Hassled galaxy 'thriving on chaos'

Mar 11, 2005

Powerful but unknown forces are at work in a small companion galaxy of the Milky Way, astronomers say in today's issue of the journal Science.
Something is keeping the structure and magnetic field of this galaxy–the Large Magellanic Cloud–strong and ordered, even while the Milky Way's gravity works to tear them apart.
A team led by Bryan Gaensler of the Harvard­Smithsonian for Astrophysics used the CSIRO Australia Telescope near Narrabri in NSW to study the galaxy's magnetic field.

"This is the most detailed map ever made of another galaxy's magnetism," says Gaensler.

At just 160 000 light-years away the Large Magellanic Cloud, or LMC, is the Milky Way's closest neighbour and is being clawed apart by the Milky Way's gravity. The researchers were surprised that the LMC's magnetic field is so smooth and ordered, given the internal turmoil the galaxy must experience.

"It's like having a birthday party all afternoon for a bunch of 4-year-olds, and then finding the house still neat and tidy when they leave," Gaensler says. "Some powerful forces must be at work to keep the magnetic field from being messed up."

The Milky Way and many other large spiral galaxies have well-organised, large-scale magnetic fields. It's thought that the overall rotation of these galaxies combines and smooths out the small-scale magnetic fields created by whirls and eddies of gas. The process is called a 'dynamo', and is similar to the process that produces the Earth's magnetic field.

"But if a galaxy experiences sudden bursts of star formation or supernova explosions, the energy that these processes release should completely disrupt the large-scale magnetic field," says Lister Staveley-Smith of the CSIRO Australia Telescope National Facility. "And we know the LMC has had those kind of violent events over the last several thousand million years," he says.

So what keeps the LMC's magnetic field in order? There are several possibilities, the researchers say, but the process they favour is one driven by extremely energetic particles called 'cosmic rays'. This would take effect more quickly than the conventional dynamo mechanism. It also requires vigorous star formation to operate, so "stars bursting out at random all over would strengthen the magnetic field, not mess it up," says Gaensler. "You could say this galaxy is thriving on chaos."

Source: CSIRO

Explore further: Planetary atmospheres a key to assessing possibilities for life

add to favorites email to friend print save as pdf

Related Stories

Chandra's archives come to life

Oct 22, 2014

Every year, NASA's Chandra X-ray Observatory looks at hundreds of objects throughout space to help expand our understanding of the Universe. Ultimately, these data are stored in the Chandra Data Archive, ...

The latest observations of interstellar particles

Sep 18, 2014

With all the news about Voyager 1 leaving the heliosphere and entering interstellar space you might think that the probe is the first spacecraft to detect interstellar particles. That isn't entirely true, ...

Recommended for you

Copernicus operations secured until 2021

16 minutes ago

In a landmark agreement for Europe's Copernicus programme, the European Commission and ESA have signed an Agreement of over €3 billion to manage and implement the Copernicus 'space component' between 2014 ...

Steering ESA satellites clear of space debris

23 minutes ago

Improved collision warnings for its Earth observation missions means ESA controllers can now take more efficient evasive action when satellites are threatened by space junk.

Image: Hubble views the whirling disk of NGC 4526

33 minutes ago

This neat little galaxy is known as NGC 4526. Its dark lanes of dust and bright diffuse glow make the galaxy appear to hang like a halo in the emptiness of space in this image from the NASA/ESA Hubble Space ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.