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Australian dish charts where stars are born

Jonathan Nally — Thu, 01 Dec 2011 08:35:48 +0000

The Large Magellanic Cloud (LMC) is the nearest sizeable galaxy to our Milky Way, and is therefore a popular target for astronomers studying the evolution of stars.

ASTRONOMERS HAVE MAPPED in detail the star-forming regions of the nearest star-forming galaxy to our own, a step toward understanding the conditions surrounding star creation.

The researchers, led by University of Illinois astronomy professor Tony Wong—and including Associate Professor Sarah Maddison and PhD student Annie Hughes, both of the Swinburne University of Technology in Melbourne, Australia—have published their findings in the December issue of the Astrophysical Journal Supplement Series.

The Large Magellanic Cloud (LMC) is a popular galaxy among astronomers both for its nearness to our Milky Way and for the spectacular view it provides, a big-picture vista impossible to capture of our own galaxy.

“If you imagine a galaxy being a disc, the LMC is tilted almost face-on so we can look down on it, which gives us a very clear view of what’s going on inside,” Wong said.

CSIRO's 22-metre-diameter Mopra radio telescope, located near Coonabarabran in NSW.

As the LMC is in the far southern sky, it is an ideal target for Australian telescopes. And indeed, the team used the CSIRO’s 22-metre-diameter radio telescope at Mopra, near Coonabarabran in north-central New South Wales.

Where are stars born?

Although astronomers have a working theory of how individual stars form, they know very little about what triggers the process or the conditions in space that are optimal for star birth.

Wong’s team focused on areas called molecular clouds, which are dense patches of gas—primarily molecular hydrogen—where stars are born. By studying these clouds and their relationship to new stars in the galaxy, the team hoped to learn more about how gas clouds turn into stars.

Using the Mopra dish, the astronomers mapped more than 100 molecular clouds in the LMC and estimated their sizes and masses, identifying regions with ample material for making stars. This seemingly simple task engendered a surprising find.

Conventional wisdom states that most of the molecular gas in a galaxy is apportioned to a few large clouds. However, Wong’s team found many more low-mass clouds than they expected—so many, in fact, that a majority of the dense gas may be sprinkled across the galaxy in these small molecular clouds, rather than clumped together in a few large blobs.

False-colour image of the Large Magellanic Cloud galaxy combining maps of neutral atomic hydrogen gas (red), hydrogen energised by nearby young stars (blue), and new data from Wong’s team which roughly show the locations of dense clouds of molecular hydrogen (green). It's thought that stars form within molecular hydrogen clouds.

Star formation widespread in the LMC galaxy

The large numbers of these relatively low-mass clouds means that star-forming conditions in the LMC may be relatively widespread and easy to achieve.

To better understand the connection between molecular clouds and star formation, the team compared their molecular cloud maps to maps of infrared radiation, which reveal where young stars are heating cosmic dust.

“It turns out that there’s actually very nice correspondence between these young massive stars and molecular clouds,” Wong said.

“We can say with great confidence that these clouds are where the stars form, but we are still trying to figure out why they have the properties they do,” he added.

Adapted from information issued by University of Illinois at Urbana-Champaign. Mopra photo courtesy CSIRO. MAGMA image of LMC courtesy Tony Wong, University of Illinois.

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Aussie astronomer wins top prize

Jonathan Nally — Fri, 04 Nov 2011 02:56:23 +0000

2011 Young Tall Poppy of the Year for NSW award recipient, Dr George Hobbs of the CSIRO, uses observations of pulsars (artist's impression) in the hunt for gravitational waves.

CSIRO ASTRONOMER Dr George Hobbs has become the 2011 Young Tall Poppy of the Year for NSW.

The award was presented at the Powerhouse Museum in Sydney on Thursday 3 November. Dr Hobbs was chosen from a field of eleven Young Tall Poppies to receive the top honour.

The Young Tall Poppy Science Awards, given each year by the Australian Institute of Policy and Science, recognise excellent early career research and passion in communication and community engagement.

Dr Hobbs, based in Sydney at CSIRO Astronomy and Space Science, works on pulsars—small stars with regular clock-like radio signals.

Dr George Hobbs

He leads a program on CSIRO’s Parkes radio telescope to search for gravitational waves, using pulsars as markers.

“Gravitational waves are ripples in spacetime,” Dr Hobbs said. “Einstein predicted them but they’ve never been observed directly.”

“Of course, we hope to be the first to do this.”

Engaging the next generation

Dr Hobbs is also a key scientist in an outreach program called PULSE@Parkes, which allows students to control the Parkes telescope over the internet and use it to observe pulsars.

CSIRO will use the experience of PULSE@Parkes to develop remote-observing education programs for the Australian SKA Pathfinder radio telescope it is now building in WA.

