RSSAll Entries Tagged With: "radio astronomy"

Australian astronomer wins prestigious award

THE 2014 GROTE REBER MEDAL for innovative and significant contributions to radio astronomy has be awarded to Professor Ron Ekers of Australia. Professor Ekers was the Foundation Director of CSIRO’s Australia Telescope National Facility at Narrabri, and is a former director of the Very Large Array in New Mexico, USA, operated by the National Radio Astronomy Observatory (NRAO).

He is currently a CSIRO Fellow at the Australia Telescope National Facility (ATNF), CSIRO Division of Astronomy and Space Science in Australia, and Adjunct Professor at Curtin University in Perth and the Raman Research Institute in Bangalore, India.

Headshot of Ron Ekers

Professor Ron Ekers

The Grote Reber Medal is named after a pioneer of radio astronomy (see below).

Ekers is being recognised for his many pioneering scientific radio astronomy investigations, which extend over half a century. Working with various colleagues, Ekers studied galaxies, made precise measurements of the way the Sun’s gravity deflects radio waves, made some of the first high-resolution images of the centre of the Galaxy at radio wavelengths, and critical early observations of pulsars.

More recently he is leading a project to detect radio emission resulting from ultra high-energy neutrino interactions with the Moon.

Ekers also played a key role in developing what was probably the first interactive computer language for analysing radio astronomy images. In the mid-1990s he became the strongest force in advocating support for the international Square Kilometre Array initiative.

“Over a career lasting nearly half a century Ron Ekers has worked in almost every area of radio astronomy. As a strong believer in international collaboration, he was the earliest advocate for the Square Kilometre Array, and perhaps, more than anyone else, he was responsible for building the current level of international support for the SKA”, said Dr Ken Kellermann of the NRAO.

“Ron is the complete internationalist and has contributed significantly to the major radio astronomy instruments in Europe, the US and Australia,” said Dr David Jauncey, CSIRO Astronomy and Space Science Affiliate and ANU Visiting Fellow.

The medal will be presented to Professor Ekers during the 31st General Assembly of the International Union of Radio Science to be held in Beijing, China in August, 2014.

About Grote Reber

Grote Reber was born on 22 December 1911. Before he was 30 years of age, he became the world’s first radio astronomer. In 1937, constructed the world’s first purpose-built radio telescope, adjacent to his home in Wheaton, Illinois, just west of Chicago. Reber’s telescope was the forerunner of the classic design of the world’s famous radio telescopes (including the famous ‘dish’ at Parkes, in Australia). The same principle is used widely today in many other applications, including satellite dishes in private homes.

Reber used his telescope to make the first detailed radio map of the sky. “His work was a huge step forward for astronomy”, said Martin George, Administrator of the Grote Reber Medal. “For the first time, the Universe was being studied at wavelengths other than those visible to our eyes.”

Grote Reber using radio equipment

Grote Reber

In 1954, Reber moved to Tasmania, Australia, where he began observing at very much longer wavelengths using a quite different type of ‘telescope’: an array of dipoles, which took the form of antennas strung between the tops of poles.

Reber constructed an array that covered an area of one square kilometre. Although now dismantled, in terms of collecting area it still holds the record for the world’s largest single radio telescope ever constructed.

Although Reber’s research and ideas often fell outside the mainstream activities of other astronomers, his contributions, especially in the early days of radio astronomy, were both pioneering and critically important. He was awarded a number of prizes and an honorary Doctor of Science Degree from Ohio State University in the USA.

“Grote Reber’s achievements showed, most importantly, that one person can make a difference”, said Dr David Jauncey.

Grote Reber died in Tasmania on 20 December 2002, two days before his 91st birthday.

Adapted from information issued by Trustees of the Grote Reber Foundation. Ron Ekers and ATCA photos courtesy of CSIRO Astronomy and Space Science. Grote Reber photo courtesy NRAO.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

SKA telescope to be split

Artist's impression of SKA dishes

Artist's impression of SKA dishes.

IT HAS JUST BEEN ANNOUNCED that the international Square Kilometre Array (SKA) radio telescope system, will be hosted jointly by the two bidding regions – Australia-New Zealand and South Africa. The SKA will comprise around 3,000 antennae of different types to cover low-, mid- and high-frequency ranges.

Following is the text of the announcement made by the SKA organisation:

The Members of the SKA Organisation today agreed on a dual site solution for the Square Kilometre Array telescope, a crucial step towards building the world’s largest and most sensitive radio telescope.

The ASKAP (Australian Square Kilometre Array Pathfinder) and MeerKAT precursor dishes will be incorporated into Phase I of the SKA which will deliver more science and will maximise on investments already made by both Australia and South Africa.

