* Astronomy

Blobrana · L

RE: Gould Belt

Blobrana · L

Hints are emerging that around 30 million years ago, a giant clump of dark matter struck our part of the Milky Way, creating a rippling disc of star formation that eventually produced Orion's belt, the bright ruby jewel of Antares in Scorpius, and many more of the sky's most notable stars. If the scenario is correct, it could guide us in the search for a solution to one of the abiding mysteries of physics: what exactly is dark matter made of?
In the middle of the 19th century, the English astronomer John Herschel noticed that we are surrounded by a ring of bright stars. But it was Boston-born Benjamin Gould who brought this to wider attention in 1874. Gould's belt, as it is now known, supplies bright stars for many famous constellations including Orion, Scorpius and Crux, the Southern Cross, which appears on the official flags of five countries and several territories. Perseus and Canis Major in the north, along with Vela and Centaurus in the south, also contain stars in Gould's belt.

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Blobrana · L

When it comes to explaining what force could have permanently bent a ring in our Milky Way Galaxy within the last 60 million years. The real explanation may be the power of an invisible wrecking ball made of dark matter - a cloud of the enigmatic physics particles born in the fiery aftermath of the Big Bang and weighing as much as 10 million suns.
Left behind by this "Dark Matter Clump" cataclysm was a tilted swirl of newborn stars circling within the galaxy called the "Gould Belt," which incidentally may have sent comets hurtling towards Earth, suggests astrophysicist Kenji Bekki of Australia's University of New South Wales.
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Blobrana · L

Title: Dark impact and galactic star formation: Origin of the Gould belt
Authors: Kenji Bekki

The Milky Way has a giant stellar structure in the solar neighbourhood, which has a size of ~ 1 kpc, a mass of ~ 10^6 solar masses, and a ring-like distribution of young stars. Fundamental physical properties of this local enigmatic structure, known as the Gould belt (GB), have not been reproduced by previously proposed models. We first show that the local enigmatic structure can be formed about 30 Myr ago as a result of a high-speed, oblique collision between a gas cloud with a mass of ~ 10^6 solar masses and a dark matter clump with a mass of ~ 10^7 solar masses based on numerical simulations of the collision. We find that strong dynamical impact of the clump transforms the flattened cloud into a ring-like stellar structure after induced star formation within the cloud. Our simulations furthermore demonstrate that the stellar structure is moderately elongated and significantly inclined with respect to the disk of the Milky Way owing to the strong tidal torque by the colliding clump. We thus suggest that the GB is one of stellar substructures formed from collisions between gas clouds and dark matter clumps predicted in the hierarchical clustering scenario of galaxy formation. We also suggest that collisions of dark matter clumps with their host galaxies can significantly change star formation histories for some of their gas clouds thus influence galactic global star formation histories to some extent.

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