The Parkes radio telescope

At a recent PULSE@Parkes session, students had the thrill of seeing a pulsar turn its signal on and off while they watched: a very rare phenomenon, occurring in just a handful of the 2000-odd known pulsars.

“Then I and the other scientist stood in front of the students and offered quite different ideas about why this might be happening,” Dr Hobbs said.

“They were seeing real science in action.”

In addition to these activities, Dr Hobbs also finds time to do other ground-breaking science, including a fundamental discovery about how pulsars work.

This year he was also named by the Chinese Academy of Sciences as an International Young Scientist of China, for his collaborative work with institutions in Xi’an, Urumqi and Beijing.

And what car does 34-year-old Dr Hobbs drive? A Nissan Pulsar, of course.

Adapted from information issued by CSIRO. Images courtesy David McClenaghan (CSIRO) and NASA.

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Milky Way galaxy is a ‘snake pit’

Jonathan Nally — Wed, 05 Oct 2011 20:28:49 +0000

CSIRO's Australia Telescope Compact Array was used to make a map of galactic gas polarisation.

A PIT OF WRITHING SNAKES. That’s what the first picture of turbulent gas inside our Milky Way galaxy looks like.

Professor Bryan Gaensler of the University of Sydney, Australia, and his team used a CSIRO radio telescope in eastern Australia to make the ground-breaking image, published in the journal Nature today.

The space between the stars in our Galaxy is not empty, but is filled with thin gas that continually swirls and churns.

“This is the first time anyone has been able to make a picture of this interstellar turbulence,” said Professor Gaensler. “People have been trying to do this for 30 years.”

Turbulence makes the Universe magnetic, helps stars form, and spreads the heat from supernova explosions through the Galaxy

“We now plan to study turbulence throughout the Milky Way. Ultimately this will help us understand why some parts of the Galaxy are hotter than others, and why stars form at particular times in particular places,” Professor Gaensler said.

Spectacular image

Gaensler and his team studied a region of our Galaxy about 10,000 light-years away in the constellation Norma.

They used CSIRO’s Australia Telescope Compact Array near Narrabri, NSW, because “it is one of the world’s best telescopes for this kind of work,” as Dr Robert Braun, Chief Scientist at CSIRO Astronomy and Space Science explained.

The radio telescope was tuned to receive radio waves that come from the Milky Way. As these waves travel through the swirling interstellar gas, one of their properties—polarisation—is very slightly altered, and the radio telescope can detect this.

(Polarisationis the direction the waves “vibrate”. Light can be polarised—for instance, some sunglasses filter out light polarised in one direction while letting through other light.)

A map has been made of the gas in our Milky Way galaxy. The 'snakes' are regions of gas where the density and magnetic field are changing rapidly as a result of turbulence.

The researchers measured the polarisation changes over an area of sky and used them to make a spectacular image of overlapping entangled tendrils, resembling writhing snakes.

The “snakes” are regions of gas where the density and magnetic field are changing rapidly as a result of turbulence.

Best match

The “snakes” also show how fast the gas is churning — an important number for describing the turbulence.

Team member Blakesley Burkhart, a PhD student from the University of Wisconsin, made several computer simulations of turbulent gas moving at different speeds.

These simulations resembled the “snakes” picture, with some matching the real picture better than others.

By picking the best match, the team concluded that the speed of the swirling in the turbulent interstellar gas is around 70,000 kph—relatively slow by cosmic standards.

Adapted from information issued by CSIRO. Images courtesy B. Gaensler et al. (data: CSIRO/ATCA) and David Smyth, CSIRO.

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‘The Dish’ finds a ‘diamond planet’

Jonathan Nally — Fri, 26 Aug 2011 02:39:42 +0000

An artist's visualisation of the pulsar and its orbiting planet, which astronomers think could be made partly of diamond or a diamond-like substance. The blue squiggly line represents the beams of radio waves emanating from the pulsar. The orange bubble represents the size of the Sun, showing that the the planet's orbit has about the same radius as the Sun (about 600,000 km), yet it whizzes around in just two hours!

Planet detected orbiting a pulsar 4,000 light-years away
It’s actually the remnant core of what was once a star
Probably made of compressed carbon—diamond!

ASTRONOMERS USING ‘THE DISH’—CSIRO’s radio telescope near Parkes, NSW—believe they’ve found a small planet made of diamond, orbiting an unusual star.

The discovery was made by an international research team, led by Professor Matthew Bailes of Swinburne University of Technology in Melbourne, Australia, and is reported today in the journal Science.

“Although bizarre, this planet is evidence that we’ve got the right understanding of how these binary systems evolve,” said Dr Michael Keith of CSIRO Astronomy and Space Science, one of the research team members.

