Why the stuff between the stars is like a glass of beer

By Nola Wilkinson  

Ever wondered what there is between the stars? Dr Naomi McClure-Griffiths not only wonders about it, she’s on a mission to find out.

Naomi is fascinated with the life of stars, the behaviour of interstellar gas, and how gas and stars interact.  “As an astronomer, I’d like to understand how the galaxy formed and how it’s living its life,” she says.

Naomi has conducted a massive survey of all the hydrogen gas in and around in the Milky Way. In doing so, she has shown that the stuff between the stars is actually foamy.

“The galaxy is much more frothy and bubbly than we ever thought. It looks like the head on a glass of beer.”

Very large stars, 8-20 times the size of our sun, experience dramatic supernova explosions that push gas out of the galaxy via solar winds travelling at up to 1000 kilometres a second.

It is these solar winds that blow bubbles in the gas between the stars, creating a frothy, foamy appearance.

Watch this video to find out more about Naomi and her amazing work:

Naomi’s team undertook the Galactic All Sky Survey using our Parkes telescope and is planning future work using our ASKAP radio telescope.


Geysers from the Galaxy’s heart

They’re big, powerful and fast. Top to bottom, they measure about half the Galaxy’s diameter. They contain as much energy as a million exploding stars. And they are roaring along at 1000 kilometres a second (yes, a second).

Revealed by our Parkes radio telescope (aka The Dish): they are giant geysers of charged particles shooting out from the centre of our Galaxy.

The finding is reported in today’s issue of Nature.

The “geysers” (in blue) shooting out of the Milky Way. (Optical image – A. Mellinger, U.Central Michigan; radio image – E. Carretti, CSIRO; radio data – S-PASS team; composition – E. Bresser, CSIRO)

The “geysers” (in blue) shooting out of the Milky Way.
Optical image – A. Mellinger, Central Michigan Uni.; radio image – E. Carretti, CSIRO; radio data – S-PASS team; composition – E. Bressert, CSIRO.

“These outflows contain an extraordinary amount of energy — about a million times the energy of an exploding star,” said the research team’s leader, CSIRO’s Dr Ettore Carretti.

But the outflows pose no danger to Earth or the Solar System.

The speed of the outflow is supersonic, about 1000 kilometres a second. “That’s fast, even for astronomers,” Dr Carretti said.

“They are not coming in our direction, but go up and down from the Galactic Plane. We are 30,000 light-years away from the Galactic Centre, in the Plane. They are no danger to us.”

From top to bottom the outflows extend 50,000 light-years [five hundred thousand million million kilometres] out of the Galactic Plane.

That’s equal to half the diameter of our Galaxy (which is 100,000 light-years — a million million million kilometres — across).

Seen from Earth, the outflows stretch about two-thirds across the sky from horizon to horizon.

So how could we have missed them before?

A couple of reasons. The particles are glowing with radio waves, rather than visible light, so seeing the geysers depends on having a telescope tuned to the right frequency (which happens to be 2.3 GHz). And the Galactic Centre is a messy, confusing place where a lot is going on.

VIDEO: Ettore Carretti talks about how the telescope makes maps of the sky.

Our Galaxy has a black hole at its centre, but it’s not that which is powering the geysers. Instead it’s star-power: “winds” from young stars, and massive stars exploding.

About half of all the star-formation that goes on in our Galaxy happens in and near the Galactic Centre. That’s a lot of stars, and a lot of energy.

VIDEO: The Parkes telescope observing as night falls and stars come out and the Milky Way appears overhead.  Credit: Alex Cherney / terrastro.com

MEDIA: Helen Sim. Mb: 0419 635 905. E: helen.sim@csiro.au


Keeping our eyes on the stars (and feet on the ground)

We’re busily preparing to show off our shiny new telescope, the Australian SKA Pathfinder, to the world. To mark the end of its construction, the telescope will be formally opened next Friday, 5 October. This time-lapse video shows the telescope’s 36 antennas standing tall in the breathtaking Western Australian landscape.

The antennas will begin making detailed pictures of distant galaxies in 2013. ASKAP has been designed to be able to survey the whole sky extremely quickly, providing the opportunity for astronomy projects never done before. Check out the ASKAP webcam or homepage for more information.

Next Friday also marks the official opening of the Murchison Radio-astronomy Observatory (MRO), where ASKAP is located.

CSIRO acknowledges the Wajarri Yamatji people as the traditional owners of the MRO site.


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