Science blog
Orbital mechanics affect methane levels
Antarctic lake keeps its secrets for now
How snakes lost their legs
Researchers ponder cancer origins
Forming social networks a no-brainer
'Niceness' partly genetic, say scientists
Omega-3 may keep blindness at bay
Coral shines light on rainfall records
Old bone proves Lucy was no swinger
Scientists unlock cosmic ice riddle
Study links pesticides to Parkinson's
Digital world growing faster every year
Energy drinks put kids at risk: report
Robotics speed up cancer drug development
Zinc cuts short the common cold
Counting kicks in at 18 months
NASA spacecraft unravels comet mystery
Astronomers dig up cannibalised galaxy
Study links extreme weather to climate change
Turkey quake gives warning clues
US scientists build first 'antilaser'
Website meltdown leaves scientists fuming
Earth 'unrecognisable' by 2050: experts
Canola fungus genome unravelled
Astronomers dig up cannibalised galaxy
Astronomers have uncovered the shredded remains of a dwarf galaxy buried deep inside the stellar disk of our own galaxy the Milky Way.

The discovery will help scientists understand how galaxies consume smaller satellite galaxies, also known as galactic cannibalism.

The findings reported in the Astrophysical Journal, were made by the RAVE (RAdial Velocity Experiment) collaboration, an international team of scientists led by Professor Fred Watson from the Australian Astronomical Observatory.

Watson says models of galactic evolution predict big galaxies should be surrounded by a lot of smaller dwarf galaxies.

"But we don't see as many of these small galaxies as we expect. One theory is they've been cannibalised by the bigger galaxies."
Stellar streams

According to Watson the stars of the dwarf galaxy are stretched out in a long trail as they orbit a larger galaxy. They remain in this formation, even after they have been swallowed up.

"It's this stream of stars moving differently compared to stars around them which signals their inter-galactic origins," he says.

RAVE astronomer Dr Mary Williams from the Astrophysical Institute in Potsdam, Germany, used the UK Schmidt Telescope at Siding Spring in New South Wales to identify 15 stars moving in a direction different to the group of 12,000 surrounding it.

Watson says, while more than a dozen star streams have been detected so far, this one is rare because it's so close.

"Being no more than 10 kiloparsecs (32,620 light years) from our solar system, places it within our Sun's neighbourhood," he says.

"These stars were discovered mostly in the disc of the galaxy rather than the galactic halo, a spherical swarm of stars surrounding the galaxy where we thought these sorts of stars should have been."
All in the motion

Watson says there was nothing unusual about these individual stars to make them stand out other than their common motion, moving at about 15,000 kilometres per hour relative to other stars in the galaxy.

"The stars are in the direction of the constellation Aquarius, so we called them the Aquarius Stream," he says.

"Their chemical composition indicates they're about ten billion years old, that's a sizeable fraction of the age of the universe so this galaxy had a independent existence for most of its life."

Watson says extrapolating the observations backwards allowed the team to determine the galactic collision generating this star stream was well underway 700 million years ago.

"It's only in the last decade that we've realised these star streams are caused by galactic collisions in the Milky Way.

"It's a science that's just coming of age."

Brain efficiency comes from parents
Backward bending light key to stealth
Signs of 'alien life' found in meteorites
Accurate blood test for Down's
Disaster volunteers at risk: study
Elephants smart as chimps, dolphins
Gadgets ruining people's sleep
Why skin doesn't dissolve in the bath
Astronomers find old heads in a young crowd
Paper leads to perfect beer head
Researchers locate brain's loudness map
Jamming may leave GPS in the wilderness
Pain washes guilt away
Quake could alter Tokyo risk: experts
Japan meltdown not like Chernobyl: expert
Dreamtime astronomers understood meteors
CERN restarts search for cosmic origins
Nuclear Contamination: What to Do
Bet-hedging 'key to natural selection'
Humans age same as other primates
US overdue, under-prepared for huge quake
Sperm's egg-seeking secrets revealed
Lasers to nudge space junk out harm's way
Researchers uncover gastro's sugary secret
Kepler probes inside swollen red giant
Randomness could 'improve democracy'
Moonageddon: Apocalypse not
Museum unveils Columbian mammoth
Ink-jet inspire scientists to make skin
Seaweed offers clues against malaria
Christchurch quakes may be connected
Solar storms pose risk to technology
Study finds fences thwart cane toad
Mobile phone alters brain activity
Sticky dots approved for clinical trial
Humans stink worse than other animals
Putting the bounce in carbon balls
Sulphur secrets uncovered
Cool laser makes atoms march in time
Hot flashes may be a sign of good heart
Scientists see the birth of a new planet
X-ray expectations change search methods
Eucalypt-harming fungus here to stay
Life elements came from outer space
Cricket wimps use perfume to find mates
Orphan planets could support life
Speech lights up visual cortex in blind
How the Sun loses its spots
Cancer resistance mechanism found
Fungus turns Amazonian ants into zombies
Tiny grains record solar system's infancy
Antarctic ice forming beneath glaciers
Visit Statistics