Not fitting the pattern

The researchers, from Australia, Germany, Italy, the UK and the USA, first found an unusual star called a pulsar, now named PSR J1719-1438, using the 64-m Parkes radio telescope in eastern Australia.

Pulsars are small spinning stars about 20 km in diameter—the size of a small city—that emit a beam of radio waves. As the star spins and the radio beam sweeps repeatedly over Earth, radio telescopes detect a regular pattern of radio pulses.

The researchers followed up their discovery with the Lovell radio telescope in the UK and one of the Keck telescopes in Hawaii, and noticed that the arrival times of the pulsar’s pulses were systematically altered—in a way that must be caused by the gravitational pull of a small planet orbiting the pulsar.

The CSIRO's Parkes radio telescope

Small, heavy and fast

The modulations of the radio pulses reveal several things about the planet.

First, it orbits the pulsar in just two hours and ten minutes, and the distance between the two objects is 600,000 km—a little less than the radius of our Sun.

Second, the companion must be small, less than 60,000 km (that’s about five times the Earth’s diameter). The planet is so close to the pulsar that, if it were any bigger, it would be ripped apart by the pulsar’s gravity.

But despite its small size, the planet has slightly more mass than Jupiter.

A stripped-down dwarf

“This high density of the planet provides a clue to its origin,” Professor Bailes said.

The team thinks that the ‘diamond planet’ is all that remains of a once-massive star, most of whose matter was siphoned off towards the pulsar.

But pulsar J1719-1438 and its companion are so close together that the companion can only be a very stripped-down ‘white dwarf’ star, one that has lost its outer layers and over 99.9 per cent of its original mass.

“This remnant is likely to be largely carbon and oxygen, because a star made of lighter elements like hydrogen and helium would be too big to fit the measured orbit,” said CSIRO’s Dr Keith.

The density means that this material is certain to be crystalline—that is, a large part of the star may be similar to a diamond.

The pulsar and its planet lie 4,000 light-years away in the constellation of Serpens (the Snake). The system is about an eighth of the way towards the Galactic Centre from the Earth.

Diamond planet Easy Q&A

What have they found?

They’ve spotted a system that comprises a weird kind of star, called a pulsar, and a medium-sized planet that is probably made of almost pure carbon…which is most likely in the form of diamond or a diamond-like substance.
The system is 4,000 light-years from Earth—that’s 40 thousand trillion kilometres away!
The pulsar emits radio waves in a regular pattern as it spins, like a lighthouse, which is what the CSIRO’s Parkes radio telescope picked up.
The planet itself cannot be seen as it is too small and too far away.

If they can’t see the planet, how do they know it’s really there?

Its presence is inferred by the distorting effect it has on the pulsar’s powerful radio emissions.
It whizzes around its star in just two hours (compared to one year for Earth around the Sun).
The data was analysed using an incredible supercomputer at Swinburne University in Melbourne.
The planet is about 5 times as wide as the Earth, but much, much heavier.

So why do they think it is made of diamond?

Now here’s the interesting bit, because the planet actually seems to be the dense, remnant core of a star, rather than a traditional planet.
Many stars, as they burn up their hydrogen fuel, end up having cores made of carbon.
The star changed into a planet, with only it’s core remaining.

How did it change from a star into a planet?

Because the pulsar has a huge gravitational pull and is a cosmic cannibal!
The pulsar and the other star would have been orbiting very close to each other.
The pulsar would have pulled all the outer gas layers off the other star—99.9 percent of its mass—eventually leaving it with just its carbon core.
If we could have seen it happening, it would have looked like a huge whirlpool of gas coming off the doomed star and spiralling onto the neighbouring pulsar.

What do astronomers hope to learn from these types of star systems?

For one thing, pulsars are the “end points”—the dying stages—in the lives of many kinds of big stars, so learning more about them tells us about the evolution and life cycle of those stars and the wider universe.
But pulsars also are important for understanding and testing laws of physics.
Astronomers can use them as “natural laboratories” for testing theories, such as Einstein’s theory of gravity.
That’s because you can only go so far testing some theories in the laboratory—to really put them to the test, you need to study massive objects travelling at high speed, and that’s what pulsar systems are.

Main text adapted from information issued by CSIRO. Q&A by Jonathan Nally, SpaceInfo.com.au Images courtesy Swinburne Astronomy Productions and David McClenaghan, CSIRO.

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Galaxies are running out of gas

Jonathan Nally — Tue, 23 Aug 2011 03:53:03 +0000

Compared to earlier cosmic epochs, galaxies these days are running of out of the gas raw material with which to make new stars. (Hubble Space Telescope image.)

