Scientists determine large magellanic cloud galaxy formed similar to Milky Way

An astronomer from the Lawrence Livermore National Laboratory, in collaboration with an international team of researchers, have discovered that a neighboring galaxy — the Large Magellanic Cloud (LMC) — appears to have formed with an old stellar halo, similar to how our very own Milky Way formed.

The oldest and most metal-poor Milky Way stars form a spherical halo where they move about like atoms in a hot gas, which in turn prompts two major formation scenarios of our galaxy: extended hierarchical accretion and rapid collapse. RR Lyrae stars, which are found both in the Milky Way and the LMC, are excellent tracers of old and metal-poor populations.

By measuring the movement of 43 RR Lyrae stars in the inner regions of the LMC, the team determined that a moving hot, metal-poor, old halo also exists in the LMC, suggesting that the Milky Way and smaller, more irregular galaxies like the LMC have similar early formation histories.

The research, titled “Kinematic Evidence for an Old Stellar Halo in the Large Magellanic Cloud,” is featured in the Sept. 12 issue of Science.

Kem Cook of Livermore’s Institute of Geophysics and Planetary Physics and part of the Massive Compact Halo Objects (MACHO) team, which previously discovered the RR Lyrae stars in the LMC, noted that they are an easily identified tracer of an old, metal-poor population. The LMC is more than 160,000 light-years away from our galaxy.

“The bottom line is that the Large Magellanic Cloud seems to have had a similar early formation history as the Milky Way,” Cook said. “It created a spherical component that is not rotationally supported, but the stars have high random velocities, like a hot gas.”

Cook, along with scientists from Universidad Pontifica Catolica in Chile, the European Southern Observatory, Columbia Astrophysics Laboratory and the Mount Stromlo Observatory at The Australian National University, observed the LMC RR Lyrae stars in January 2003 and measured the radial velocity dispersion using the European Southern Obervatories VLT.

The large-velocity dispersion of the LMC RR Lyrae stars scales to the Milky Way RR Lyrae star’s velocity dispersion and indicates that metal-poor old stars in the LMC are distributed in a halo population.

Models of halo formation by accretion indicate that these old objects formed in small satellite galaxies that were subsequently accreted (eaten up) by the galaxy. Meanwhile, models of halo formation by dissipational collapse indicate that the halo formed rapidly before the disk collapsed. The researchers applied these models to smaller galaxies and observed a halo population in the LMC by its oldest objects.

Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy’s National Nuclear Security Administration.

Media Contact

Anne Stark EurekAlert!

More Information:

http://www.berkeley.edu/

All latest news from the category: Physics and Astronomy

This area deals with the fundamental laws and building blocks of nature and how they interact, the properties and the behavior of matter, and research into space and time and their structures.

innovations-report provides in-depth reports and articles on subjects such as astrophysics, laser technologies, nuclear, quantum, particle and solid-state physics, nanotechnologies, planetary research and findings (Mars, Venus) and developments related to the Hubble Telescope.

Back to home

Comments (0)

Write a comment

Newest articles

Results for control of pollutants in water

Brazilian scientists tested a simple and sustainable method for monitoring and degrading a mixture of polycyclic aromatic hydrocarbons, compounds present in fossil fuels and industrial waste. An article published in the journal Catalysis…

A tandem approach for better solar cells

Perovskite-based solar cells were first proved in 2009 to have excellent light-absorbing properties of methylammonium lead bromide and methylammonium lead iodide, collectively referred to as lead halide perovskites or, more…

The behavior of ant queens is shaped by their social environment

Specialization of ant queens as mere egg-layers is reversible / Queen behavioral specialization is initiated and maintained by the presence of workers. The queens in colonies of social insects, such…

Partners & Sponsors