Past Issues

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Roberto Abraham doesn't mind telling you about his plans to cheat. The winner of a 2005 Steacie Fellowship from the Natural Sciences and Engineering Council of Canada isn't conspiring to do anything reckless, however. For Abraham, cheating means using today's technology to find "First Light."

Roughly 14 billion years ago, it took the Big Bang three minutes to create all the hydrogen and helium found in our universe. The next 800 million years were relatively quiet until "something" blasted all the universe's hydrogen with energy, setting off a chain reaction that led to the creation of the galaxies of stars we see in the cosmos. This mysterious something is called First Light - and Abraham wants a head start in finding it.

Different wavelengths of lights - visible, ultraviolet or infrared - expose different layers of the material. With the naked eye, security or customs authorities see a photograph, but when illuminated with other types of light, signatures or fingerprints can be seen. "Everything is recorded on the same spot, but we go deep into the bulk of the film where you can add a new photo every five to 10 years," explains Kumacheva. "You can store a person's photos over 50 years. It's very difficult to counterfeit."

In 2013 the James Webb Space Telescope (JWST) will be launched, carrying on from the Hubble Space Telescope's 20-year run. It's anticipated the JWST, with a primary mirror more than three times the size of its predecessor, will make short work of capturing the highly-coveted image of First Light. But Abraham would rather get to it sooner - and from the ground.

"The JWST will get the job done right. Even if we get there from the ground first, we'll need it to characterize whatever it is we find. I'm really looking to get a quick start on the early work that we can build on with the JWST."

Astronomers are able to see objects incredibly far from Earth using telescopes to capture light or photons. Light's speed is finite - travelling 300,000 kilometres per second, or 10 trillion kilometres per year. Bigger mirrors capture photons emitted from farther distances, allowing astronomers to essentially see back in time. Since Abraham can't yet make use of the JWST's mirror, he's devised a strategy for cheating.

Utilizing the infrared spectrum, which measures heat radiation, is one way that Abraham hopes to see processes undetectable in visible light. And by enlisting the help of nature, he plans on examining certain preferred areas in space that are magnified by gravitational lenses - regions that are sufficiently dense with gravitating material that they perceptibly bend light, making objects far away appear brighter than they really are. Using his Steacie funding, Abraham is constructing a novel instrument, the F2T2, to look at these preferred locations in the universe.

He is also taking advantage of adaptive optics technology, which compensates for distortions in light caused by the Earth's atmosphere. Using the eight-metre Gemini Twin Telescopes located in the Chilean Andes and atop Mauna Kea, Hawaii, currently the premier telescopes in the world for this technology, Abraham says, "The plan is to obtain results that are almost as good as those taken from space."

Although the discovery of First Light is in many ways the holy grail of current observational astronomy, Abraham believes it will probably lead to more questions than answers.

"We have to approach this humbly and listen to what Mother Nature tells us. But I don't want to spend the next 10 years waiting to hear what she has to say. I want to take what I've learned and apply it today."


In 1998, as a graduate student at Harvard University, Ray Jayawardhana led a team that discovered a disk of debris - a dusty ring that appeared to be the left-over of a newly formed planetary system - around a star in the constellation Centaurus. The discovery landed the team's work on the cover of Newsweek. In 2006, Jayawardhana (pictured on cover), a U of T professor, and a much sought-after science writer and contributing editor to Astronomy Magazine, is continuing his investigation into how planets and stars form.

Stars are born when clouds of gas and dust particles contract under gravity and reach high enough temperatures and pressures in their cores to activate nuclear reactions - the energy process that causes their glow. These young stars are often surrounded by disks of dusty material, which, astronomers believe, have the potential to spawn planets.

For the most part, however, there are still many unanswered questions about the birth and diversity of planetary systems.

Jayawardhana believes that some clues may lie with brown dwarfs. "Brown dwarfs are sometimes called failed stars, because they are not hefty enough to be stars, but they are a bit more massive than planets." In the past five years, hundreds of brown dwarfs have been identified, some in pairs. Jayawardhana has been studying brown dwarfs, which, like stars, also have disks that may contain planet-forming material.