The majority of the members were in favour of a dual-site implementation model for SKA. The members noted the report from the SKA Site Advisory Committee that both sites were well suited to hosting the SKA and that the report provided justification for the relative advantages and disadvantages of both locations, but that they identified Southern Africa as the preferred site. The members also received advice from the working group set up to look at dual site options.

The majority of SKA dishes in Phase 1 will be built in South Africa, combined with MeerKAT. Further SKA dishes will be added to the ASKAP array in Australia. All the dishes and the mid frequency aperture arrays for Phase II of the SKA will be built in Southern Africa while the low frequency aperture array antennas for Phase I and II will be built in Australia.

“This hugely important step for the project allows us to progress the design and prepare for the construction phase of the telescope. The SKA will transform our view of the Universe; with it we will see back to the moments after the Big Bang and discover previously unexplored parts of the cosmos,” says Dr Michiel van Haarlem, Interim Director General of the SKA Organisation.

The SKA will enable astronomers to glimpse the formation and evolution of the very first stars and galaxies after the Big Bang, investigate the nature of gravity, and possibly even discover life beyond Earth.

“Today we are a stage closer to achieving our goal of building the SKA. This position was reached after very careful consideration of information gathered from extensive investigations at both candidate sites,” said Professor John Womersley, Chair of the SKA Board of Directors. “I would like to thank all those involved in the site selection process for the tremendous work they have put in to enable us to reach this point.”

Factors taken into account during the site selection process included levels of radio frequency interference, the long term sustainability of a radio quiet zone, the physical characteristics of the site, long distance data network connectivity, the operating and infrastructure costs as well as the political and working environment.

The agreement was reached by the Members of the SKA Organisation who did not bid to host the SKA (Canada, China, Italy, the Netherlands and the United Kingdom). The Office of the SKA Organisation will now lead a detailed definition period to clarify the implementation.

Scientists and engineers from around the world, together with industry partners, are participating in the SKA project which is driving technology development in antennas, data transport, software and computing, and power. The influence of the SKA project extends beyond radio astronomy. The design, construction and operation of the SKA have the potential to impact skills development, employment and economic growth in science, engineering and associated industries, not only in the host countries but in all partner countries.

About the SKA

The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10,000 times the survey speed, of the best current-day telescopes.

Thousands of receptors will extend to distances of 3,000 km from the centre of the telescope, the SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the big bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth.

The target construction cost is €1,500 million and construction of Phase 1 of the SKA is scheduled to start in 2019. The SKA Organisation, with its headquarters in Manchester UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

Members of the SKA Organisation:

Australia: Department of Innovation, Industry, Science and Research

Canada: National Research Council

China: National Astronomical Observatories, Chinese Academy of Sciences

Italy: National Institute for Astrophysics

New Zealand: Ministry of Economic Development

Republic of South Africa: National Research Foundation

The Netherlands: Netherlands Organisation for Scientific Research

United Kingdom: Science and Technology Facilities Council

Associate member:

India: National Centre for Radio Astrophysics

Images courtesy SPDO / Swinburne Astronomy Productions.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Revolutionary new telescope in WA

MWA antennae

Antennae of the Murchison Widefield Array (MWA) in the Murchison Radio-astronomy Observatory, Western Australia. Credit: Dr Natasha Hurley-Walker (ICRAR).

A QUEST TO STUDY the earliest stars and galaxies in the Universe is underway, with local industry building the first major pieces of a revolutionary new radio telescope in Western Australia, as part of the Murchison Wide-field Array.

Murchison Wide-field Array (MWA) industry partner and Fremantle-based high-technology company, Poseidon Scientific Instruments (PSI), has been awarded a $1.3m contract by Curtin University to build 16 packages of sensitive electronics, using a smart design suited to the environmental and radio-quiet conditions of outback WA.

The MWA is located at the Murchison Radio-Astronomy Observatory, a site operated by CSIRO and a proposed core site for the multi-billion dollar Square Kilometre Array (SKA).

The MWA will be the first of three official SKA precursor telescopes to be completed, proving the technology and science on the path to the SKA.  Australia and New Zealand are bidding to host the SKA, with the site location to be decided in February 2012.

MWA site

The desolate landscape of outback Western Australia is perfect for radio astronomy.

The MWA is being built by an Australian consortium led by The International Centre for Radio Astronomy Research (ICRAR), a joint venture between Curtin University and The University of Western Australia, in close collaboration with US, Indian and New Zealand partners.

ICRAR Deputy Director, Professor Steven Tingay, said PSI was a world-class technology company and working with its local expertise to design and develop components for the international project was an enormous advantage.

“PSI will build 16 electronics packages for the MWA, the culmination of more than two years of collaboration in which PSI have been deeply involved in the design cycle. They are a valued collaborator, not just another cog in the supply chain,” Professor Tingay said.

The innovative package would also prevent the electronics from interfering with other equipment on the site, preserving the uniquely radio-quiet environment of the Murchison.

