Light on the hill

A unique telescope instrument designed by staff at Mt Stromlo, first destroyed in the bushfire of January 2003, has been completed a second time and sent to its new home in Hawaii, where it is set to help make significant astronomical discoveries.

Also in this article:
The Gemini Observatory and NIFS sibling
New view of early universe
Director appointment
Our galaxy: larger than we thought?
ANU astronomer awarded lucrative Fellowship
Comet Deep Impact unlikely

Passing under the radar of global news in space science, the two-tonne, six-sided, optics-packed spectrograph designed by staff at Mt Stromlo is certain to attract international attention in future, with expectations it will be involved in discoveries of galactic proportions.

Known as NIFS — or the Near-infrared Integral Field Spectrograph — it is now at Hawaii’s Mauna Kea Observatory, home of the Gemini North telescope. will be mounted onto the Observatory’s 8.1metre diameter telescope, where it will interpret the light from space more clearly and efficiently than ever before.

The sophisticated spectrograph, which contains more than 29 diamond-machined mirrors (or optics) used to diffuse and direct light beams, will allow astronomers to observe space at a resolution on par with the Hubble Space Telescope. (As a spectrograph, the information from NIFS will be displayed and recorded by computer software in lines, or spectra, rather than photographs.)

The final days before NIFS was shipped represented something of a landmark for the staff of Mt Stromlo, and by extension the University. It closed one of the charred chapters in the history of the Research School of Astronomy and Astrophysics (RSAA), which started with the bushfire of 18 January, 2003.

That fire, which caused significant damage to the observatory at Mt Stromlo, destroyed the completed first iteration of NIFS. One senses an element of understatement when the designer and NIFS project scientist, Dr Peter McGregor, describes as “not nice” the experience of learning that the $6 million telescope component was unsalvageable, and that the whole workshop complex was destroyed.

But then he, like most staff at the RSAA, thinks it is time to move on from the events of January 2003. “NIFS is only one aspect of what was destroyed at Mt Stromlo. But it’s a crucial aspect, being an external contract, so it was highly visible internationally, and was important that we did rebuild it,” Dr McGregor says.

“We were setting records for how quickly we were able to get the instrument going. The fire was, of course, unexpected, and that set us back. But all the drawings and the designs were saved. At the time we had just been awarded a second contract from Gemini to build another instrument, so we were not in a position to be able to rebuild NIFS alone.”

The Director of the Research School of Astronomy and Astrophysics, Professor Penny Sackett, says that NIFS shows how Mt Stromlo continues a tradition of world-class instrumentation to match its reputation for research.

“The completion of this NIFS clearly demonstrates the major contribution of ANU to international astronomical research and technology,” Professor Sackett says.

“The teamwork, innovation, dedication and professionalism that produced the first NIFS and has led to its technical identical twin is testament to a skilled Mt Stromlo team who have invested so much in this project.”

Further confirmation of NIFS sophistication came from the Head of Instrumentation at the Gemini Observatory, Mr Doug Simons, who was at Auspace’s Mitchell headquarters in the days before it began its journey to Hawaii. “There are only a handful of real players in the world when it comes to building an instrument like this, and Mt Stromlo is one of the best,” he said.

ANU scientists and engineers were contracted by the Gemini Observatory in 1999 to design and construct NIFS for the Gemini North Telescope, which is one of the largest looking into space from the northern hemisphere.

After the fires, the University contracted Canberra-based aerospace company Auspace to work with ANU engineers to build a second NIFS, which is the first Australian instrument for the Gemini telescopes.

NIFS is one of the first devices of its kind designed for such a large telescope, making use of cutting-edge optics, Dr McGregor says. Once it is in place, astronomers will be able to study some truly massive phenomena, like the gravitational effects of black holes and the formation of stars. All this will be achieved with an intricate array of tiny mirrors.

“The device works in the near-infrared region, which is just beyond the visible spectrum. It will mounted behind an adaptive optics system on the Gemini telescope, which corrects the image blur produced by the Earth’s atmosphere,” Dr McGregor says.

At NIFS core is an “integral field unit” that uses arrays of 29 diamond-machined metal mirrors to reformat light from the telescope into a long slit pattern that is relayed to the near-infra red spectrograph.