THE UNIVERSE FORMS FEWER STARS than it used to, and a CSIRO study has now shown why—compared to the past, galaxies today have less gas from which to make stars.

Dr Robert Braun (CSIRO Astronomy and Space Science) and his colleagues used CSIRO’s Mopra radio telescope near Coonabarabran, NSW, to study far-off galaxies and compare them with nearby ones.

Light (and radio waves) from the distant galaxies takes time to travel to us, so we see the galaxies as they were between three and five billion years ago.

Galaxies at that stage of the Universe’s life appear to contain considerably more molecular hydrogen gas than comparable galaxies in today’s Universe, the research team found.

Stars form from clouds of molecular hydrogen. The less molecular hydrogen there is, the fewer stars will form.

The research team’s paper is in press in Monthly Notices of the Royal Astronomical Society.

Raw material for stars

Astronomers have known for at least 15 years that the rate of star formation peaked when the Universe was only a few billion years old and has declined steeply ever since.

“Our result helps us understand why the lights are going out,” Dr Braun said. “Star formation has used up most of the available molecular hydrogen gas.”

CSIRO's Mopra radio telescope near Coonabarabran in New South Wales.

After stars form, they shed gas during various stages of their lives, or in dramatic events such as explosions (supernovae). This returns some gas to space to contribute to further star formation.

“But most of the original gas—about 70%—remains locked up, having been turned into things such as white dwarfs, neutron stars and planets,” Dr Braun said.

“So the molecular gas is used up over time. We find that the decline in the molecular gas is similar to the pattern of decline in star formation, although during the time interval that we have studied, it is declining even more rapidly.”

Dark energy the demon

Ultimately, the real problem is the rate at which galaxies are “refuelled” from outside.

Gas falls into galaxies from the space between galaxies, the intergalactic medium. Two-thirds of the gas in the universe is still found in the intergalactic medium—the space between the galaxies—and only one third has already been consumed by previous star formation in galaxies, astronomers think.

“The drop-off in both gas availability and star formation seems to have started around the time that Dark Energy took control of the Universe,” Dr Braun said.

Up until that time, gravity dominated the Universe, so the gas was naturally pulled in to galaxies, but then the effect of Dark Energy took over and the Universe started expanding faster and faster.

This accelerating expansion has probably made it increasingly difficult for galaxies to capture the additional gas they need to fuel future generations of star formation, Dr Braun speculates.

Adapted from information issued by CSIRO; NASA, ESA, STScI/AURA.

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Dishes take shape in the desert

Jonathan Nally — Thu, 07 Jul 2011 12:00:05 +0000

The Australian Square Kilometre Array Pathfinder, or ASKAP, is under construction in the remote Western Australian desert.

THE CSIRO’S LATEST RADIO TELESCOPE—the Australian Square Kilometre Array Pathfinder, or ASKAP—is now taking shape in the remote Western Australian desert.

When completed in 2012 it will comprise 36 dishes all acting in concert to produce the same result as one big dish. Cutting-edge receiver technology invented by CSIRO scientists will give it an extremely wide field of view. This, coupled with high-speed electronics and an ultra-fast optical fibre link to a dedicated computing centre in Perth, will make ASKAP arguably the best radio telescope system in the world.

ASKAP’s first five years of observations are already booked out by teams from around the world, and the science studies it will tackle are some of the biggest around—how did the earliest stars and galaxies form; how have galaxies evolved through time; what role has magnetism played in the cosmos; and can Einstein’s theories stand ever-more stringent tests?

ASKAP Project Director, Antony Schinckel

ASKAP is also the Australian and New Zealand “pathfinder” for the ultimate prize—the Square Kilometre Array, or SKA. The SKA will be a vast collection of thousands of dishes and antennae spread across an area the size of a continent. A decision will be made next year by an international committee, as to whether the SKA will be hosted in Australia-New Zealand or southern Africa. The linked telescopes will make images ten times more detailed than those of the Hubble Space Telescope.

SpaceInfo.com.au wanted to get an update on progress with ASKAP, so we spoke to the man in charge—ASKAP Project Director Antony Schinckel, of CSIRO’s Astronomy and Space Science division—to find out how things are going in the WA desert:

Can you give us a rundown on the state of construction of ASKAP?

We’re very happy with how things are going—we’re at the point where there is substantial activity on site. Major infrastructure construction commenced in May. The first phase of that was that the company doing the work needed to put in their temporary accommodation camp, as there are no motels for hundreds of kilometres!

Between now and early December we’ll complete all of the 30 remaining antenna foundations, the access tracks to each antennae, fibre and power distribution around the site and to each antenna, and then the central building as well—all of the primary infrastructure that doesn’t include the science instruments and power systems.