“The combination of the MWA and the radio-quiet environment of the Murchison will allow us to search for the incredibly weak signals that come from the early stages in the evolution of the Universe, some 13 billion years ago,” Professor Tingay said.

One of ICRAR’s goals is to partner with Australian industries to help position them to participate in future radio astronomy opportunities, such as the SKA. The MWA partnership with PSI is one such success story.

Adapted from information issued by ICRAR. Panorama image by Paul Bourke and Jonathan Knispel (supported by WASP (UWA), iVEC, ICRAR, and CSIRO).

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Milky Way galaxy is a ‘snake pit’

CSIRO's Australia Telescope Compact Array

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.)

Gas turbulence map of part of the Milky Way

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.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Join the SkyNet Project!

theSkyNet logo

TheSkyNet is a new citizen science project that lets you use your computer's spare power to help radio astronomers explore the Universe.

A COMMUNITY COMPUTING SCIENCE initiative to help discover the hidden Universe was officially launched this morning at Curtin University by Western Australia’s Minister for Science and Innovation, the Hon. John Day.

TheSkyNet project, sponsored by the WA Department of Commerce and developed by the International Centre for Radio Astronomy Research (ICRAR), in conjunction with UK-based computing company, eMedia Track, will enable members of the public to contribute their spare computing power to the processing of radio astronomy data.

ICRAR Director, Professor Peter Quinn, said theSkyNet provided a community-based cloud computing resource to raise awareness of the Square Kilometre Array (SKA) project and complement the primary data processing work of supercomputing facilities such as the Pawsey Centre.

“Radio astronomy is a data intensive activity and as we design, develop and switch on the next generation of radio telescopes, the supercomputing resources processing this deluge of data will be in increasingly high demand,” Professor Quinn said.

A nebula

Your spare PC power can help crunch the data from radio telescopes

TheSkyNet aims to complement the work already being done by creating a citizen science computing resource that radio astronomers can tap into and process data in ways and for purposes that otherwise might not be possible.”

Help explore the Universe

Curtin University’s Acting Vice-Chancellor, Professor Graeme Wright, said theSkyNet would generate real outcomes for scientific research by encouraging the online community to participate in the processing of radio astronomy data.

“Radio astronomy is a clear focal point in Curtin’s commitment to research in ICT and emerging technologies and it’s great to see people from across the University, in collaboration with our partners at the Department of Commerce, The University of Western Australia and ICRAR, bringing this project to life,” Professor Wright said.

ICRAR Outreach Manager, Pete Wheeler, said joining theSkyNet allowed participants to play a major part in the exploration of the Universe.

“By creating a distributed network containing thousands of computers, we can simulate a single powerful machine capable of doing real scientific research,” Mr Wheeler said.

“The key to theSkyNet is having lots of computers connected, with each contributing only a little, but the sum of those computers achieving a lot.”

For further information and to sign up, please visit theSkyNet website:

Adapted from information issued by Curtin University.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Galaxies are running out of gas

A star-forming region

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.”

Mopra radio telescope

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.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Radio astronomy protected in Western Australia

Artist's impression of dishes that will make up the SKA radio telescope.

Artist's impression of dishes that will make up the SKA radio telescope.

ENHANCED PROTECTIONS are now in place for the Mid West Radio Quiet Zone (RQZ) in remote Western Australia (near Boolardy Station), around 200 kilometres east of Meekatharra…a candidate site for the proposed Square Kilometre Array (SKA).

The RQZ was established in 2005 to provide an environment that protects highly sensitive equipment used for radio astronomy from unwanted radio communications signals.

These arrangements protect the radio telescopes currently in place at the Murchison Radioastronomy Observatory—such as the Australian SKA Pathfinder (ASKAP) and the Murchison Wide-field Array (MWA)—as well as those proposed in the Australian-New Zealand bid to host the SKA.

ASKAP dish

One of the Australian SKA Pathfinder (ASKAP) dishes.

“A clear regulatory framework to support radio quiet arrangements will further assist Australia to create the world’s best radioastronomy facility,” said Australian Communications and Media Authority (ACMA) Chairman, Chris Chapman.

“This will provide a platform that should be ideal for future radioastronomy projects, including the €1.5 billion SKA project.”

Mr Chapman said the new protection measures provide greater clarity and certainty to the arrangements that protect radio astronomy services in the RQZ.

‘The new measures continue to provide for radio quiet while supporting the use of spectrum by other users and placing the lowest feasible burden on industry in the region,’ said Mr Chapman.

The introduction of the enhanced protections for the RQZ follows a very extensive consultation process in which the ACMA sought the views of interested stakeholders.

More information: ACMA Planning for the radio astronomy service

Adapted from information issued by ACMA. Images courtesy SPDO / Swinburne Astronomy Productions / CASS / Terrace Photographers.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Milestone as radio dishes linked

ASKAP antennae

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.