Two years ago, while at the University of Michigan, Jayawardhana started to explore the idea that brown dwarfs and stars are born in similar ways. "According to some recent theories, stars form in litters of four to six. As they whiz about, encounters with the bigger siblings kick the smallest embryos out of the litter." Since brown dwarfs often come in pairs, Jayawardhana says the theory cannot account for all brown dwarfs. "If brown dwarfs were ejected from the litter, they wouldn't remain in these binary systems that we find some of them in."

Today, Jayawardhana has his sights on planets outside of our solar system. It's been 10 years since astronomers detected the first of these "exoplanets." Today, nearly 160 planets - comparable in size to giants Jupiter and Saturn - have been detected around nearby sun-like stars.

For Jayawardhana, examining this new frontier is an opportunity to push the limits of our knowledge of star and planet formation. "We're looking at stars in different phases of growth to see how they evolve. We're using these snapshots to unravel the story of how dusty disks around young stars grow into mature planetary systems."

Almost all of these exoplanets have been indirectly detected, but last year, a European team obtained the first confirmed photograph of a "planetary-mass companion" of a brown dwarf about 25 times the mass of Jupiter. Jayawardhana had been studying the brown dwarf and its disk for a couple of years prior to the discovery, and is about to publish new findings on the nature of its planetary mass companion.

"Based on what we know, it's unlikely that this planet formed out of the disk around the brown dwarf. Instead, the two most probably formed like a pair, as binary brown dwarfs." Still, it does have planet-type characteristics, which Jayawardhana says has raised new questions on extrasolar planet formation. "We're really just at the beginning of understanding their diversity and origin."


Brown dwarfs are not the only celestial objects to exist in pairs. Marten van Kerkwijk is following a hunch that since many stars are found in binary systems, companionship is actually important to their formation.

"The larger the star is, the more likely it is to have a companion," explains van Kerkwijk. "With stars the size of the sun, there's roughly a 50 per cent chance that they will have a companion star, whereas almost all stars 10 times more massive than the sun have at least one companion."

Stars are born inside clouds made up of dense concentrations of gas and dust. A star's actual formation, however, does not begin until the denser parts of the cloud collapse and fragment into a protostar - which is five times larger than the finished product.

Binary stars are often found orbiting very close to one another, prompting van Kerkwijk to posit questions on what could influence this close habitation.

"When you have two stars that are almost touching, you wonder what they were like when they were five times bigger." That at one time two stars could exist inside each other isn't likely, says van Kerkwijk. "If that was the case, they would just merge and become one star."

One possible idea is that a third star, a culprit of sorts, can disturb the orbit of the two stars. Van Kerkwijk is testing this theory by searching for signatures of these third stars in observations made by Slavek Rucinski, associate director of U of T's David Dunlap Observatory.

Van Kerkwijk looks at all aspects of a star's lifespan, including its death. When a large star dies, it does so in a supernova, an explosion so bright that it often shines brighter than the galaxy the star resided in. What's left of the star's collapsed core is reborn as a neutron star, an object almost as dense as a black hole - a small region of space with a gravitational field so powerful that it emits no light. Many neutron stars may, in fact, eventually collapse into black holes.

"A neutron star is much denser than the nucleus of an atom, the densest matter on Earth," says van Kerkwijk. "My goal is to understand how they work inside."


The examination of individual stars is amplified by the billions in Howard Yee's work. Yee is conducting the slow and methodical work of surveying galaxy clusters, which are hundreds and thousands of galaxies bound together by gravity.

To illustrate the magnitude of these structures, Yee pulls up a computer image of what looks like hundreds of colourful fireflies circling in a night sky. Pointing to a cluster of yellow spots, he says, "Each one of these is a galaxy like our own and each contains anywhere from 10 billion to 100 billion stars."