It must be a difficult task, building hi-tech facilities that are essentially in the middle of nowhere?

With these remote sites there are a lot of logistics that need to be understood and got moving properly, but the contractors have a fair bit of experience with that. Most of it is normal civil engineering, although there are a few subtleties—for instance, the concrete foundations for the antennae need to be a certain minimum stiffness.

The unusual bits in a sense are the optical data fibre links between the antennae and the central site. Our raw data rate will be phenomenally high, about 74 terabits per second for the total 36 antennae. That data then goes into some special equipment (the beam former and the correlator) which ramps down the rate fairly significantly before it is sent via cable down to Perth.

ASKAP will comprise 36 hi-tech antennae

How are you going to handle the enormous amounts of data produced by the 36 ASKAP antennae?

Well, it’s going to be a really interesting challenge how we treat this. We can’t afford to archive the absolute raw data—the volume is just too high. So working out which are the critical data products to archive right up front is going to prove a real challenge. We’ve clearly got some plans on which ones are the most important, but it’ll be fascinating to see over the next few years if we end up archiving those or finding we have to modify it a little bit.

The Pawsey Centre in Perth is a key part of this in terms of the data reduction.

The actual fibre in the ground that CSIRO has put in, is through a contract with AARNet with major sub-contracts to CCTS and North Coast Holdings, out of Geraldton. The fibre has now been fully laid and tested. The fibre is all buried, which is easier long term than having it up on aerial poles. The fibre is better protected when buried. There are three booster huts along the length of the fibre.

There are two remote booster huts that are solar powered with the possibility of back-up diesel if required. And there’s one in the town of Mullewa, which is just on grid power with back-up.

As far as terrain goes, there’s a gentle slope 350km up from Geraldton to the site—we end up at an elevation of about 370 metres.

How will you supply electrical power to such a remote site?

With power, our intention long-term is to have as a renewable a power source as we possibly can. For all sorts of obvious reasons, we want to go with generating most of our power through whatever renewable resources we have. Out in that region of Western Australia in particular, solar power is extremely attractive. It’s one of the places with the highest solar insolation in the world. So solar will be a substantial part of it.

To begin with we’ll have a base power capability from diesel generators, but over a number of years we’ll be expecting to be adding or start off with some solar on top of the diesel, and then in a couple of more years we have some additional funds that will enable us to expand that significantly around 2013-14.

The CSIRO has been particularly pleased with the quality of the antennae, built by the 54th Research Institute of China Electronics Technology Group Corporation (known as CETC54).

Power storage is something of an issue. That’s partly why we’ve put the funding back a couple of years, to see what eventuates with power storage options by the time ASKAP is really up and operational. The focus now is on what we need to get it going.

You have six dishes installed and two more being installed right now. What’s the schedule for the rest of them?

It’s a fairly continuous process of installing the remaining antennae right through this year and into early 2012, at about 3 to 4 per month. A team from the Chinese manufacturer, CETC54, comes out to supervise their construction.

With the dishes, there’s one point there that we’ve been particularly thrilled with. We specified a surface accuracy of 1mm but the delivered capability substantially exceeds that—most of the antennae are coming in with an accuracy of about 0.5mm. This means in the long-term they could be used to do observations at much higher frequencies than originally planned, giving us very good long-term flexibility.

Another thing that CETC54 has achieved is that we don’t have to adjust the surfaces. They’ve come up with a manufacturing technique in China and then at installation here that means it’s literally a case of just bolting the dish panels together … there’s no fine adjustment necessary here in Australia.

Given that it is such remote site, will there be people stationed there on a regular basis?

No, not for operations. Like most telescopes these days, it can be operated by remote control from anywhere. However, with an array as big and as complex as this—36 antennae, vast data rates, these huge specialised digital systems—it really is a dramatic step forward. The telescope is about a factor of 10 more powerful than any other radio telescope in the world. So regular maintenance will be required to keep the system up and running, and there will be people going out to the site to do that.

ASKAP is being built in one of the remotest parts of the world, 350 kilometres inland from Geraldton in Western Australia.

Finally, from a personal standpoint, what’s it like to be out there in the WA desert? The conditions must be pretty challenging.

Many telescopes are built in remote sites, but mostly they’re built where there’s already some level of infrastructure. For us working out at Boolardy Station, you have to bring in absolutely everything. You know intellectually that that’s true, but nonetheless on the day when you realise you really do need that special screwdriver, you find it is 350km away! It’s one of those classics where you know philosophically how to do something, and you think you’ve got it covered…but boy, there really is no give and take on that.

