AGB stars, planetary nebulae and neutron stars.

Further information

To learn more about Dr Wareing’s work, view his research profile.

Image credit: Rosette Nebula image is based on data obtained as part of the INT Photometric H-Alpha Survey of the Northern Galactic Plane, prepared by Nick Wright, Keele University, on behalf of the IPHAS Collaboration.

The research paper, A new mechanical stellar wind feedback model for the Rosette Nebula is published in the Monthly Notices of the Royal Astronomical Society 13 February 2018 .

For additional information please contact Anna Harrison, Press Officer at the University of Leeds.

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