To locate galaxy clusters, the Canada Research Chair in Observational Cosmology is searching a massive region of space. Building on the Red Sequence Cluster (RSC) 1 project, which looked at 100 square degrees of the sky, Yee has increased his scope tenfold with RSC2, a survey of 1,000 square degrees. Yee offers an analogy for the size of his research domain. "The moon is a quarter square degree. The area we're looking at is the size of 4,000 moons."


Using a digital camera mounted on the Canada-France-Hawaii Telescope on Mauna Kea, Yee will shoot about 1,000 pictures of galaxies as far as eight to nine million light years away. From there, he and his collaborators will begin the work of identifying concentrations of galaxies, mapping their distance from Earth and measuring their size. The result? A census of about 30,000 galaxy clusters that promises to shed light on one of the biggest mysteries in astronomy.

In the late 1990s, astronomers discovered dark energy, a type of material equipped with a negative energy so powerful that it shoves galaxies away from each other at ever-increasing speeds. Prior to its discovery, it was generally accepted that the expansion of the universe that began with the Big Bang would slow down due to gravity. Dark energy has indicated, at least theoretically, that the expansion of the universe will go on forever. But the mysterious substance that makes up approximately 70 per cent of all material in the universe can't be seen. Its existence is only known by the affect it has on galaxies.

By measuring the density of galaxy clusters at varying distances from Earth, Yee hopes to gain insight into dark energy's equation of state - the relationship between its density and pressure.

"A different ratio between dark energy's pressure and density causes the universe to expand at slightly different rates. This involves finding tens of thousands of galaxy clusters to see how their density changes at different points in time. From there, we'll be able to infer something about the properties of dark energy.

"Ultimately, it will be a long time before we can fully understand dark energy. At the moment, we only see its effect. Finding these galaxy clusters will hopefully help us solve the mystery."




Ray Carlberg:
The time is right for the
Thirty-Metre Telescope

It's big, it's expensive, and in 2015, it will allow astronomers to see farther into the universe than ever before. The Thirty-Metre Telescope (TMT) will be the largest ground-based telescope ever built. It will have nine times the light-gathering power of the 10-metre Keck Telescopes in Hawaii, currently the largest in the world. And with its adaptive optics technology, the TMT will produce images 12 times sharper than those shot by the Hubble Space Telescope.

For U of T's Ray Carlberg, the Canadian lead on the project, the unveiling of the TMT will be a giant leap toward his goal of equipping Canadian astronomers with the tools to conduct leading-edge research.

In 2003, a partnership between four groups - the Association of Canadian Universities for Research in Astronomy, the California Institute of Technology, the University of California, and the (US) Association of Universities for Research in Astronomy - made the commitment to build the TMT.

The Canada Foundation for Innovation agreed to a start-up grant, with provincial support, to the tune of $10 million. This support has enabled Carlberg and the Canadian team to get to the TMT table, but the project as a whole still has a long way to go. With an estimated budget of US$700 million, the four partners have raised the $65 million required for the project's detailed design phase.

The TMT will combine its immense size with extreme precision. Rather than constructing a massive mirror 30-metres wide, engineers will use approximately 800 hexagon-shaped mirrors to create one large mirror the size of a hockey rink. Its sophisticated adaptive optics technology will compensate for distortions caused by the Earth's atmosphere, and it will be equipped to gather light from both visible and infrared wavelengths.

It's anticipated that the TMT will generate an avalanche of new ideas in astronomy and astrophysics. One of the team's main goals hinges on the James Webb Space Telescope, the successor to the Hubble set to launch in 2013. The two will work in conjunction, allowing astronomers to travel back over 13 billion years to the birth of the first stars in our universe.

"The time is right for the TMT," says Carlberg, citing that it's been 10 years since the first planet outside of our solar system has been discovered, and dark energy - a startling mystery that makes up 70 per cent of the entire universe - is barely understood.

"Current large ground-based telescopes have allowed astronomers only a small glimpse at the origins of our universe. The TMT will allow us to take the study of planets from discovery through to the characterization of their properties, and give us insights into the origins of galaxies, star and planets."



 
     
University of Toronto Office of the Vice-President, Research and Associate Provost