Summers out there are pretty warm. We’ve managed to move schedules around to deal with that, and it’s quite manageable; it’s just a case of thinking things out sensibly. We’ve worked a lot with regional contractors in WA who are experienced at this and we’ve shifted our mindset to suit the climate.

The wildlife situation reminds us that we’re living in Australia. The numbers of kangaroos, emus, goannas and snakes, has been quite impressive. Snakes in particular are the most dangerous local wildlife, but we’ve got good procedures in place to deal with them.

Story by Jonathan Nally, SpaceInfo.com.au. Images courtesy CASS / Terrace Photographers / Paul Bourke and Jonathan Knispel (Supported by WASP (UWA), iVEC, ICRAR, and CSIRO).

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Milestone as radio dishes linked

Jonathan Nally — Thu, 07 Jul 2011 01:39:24 +0000

Antennae of CSIRO's Australian SKA Pathfinder (ASKAP) telescope in Western Australia were linked with other dishes across Australasia to provide incredible detail of a distant quasar. Photo: Terrace Photographers

THE DISCOVERY POTENTIAL of the future international Square Kilometre Array (SKA) radio telescope has been glimpsed following the commissioning of a working optical fibre link between CSIRO’s Australian SKA Pathfinder (ASKAP) telescope in Western Australia, and other radio telescopes across Australia and New Zealand.

The achievement will be announced at the 2011 International SKA Forum, taking place this week in Banff, Canada.

On 29 June, six telescopes—ASKAP, three CSIRO telescopes in New South Wales, a University of Tasmania telescope and another operated by the Auckland University of Technology—were used together to observe a radio source that may be two black holes orbiting each other.

Data from all sites were streamed in real time to Curtin University in Perth (a node of the International Centre for Radio Astronomy Research) and there processed to make an image.

This ability to successfully link antennae (dishes) over large distances will be vital for the future $2.5 billion SKA telescope, which will have several thousand antennae, up to 5,500 kilometres apart, working together as a single telescope. Linking antennae in such a manner allows astronomers to see distant galaxies in more detail.

The network of radio telescope dishes stretched across Australia and New Zealand. Image: Carl Davies, CSIRO

“We now have an SKA-scale network in Australia and New Zealand: a combination of CSIRO and NBN-supported fibre and the existing AARNET and KAREN research and education networks,” said SKA Director for Australasia, Dr Brian Boyle.

Watching as black holes feed

The radio source the astronomers targeted was PKS 0637-752, a quasar that lies more than seven and a half billion light-years away from us.

This quasar emits a spectacular radio jet with regularly spaced bright spots in it, like a string of pearls. Some astronomers have suggested that this striking pattern is created by two black holes in orbit around each other, one black hole periodically triggering the other to ‘feed’ and emit a burst of radiation.

The radio dish network was used to zoom in on quasar PKS0637-752, at the heart of which is thought to be two black holes circling each other. ATCA image: L. Godfrey (Curtin Uni.) and J. Lovell (Uni. of Tasmania). Image from telescope network: S. Tingay (Curtin Uni.) et al.

‘It’s a fascinating object, and we were able to zoom right into its core, seeing details just a few millionths of a degree in scale, equivalent to looking at a 10-cent piece from a distance of 1,000 kilometres,’ said CSIRO astronomer Dr Tasso Tzioumis.

During the experiment Dr Tzioumis and fellow CSIRO astronomer Dr Chris Phillips controlled all the telescopes over the Internet from Sydney.

Curtin University’s Professor Steven Tingay and his research team built the system used to process the telescope data. “Handling the terabytes of data that will stream from ASKAP is within reach, and we are on the path to the SKA,” he said.

“For an SKA built in Australia and New Zealand, this technology will help connect the SKA to major radio telescopes in China, Japan, India and Korea.”

AARNet, which provides the data network for Australia’s research institutions, has recently shown that it can implement data rates of up to 40 Gbps on existing fibre networks. That figure is for a single wavelength, and one fibre can support up to 80 wavelengths.

Adapated from information issued by CSIRO Astronomy and Space Science.

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Aboriginal community names CSIRO telescope

Jonathan Nally — Thu, 02 Jun 2011 22:26:56 +0000

One of the ASKAP dishes at the Murchison Radio-astronomy Observatory in Western Australia. The first six dishes (of an eventual 36) have been given indigenous names.

THE FIRST SIX ANTENNAE of CSIRO’s Australian SKA Pathfinder telescope in Western Australia have today received names in the local Wajarri language.

The names, chosen by the Wajarri people, were bestowed by representatives of seven Aboriginal families at a ceremony at the Murchison Radio-astronomy Observatory, about 315 km northeast of Geraldton.

Name plaques will be fixed to each antenna. Further naming will take place as more antennae are installed and eventually all 36 of ASKAP’s antennae will have a Wajarri name.