“Essentially, NIFS will take the light from the eight-metre telescope and focus it down onto about a 29 millimetre square region,” Dr McGregor says.

Cooled to below -200 degrees to maintain optimal performance, NIFS will allow detailed study of the mechanics of the universe — not just static photographs, but measurements of the velocities of black holes, gas flows or spin in galaxies.

“For example, if you look at a spiral galaxy, which spins around a nucleus, we’ll be able to measure its motion and then measure how fast it’s rotating,” Dr McGregor said.

“These spinning galaxies often have a black hole operating in the middle of them, too. We’ll be able to see how the material around the black hole is interacting with it. We’ll also be able to study the mass of black holes by observing the movement of stars around them.”

“Then there are also things that are much closer to home, like nearby star forming regions. They tend to have gas flowing into them as well, because they’re building up their mass, and it flows in through a disc, then some of it gets blown out through jets that are coming off these stars as well. So we can look at the jets to understand what the mechanisms are that causes these outflows, because they’re not actually known at the moment.”

These discoveries may also be made by ANU astronomers, with the delivery of NIFS to Gemini North converting into observing time (which is based on the size of the investment by each country in the Gemini consortium).

From one milestone – delivering an Australian designed and built instrument to one of the world’s largest observatories – to the anticipated discoveries in which NIFS will play a crucial part, there is a sense that the RSAA is moving on from the fires.

“We’re now up to a point where we can start to think very seriously about the sorts of science we can do and to start to engage people all over the world to work with us to do that science. That makes the whole project worthwhile. It’s good to see the light at the end of the tunnel,” Dr McGregor says.

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The Gemini Observatory and NIFS sibling

The Gemini Observatory is a partnership of seven countries — Australia, Brazil, Argentina, Chile, Canada, The United Kingdom and the United States.

Gemini operates twin eight-metre diameter optical infrared telescopes — Gemini North on the peak of Mauna Kea in Hawaii, and Gemini South on the Andean peak of Cerro Pachon in Chile

The ANU instrumentation team lead by Dr McGregor is producing Australia’s second project for the Gemini Observatory, which promises to break new ground for Earth-based astronomical observation. The Gemini South Adaptive Optics Imager (GSAOI), designed and built at ANU, is due to be shipped to Chile by the middle of next year. Like its NIFS sibling, the GSAOI will use high-tech optics to correct the blur from the Earth’s atmosphere, but over a much larger area.

“Whereas NIFS just sees a small field, this is a camera that sees a larger field. It will basically take pictures like the ones that you see from the Hubble,“ Dr McGregor says.

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New view of early universe

Astronomers are being provided a rare glimpse back to the time when galaxies were in their infancy

Dr Helmut Jerjen from the Research School of Astronomy and Astrophysics was part of a team that discovered an “Einstein Ring” in the Fornax constellation – only the fourth of its kind ever observed.discovery comes 100 years after Albert Einstein predicted the existence of such tricks of light.

The ring is an optical phenomenon that occurs when two galaxies are perfectly aligned along the line of sight. The gravity of the nearer galaxy acts as a lens, distorting and magnifying the light from its distant counterpart into the shape of a circle.

Dr Jerjen says the closer, lensing galaxy in the Einstein Ring is eight billion light years away and up to 10 times larger than our Milky Way. But he says the farther galaxy is 12 billion light years distant, and would remain invisible if it weren’t for the magnifying effect of the foreground galaxy, allowing a rare insight into the early epoch of galaxy formation of the still young universe.

“We can explore the stellar composition of this distant object, which is a baby galaxy. At 12 billion light years from us, this object is really located at the time when galaxies were just forming. Thanks to these magnified images, we’re able to explore parts of the universe that really wouldn’t be accessible to us otherwise.”

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Director appointment

The Director of the Research School of Astronomy and Astrophysics, Professor Penny Sackett, will be kept busy with her recent appointment to the Association of Universities for Research in Astronomy (AURA) Board of Directors.

AURA is a consortium of over 35 universities, and educational and other non-profit institutions, which operates world-class astronomical observatories.

These include the Gemini Observatories, the National Optical Astronomy Observatory and National Solar Observatories (both in the United States) and the Hubble Space Telescope Science Institute.

AURA also has a New Initiative Office working toward the production of the next generation of optical/IR telescopes. One of the goals of this office is to explore innnovative design options that could reduce production costs. 

