Our galaxy is a giant ‘smoothie’ of blended stars and gas but a new study tells us where the components came from
In its early days, the Milky Way was like a giant smoothie, as if galaxies consisting of billions of stars, and an enormous amount of gas had been thrown together into a gigantic blender. But a new study picks apart this mixture by analysing individual stars to identify which originated inside the galaxy and which began life outside.
Detailed cross-section of another galaxy reveals surprising similarities to our home
The first detailed cross-section of a galaxy broadly similar to the Milky Way, published today, reveals that our galaxy evolved gradually, instead of being the result of a violent mash-up. The finding throws the origin story of our home into doubt.
The galaxy, dubbed UGC 10738, turns out to have distinct ‘thick’ and ‘thin’ discs similar to those of the Milky Way. This suggests, contrary to previous theories, that such structures are not the result of a rare long-ago collision with a smaller galaxy. They appear to be the product of more peaceful change.
And that is a game-changer. It means that our spiral galaxy home isn’t the product of a freak accident. Instead, it is typical.
Researchers find evidence of a cataclysmic flare that punched so far out of the Galaxy its impact was felt 200,000 light years away.
titanic, expanding beam of energy sprang from close to the supermassive black
hole in the centre of the Milky Way just 3.5 million years ago, sending a
cone-shaped burst of radiation through both poles of the Galaxy and out into
the finding arising from research conducted by a team of scientists led by
Professor Joss Bland-Hawthorn from Australia’s ARC Centre of Excellence for All
Sky Astrophysics in 3 Dimensions (ASTRO 3D) and soon to be published in The
On a series of calm, cool mornings in April 2017, 70 French scientists (from the French space science agency CNES, CNRS IRAP, and the Université Paul Sabatier de Toulouse) launched three enormous balloons into the sky above the heart of Australia.
CNES was using the Alice Springs Balloon Launching Centre (ASBLS) to send three precision scientific instruments up to altitudes of 30–40 kilometres to make observations that are impossible from the ground.
Scientists are using the unique advantages of Australia’s Red Centre to conduct high-altitude balloon flights for astronomical research. The clear air and low population of central Australia make it the ideal location for balloon-based research.
If the Milky Way did grow by swallowing up smaller galaxies, then another team suspects it knows where in the Milky Way some of those alien stars are hiding.
Duncan Forbes of Swinburne University of Technology and his Canadian colleague Terry Bridges are using Hubble Space Telescope data to identify clusters of alien stars, using the fact that their age and chemical composition differs from their neighbours.
But already, another Australian-led innovation in astronomical instrumentation is providing researchers with the critical information they need to understand the motions of stars within different parts of our galaxy, such as its main body, the bulging core, and the extended halo that surrounds it. Researchers are also searching for evidence of galactic cannibalism—swarms of stars that could be remnants of dwarf galaxies consumed by the Milky Way.
The innovation, called the 6dF instrument, is being used by a multinational consortium, the RAdial Velocity Experiment (RAVE), to measure the radial velocities of more than half a million stars. It is mounted on the Australian National University’s UK Schmidt Telescope at Siding Spring in New South Wales. Radial velocity is movement toward or away from the observer along the light of sight, as distinct from motion across the line of sight. The survey, which began in 2003, will be completed in 2011. Continue reading Profiling and fingerprinting the stars→
Ken Freeman is hunting for fossils. But he’s not looking for old bones—he’s exploring the very origin and history of our Milky Way galaxy.
Conventional theory says that our galaxy grew big by engulfing smaller ones. If this is correct, stars from the original galaxies should be still identifiable within the main mass of stars via several tell-tale signs, from unusual velocities to spectral types. These stellar fossils would point to the galaxy’s birth and growth. Continue reading Galactic archaeology— digging into the Milky Way’s past→
Using the Gemini South telescope in Chile, a team of astronomers led by Joss Bland-Hawthorn of the University of Sydney revealed the faint, outer regions of the galaxy called NGC 300, showing that the galaxy is at least twice the size as thought previously. The findings suggest that our own Milky Way galaxy could also be bigger than the textbooks say.