The antenna names are: Bilyarli (which means “galah”, and is also the name of a past Wajarri Elder, Mr Frank Ryan); Bundarra (stars); Wilara (the Moon); Jirdilungu (the Milky Way); Balayi (a lookout, as this antenna looks down westward to others); and Diggidumble (a nearby table-top hill).

CSIRO ASKAP Director, Antony ("Ant") Schinckel has been named "Minga", the Wajarri name for "ant".

“These names will be a permanent reminder that this is the land of the Wajarri people,” said the Chair of Wajarri Yamatji Native Title Group, Gavin Egan.

Roads and other significant structures will also be given Wajarri names.

One of the roads will be called Ngurlubarndi, the Wajarri name for Fred Simpson, a past Wajarri Elder and father of Wajarri Elder, Ike Simpson.

CSIRO’s ASKAP Director, Antony (“Ant”) Schinckel has also been given a Wajarri name—”Minga”, which means “ant”.

In March CSIRO awarded McConnell Dowell Constructors (Aust) Pty Ltd the contract to construct support infrastructure at the Murchison Radio-astronomy Observatory.

The work involves the construction of several kilometres of access roads and tracks, power and data distribution, a central control building, and foundation pads for the rest of the 36 antennae that will be installed on the site by early 2012.

The MRO is located in the Mid West region of Western Australia. As well as being home to ASKAP, it is also the Australia–New Zealand candidate core site for the future $2.5bn Square Kilometre Array (SKA) telescope project.

Adapted from information issued by CSIRO. Images courtesy Tim Wheeler and Terrace Photographers.

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Taking the pulse of the universe

Jonathan Nally — Wed, 02 Feb 2011 13:06:51 +0000

Artist's impression of a pulsar, a rapidly spinning neutron star that emits streams of radio waves and sometimes gamma rays.

Pulsars are small, spinning neutron stars
They emit radio waves or gamma rays, and sometimes both
Parkes radio telescope working jointly with NASA space telescope

USING THE PARKES radio telescope, CSIRO astronomers are working closely with NASA to unlock one of astronomy’s great enigmas—the science behind pulsars.

The team are using the world-class facilities at Parkes, in combination with NASA’ s Fermi Gamma-Ray Space Telescope, to understand how these small, spinning stars make their beams of radiation.

The project has tracked down 25 ultra-fast ‘millisecond’ pulsars in just two years—the same number discovered in the previous 20 years.

“This has been a hugely productive collaboration, and it is generating unprecedented returns for physics and astronomy,” said the leader of the Parkes observations, CSIRO’s Dr Simon Johnston.

The study of pulsars demands highly advanced scientific infrastructure and expertise.

Pulsars emit beams of radio waves, gamma waves, or both. Sensitive radio telescopes such as the CSIRO facility at Parkes can detect the radio waves as they sweep across the Earth.

But gamma rays—which carry billions of times more energy than the light our eyes can see—are blocked by the Earth’s atmosphere. We can study them only by using telescopes in space.

Space and ground working together

The CSIRO-NASA collaboration shows we get the best results by combining land and space-based detectors.

First, the Fermi space telescope is finding unidentified gamma-ray sources, which the Parkes telescope can investigate for radio wave pulses.

“That’s how we were able to find those 25 millisecond pulsars, an incredible haul,” Dr Johnston said.

Dr Simon Johnston (foreground) in the control room of CSIRO's Parkes radio telescope.

Second, Parkes is doing very precise timing of 168 radio pulsars that Fermi might be able to study.

“We work out exactly when the pulsar’s radio beam sweeps over us. That tells us how fast the pulsar is rotating,” Dr Johnston said.

“That knowledge helps us make use of the gamma-ray photons that Fermi detects. If Parkes can get the timing precisely right through the radio wave pulses, we can build up a picture of the gamma-ray pulses by collecting a few photons every time the pulsar beam sweeps past.”

Intriguing results

The collaboration has thrown up some intriguing results. Of the 60 objects Fermi has found that emit gamma-ray pulses, about twenty lack detectable radio pulses.

“The most likely explanation is that these pulsars do have radio beams, but they are just not sweeping across the Earth, so we can’t detect them,” Dr Johnston said.

“In other words, we think the beam of gamma rays is a big fat beam, which is easier to detect, and the radio beam is more tightly directed, less spread out.

“This suggests certain things about where on the pulsar the two beams come from, and how they are made. It’s only when we work together that we can crack these long-standing mysteries.”

CSIRO's Parkes radio telescope

International collaboration

Innovation Minister Senator Kim Carr said the research exemplified the sorts of international collaboration that the Australian Government was fostering across the board.