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Our galaxy: larger than we thought?

Using the 8-metre Gemini South telescope in Chile, a team of researchers including Professor Ken Freeman from the Research School of Astronomy and Astrophysics, have found evidence that our galaxy could be much bigger than we thought.

Studying the galaxy NGC 300, the team revealed faint ancient outer parts that make it at least twice as big as previously thought. The research was published in the Astrophysical Journal.

NGC300 is a spiral galaxy 6.1 million light-years away. It looks rather like our own galaxy, with most of its stars lying in a thin disk like a pancake.

Our galaxy is estimated to be 100,000 light-years across, about the same as the new estimate for NGC 300. "However, our galaxy is much more massive and brighter than NGC 300. So on this basis, our Galaxy is also probably much larger than we previously thought - perhaps as much as 200,000 light-years across," said the lead author, Professor Joss Bland-Hawthorn, of the Anglo-Australian Observatory.

"We now realise that there are distinctly different types of galaxy disks," Professor Freeman said. "Probably most truncate - the density of stars in the disk drops off sharply. But NGC 300 just seems to go on forever. The density of stars in the disk falls off very smoothly and gradually."

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ANU astronomer awarded lucrative Fellowship

The way the Universe formed 13 billion years ago will be explored as part of an Australian Research Council Federation Fellowship awarded to Professor Brian Schmidt.

Professor Schmidt will seek to understand the basic evolution of the Universe since the time the first stars and galaxies formed as part of the five-year Fellowship, which is worth more than $1 million.

Professor Schmidt leads the Southern Sky Survey at Mt Stromlo, the first all-sky digital survey of the southern skies using the hi-tech Skymapper telescope.

During his career, he has been awarded the Harvard Bok Prize, the inaugural Australian Malcolm McIntosh Prize and the Australian Academy of Science Pawsey Medal, among others.

He was named Australia's top scientist in 2004 by Bulletin magazine in its annual Smart 100 list.

Professor Schmidt is the second Federation Fellow at Mt Stromlo - Professor Mike Dopita was an inaugural Australian Federation Fellow.

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Comet Deep Impact unlikely

The chances of the Earth being hit by a comet from beyond Pluto — á la Deep Impact — are much lower than previously thought, according to new research by an ANU astronomer.

Using computer simulations and data from an American military telescope, Dr Paul Francis, from the ANU Research School of Astronomy and Astrophysics at Mt Stromlo, has found there are seven times fewer comets in our solar system than previously thought.

“I calculate that small comets, capable of destroying a city, only hit the Earth once every 40 million years or so,” Dr Francis said. “Big continent-busting comets, as shown in the movie Deep Impact, are rarer still, only hitting once every 150 million years or so. So I don’t lose sleep over it, but you’re still more likely to be killed by a comet than to win the Lotto jackpot.”

Previous estimates of the number of comets were based on the work of amateur astronomers, who for hundreds of years have been scanning the skies, looking for new comets.

Previously, it was believed that these amateur astronomers were only spotting three per cent of the comets passing close to the Earth: the rest were thought to be missed because they were in the wrong part of the sky or were too faint.

But Dr Francis found that the amateurs were doing better than anyone had realised — they were actually spotting 20 per cent of comets. There are therefore far fewer undiscovered comets.

“The new data allowed us to count the number of faint and far-away comets that the amateurs had missed. And we found that they were pretty rare,” Dr Francis said.

These results apply to comets coming from beyond the orbit of Pluto, which is where most comets live. The Earth is still at risk of being hit by asteroids, and by so-called short-period comets — ones that come past repeatedly, like Halley’s comet.

“But asteroids and short-period comets come past again and again, so if we’re clever enough we can find them all and predict which, if any, will hit the Earth,” said Dr Francis. “If we find one on a collision course with the Earth, we would normally have hundreds of years warning in which to do something about it, like deflecting the asteroid.

“The comets coming from beyond Pluto, so called long-period comets, are nastier, as they are totally unpredictable, and if we see one on a collision course we’d have at best one or two years warning – not long enough to do anything.”

Dr Francis’ research has been accepted for publication in the Astrophysical Journal. It was based on computer simulations, published data from the Lincoln Near Earth Asteroid Research Project at White Sands Missile Range in New Mexico, and on data from amateur astronomers around the world.

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