Galaxies: Some assembly required

Oct 23, 2012

New research using the world's largest telescope at the Keck Observatory in Hawaii has revealed two distinct populations of star clusters surrounding galaxies that have radically different chemical composition.

An international team, led by Swinburne astronomers Christopher Usher and Professor Duncan Forbes, has measured the chemical composition of more than 900 star clusters in a dozen galaxies.

"This is ten times the number of star clusters previously examined, allowing us to confirm the existence of two chemically-distinct star clusters," Mr Usher said.

The star clusters were selected from images of distant galaxies taken with the .

Roughly half of them were found to contain ten times more heavy elements, such as Iron and Calcium, compared to the other star clusters.

The astronomers assert that this difference in chemistry indicates that the star clusters, and the galaxy that they orbit around, were formed in two or more distinct episodes.

"It seems that galaxies were assembled in at least two different stages," Professor Forbes said.

"Unfortunately, galaxies don't come with assembly instructions.

"Reproducing our observational results will be a challenge for theorists that seek to model the using computer simulations."

Further observations are required to determine when the star clusters were formed and how they came to have such different chemical compositions. This will be the focus of future work for the Swinburne researchers.

The research team included Jean Brodie (University of California Santa Cruz), Caroline Foster (), Lee Spitler (Macquarie University), Jacob Arnold (UC Santa Cruz), Aaron Romanowsky (San Jose State University), Jay Strader (Michigan State University), and Vincenzo Pota (Swinburne University).

The research paper The SLUGGS survey: calcium triplet-based spectroscopic metallacities for over 900 globular clusters has been published in the 21 October Monthly Notices journal of the Royal Astronomical Society.

Explore further: Eclipsing binary stars discovered by high school students

Related Stories

Alien invaders pack the Milky Way

Feb 23, 2010

(PhysOrg.com) -- Around a quarter of the globular star clusters in our Milky Way are invaders from other galaxies, new research from Swinburne University of Technology (Australia) shows.

Survey Reveals Building Block Process For Biggest Galaxies

Apr 12, 2006

A new study of the universe's most massive galaxy clusters shows how mergers play a critical role in their evolution. Astronomers used the twin Gemini Observatory instruments in Hawaii and Chile, and the Hubble Space Telescope ...

Antennae Galaxies

May 19, 2008

This image of the Antennae galaxies is the sharpest yet of this merging pair of galaxies. During the course of the collision, billions of stars will be formed. The brightest and most compact of these star ...

Colliding galaxies make love, not war

Oct 17, 2006

A new Hubble image of the Antennae galaxies is the sharpest yet of this merging pair of galaxies. As the two galaxies smash together, billions of stars are born, mostly in groups and clusters of stars. The ...

Hubble Sees Star Cluster 'Infant Mortality'

Jan 10, 2007

Astronomers have long known that young or "open" star clusters must eventually disrupt and dissolve into the host galaxy. They simply don't have enough gravity to hold them together, unlike their much more ...

The survivors of a 13 billion year old massacre

Feb 14, 2012

(PhysOrg.com) -- Our Milky Way galaxy is surrounded by some 200 compact groups of stars, containing up to a million stars each. At 13 billion years of age, these globular clusters are almost as old as the ...

Recommended for you

Toothpaste fluorine formed in stars

6 hours ago

The fluorine that is found in products such as toothpaste was likely formed billions of years ago in now dead stars of the same type as our sun. This has been shown by astronomers at Lund University in Sweden, ...

Swirling electrons in the whirlpool galaxy

Aug 20, 2014

The whirlpool galaxy Messier 51 (M51) is seen from a distance of approximately 30 million light years. This galaxy appears almost face-on and displays a beautiful system of spiral arms.

A spectacular landscape of star formation

Aug 20, 2014

This image, captured by the Wide Field Imager at ESO's La Silla Observatory in Chile, shows two dramatic star formation regions in the Milky Way. The first, on the left, is dominated by the star cluster NGC ...

Exoplanet measured with remarkable precision

Aug 19, 2014

Barely 30 years ago, the only planets astronomers had found were located right here in our own solar system. The Milky Way is chock-full of stars, millions of them similar to our own sun. Yet the tally ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

cantdrive85
1 / 5 (7) Oct 23, 2012
"Reproducing our observational results will be a challenge for theorists that seek to model the formation of galaxies using computer simulations."

Just one more feather in the failure cap for the "standard theory".
Torbjorn_Larsson_OM
5 / 5 (4) Oct 23, 2012
You wish. Only a total science nincompoop can happily suggest that inflationary standard cosmology is so constrained that galaxy formation will fail it, or that there are better theories out there.

In reality, galaxy formation can be modeled by the use of the standard model but the results are widely varying, and similarly all the previous contenders to cosmology are sufficiently inferior that they have been safely rejected. http://en.wikiped...Big_Bang

If you don't know anything about the science of cosmology, why do you make sweeping claims? Most of them are bound to be embarrassingly erroneous anyway, such as the one you just made.