“We have a proud history of cooperation and involvement with NASA on a number of fronts, from assisting with communicating with the Apollo missions to the moon, to deep space exploration, and understanding how our universe works,” Senator Carr said.

“It’s all about exploring new frontiers and building Australian capacity as a research intensive and innovative nation.

“While this might seem remote from everyday life, experience has shown that space exploration in all its forms has unforeseen spin-offs that provide wide-reaching benefits through new technologies and new approaches to a range of challenges.”

Adapted from information issued by CSIRO. Images courtesy CSIRO and NASA.

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‘Russian doll’ galaxy shows black holes’ true power

Jonathan Nally — Mon, 15 Nov 2010 10:10:26 +0000

Artist's impression of a microquasar, a black hole that produces huge jets of particles that 'pump' energy into gas clouds in surrounding space.

“Microquasar” within a galaxy is “powered” by a black hole
Shoots out jets of particles that emit radio waves
Jets pour energy into the clouds of gas that form stars

Following a study of what is in effect a miniature galaxy buried inside a normal-sized one—like a Russian doll—astronomers using the CSIRO’s Compact Array radio telescope have concluded that massive black holes are more powerful than we thought.

The study was made possible by a recent upgrade to the Compact Array, which can now do work of this kind five times faster than before.

The international team of astronomers, led by Dr Manfred Pakull at the University of Strasbourg in France, discovered a ‘microquasar’—a small black hole, weighing only as much as a star—that is shooting jets of radio wave-emitting particles (‘radio jets’) into the space surrounding it.

Called S26, the black hole sits inside a regular galaxy called NGC 7793, which is 13 million light-years away in the Southern constellation Sculptor.

Earlier this year Pakull and colleagues studied S26 with optical and X-ray telescopes (the European Southern Observatory’s Very Large Telescope and NASA’s Chandra space telescope).

Some of the dishes of the Australia Telescope Compact Array.

Now they have made new observations with the Compact Array (near Narrabri, NSW). These show that S26 is a near-perfect mini-version of the much larger ‘radio galaxies’ and ‘radio quasars’.

Powerful radio galaxies and quasars are almost extinct today, but they dominated the early Universe, billions of years ago, like cosmic dinosaurs. They contain big black holes, billions of times more massive than the Sun, and shoot out huge radio jets that can stretch millions of light-years into space.

Escape from a black hole

We often hear that nothing can ever escape from a black hole, so how can these ones shoot out huge jets into space? The answer is that the material does not come from within the black hole itself, but from the region immediately surrounding it.

Because black holes have huge gravitational fields, they tend to attract or suck in lots of gas and interstellar dust. If this material passes the black hole’s ‘point of no return‘, called the event horizon, it will never come out again. But a lot of the material forms into flattened, swirling cloud—what astronomers call an ‘accretion disc’—that surrounds the black hole outside the event horizon.

In the process of falling in toward the black hole, this material gains energy and become very hot. Some of it is then shot out of the region surrounding the black hole, in directions perpendicular to the accretion disc. These are the jets.

Astronomers have been working for decades to understand the precise mechanisms by which the black holes form these giant jets, and how much energy those jets inject into the interstellar gas they travel through. That gas is the raw material for forming new stars, and the effects of the jets on star-formation have been hotly debated.

A composite image showing the position of the 'miniature galaxy' S26 within the galaxy NGC 7793. The inset of S26 is a radio image made with a CSIRO telescope; the 'hotspots' mark the ends of the jets shot out by the black hole (not visible in this picture). The main image of the galaxy is made from combined X-ray and optical data.

There is evidence that the jets help to get a galaxy’s star formation going, and there is counter evidence that jets can suppress the formation of stars. The question is far from settled, and much more work is needed to understand black hole jets.

Jets powered by black holes

“Measuring the power of black hole jets, and therefore their heating effect, is usually very difficult,” said co-author Roberto Soria (University College London), who carried out the radio observations.

“With this unusual object, a bonsai radio quasar in our own backyard, we have a unique opportunity to study the energetics of the jets.”

Using their combined optical, X-ray and radio data set of S26, the scientists were able to determine how much of the jet’s energy went into heating the gas around it, and how much went into making the jet itself visible at radio wavelengths.

They concluded that only about 1/1,000th of the energy went into creating the radio glow.

“This suggests that in bigger galaxies too the jets are about a thousand times more powerful than we’d estimate from their radio glow alone,” said Dr Tasso Tzioumis of CSIRO Astronomy and Space Science.

“That means that black hole jets can be both more powerful and more efficient than we thought, and that their heating effect on the galaxies they live in can be stronger.”

Adapted from information issued by CSIRO / Soria et al / CSIRO / ATCA; NGC 7793 – NASA, ESO and NOAO.

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