Map of antennae across Australia and New Zealand

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.

Radio image of a quasar

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.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Milky Way spreads its arms

Diagram showing possible new Milky Way spiral arm

The Milky Way's basic structure is believed to involve two main spiral arms emanating from opposite ends of an elongated central section. But only parts of the arms can be seen—grey segments indicate portions not yet detected. (Other known spiral arm segments, including the Sun's own spur, are omitted from this diagram for clarity.)

OUR MILKY WAY GALAXY, like other spiral galaxies, comprises a main flattened body (or “disc”) with sweeping arms of stars, gas, and dust that curve around the galaxy like the arms of a huge pinwheel.

Our Solar System is located in a “spur” or offshoot that lies between two of the spiral arms, collectively orbiting around the galaxy about 25,000 light-years from its centre.

But because the Milky Way contains huge amounts of dust that blocks our view at normal optical wavelengths, it is extremely difficult to gauge the shape of the galaxy from our vantage point within the disc. It’s like trying to determine the overall shape of forest when you’re stuck in the middle.

This means that our knowledge of our galaxy’s spiral arms is much less certain than that of other galaxies such as Andromeda … because even though Andromeda is million light-years away, we have the advantage of seeing it from the outside.

Radio telescopes can peer through the dust, however, and molecules like carbon monoxide that emit radio wavelengths and concentrate in the Milky Way’s spiral arms, are particularly good “tracers” of the arms’ structure.

Using a small 1.2-metre radio telescope on the roof of their science building in Cambridge, Massachusetts, Harvard-Smithsonian Centre for Astrophysics astronomers Tom Dame and Pat Thaddeus used carbon monoxide emission to search for evidence of spiral arms in the most distant parts of the Milky Way, and discovered a large, new spiral arm peppered with dense concentrations of molecular gas.

They suggest that the new spiral is actually the far end of the Scutum-Centaurus Arm, one of the two main spiral arms thought to originate from opposite ends of our galaxy’s central section.

If their findings are confirmed, it will demonstrate that the Milky Way has a striking symmetry, with the new arm being the counterpart of the nearby Perseus Arm.

Adapted from information issued by the Harvard-Smithsonian Centre for Astrophysics. Image courtesy T. Dame.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Dish complex will study ‘cool’ cosmos

First eight ALMA dishes

The first eight ALMA dishes have already been pressed into service, 5,000 metres above mean sea level on the Chajnantor plateau in Chile. They are seen here in September 2010.

A GIANT NETWORK OF RADIO DISHES is taking shape high in the deserts of the Atacama Plateau in Chile. Known as the Atacama Large Millimetre/Submillimetre Array (ALMA), it will be used to study the ‘coolest’ parts of the cosmos.

When completed, ALMA will comprise 66, twelve-metre-diameter antennae, each weighing about 95 tonnes. The dishes will be electronically joined to form one single, huge telescope that picks up millimetre and submillimetre wavelengths from deep space.

These wavelengths are affected by water vapour in the atmosphere, which explains the choice of the high and dry site in the Atacama.

As each dish arrives from the manufacturer, it is moved on a special transporter from the Site Erection Facility (SEF) where it is assembled and tested, to the Operations Support Facility (OSF), where it is fitted with its extremely sensitive radio receivers and cooling systems.

Artist's impression of the finished ALMA

Artist's impression of the finished ALMA network of 66 dishes.

Both the SEF and OSF are at an elevation of 2,900 metres above mean sea level, which seems high enough. But the antennae’s final resting place is the observatory site on the Chajnantor plateau, which is at 5,000 metres elevation.

Cool cosmos

ALMA’s targets are the ‘coolest’ components of the universe…the tiny particles of interstellar dust and gas molecules from which everything—stars, planets and galaxies—formed and are still forming.

The array will be able to peer back in time to reveal some of the earliest galaxies, when the universe was only a few billion years old. It’ll also provide information on the formation of stars and planetary systems in the closer and more recent universe.

ALMA dish on a transporter vehicle

The ALMA antennae each weigh about 95 tonnes, and are moved around on giant transporter vehicles.

The dishes are state-of-the-art, with surface panels built and aligned to a precision of less than the thickness of a human hair. Theoretically, ALMA could spot a golf ball 15 kilometres away.

Conditions on the Chajnantor plateau are tough, with strong sunlight and fierce winds. None of the dishes have protective domes, and the air temperature can drop to –20 degrees Celsius.

ALMA is an international facility, being a partnership of Europe, North America and East Asia working collaboratively with the host country, Chile. Twenty-five antennae are being provided by Europe, 25 by North America and 16 by East Asia.

Story by Jonathan Nally, copyright Images courtesy ALMA and (ESO/NAOJ/NRAO), J. Guarda.

Get daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…