(CN) – New research offers an explanation for the discrepancy between the size and age of the hole at the center of a rose-shaped interstellar cloud and its central stars.
Located in the Milky Way Galaxy about 5,000 light-years from Earth, the Rosette Nebula is composed of dust, helium, hydrogen and other ionized gases and features several massive stars at its heart. The shape of this molecular cloud is affected by stellar winds and the ionizing radiation produced by its giant stars.
But astronomers have been confused why the nebula’s heart appears to be too young and small compared with the age of its central stars. This divergence has led some researchers to wonder how the giant celestial cloud was formed.
British astronomers from the University of Leeds and Keele University have determined that the nebula likely formed in a thin sheet-like molecular cloud, rather than a thick disc-like or spherical shape as some images may indicate.
A thin disc-like composition of the cloud, focusing the stellar winds away from its center, would explain the comparatively tiny size of the central cavity, the team writes Tuesday in the journal the Monthly Notices of the Royal Astronomical Society.
“The massive stars that make up the Rosette Nebula's central cluster are a few millions of years old and halfway through their lifecycle,” said lead author Christopher Wareing, an astronomer at Leeds. “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.”
A thin disc-like structure reproduced the physical attributes – shape, magnetic field alignment and cavity size – of the nebula, at an age consistent with its central stars and their wind powers.
“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,” said Wareing. “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 a 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 team used the Advanced Research Computing center at Leeds to run their simulations, which required about half a million CPU hours – equivalent to 57 years on a regular desktop computer.
“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,” said Martin Callaghan, a member of the Advanced Research Computing team.
“These tools enabled the simulations of the Rosette Nebula to be done in a matter of a few weeks.”Follow @SeanDuffyCNS
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