Astronomers snap first photos of 'exoplanets'
Canadian and American astronomers have finally photographed the first planets ever actually seen around distant stars.
By Ottawa Citizen
OTTAWA - Canadian and American astronomers have finally photographed the first planets ever actually seen around distant stars.
Four of them at once and they're visible because they glow. While dozens of planets are known to exist around stars other than our sun, none have ever been visible until now.
Instead, astronomers figured out where they are and what they weigh by noticing how each planet's gravity pulls at its own star, making the star wobble. It's like a large adult swinging a child in circles - the child's weight makes the adult lean to balance it.
But now there are photos of "exoplanets."
Canadians from the National Research Council photographed three bright planets around a single star in the constellation Pegasus, with help from the Universite de Montreal and University of Toronto. It's a very young star in astronomy terms: At 60 million years of age, the star and its planets formed after the dinosaurs on Earth were already extinct.
And working independently, the Hubble Space Telescope captured two images of another planet. A team from the University of California at Berkeley found a dim spot in a cloud of hot dust and debris orbiting a star 25 light-years from us called Fomalhaut. It is a planet the size of Jupiter orbiting its star at very long distance - 17 billion kilometres.
The studies were published Thursday in Science, a research journal.
"It was completely different discoveries," said Christian Marois of the National Research Council's Herzberg Institute of Astrophysics in Victoria, leader of the three-planet team. "They were made roughly at the same time."
He says "roughly" because finding a planet is never a sudden, one-day discovery.
A dim spot appears in a photo, people stare at it, wonder what it could be, take more pictures, eventually decide it probably isn't a star, and wait for months "to make sure the object is moving with its star. If they move together, that means it's a gravitationally-bound object."
The Hubble, Keck and Gemini telescopes that produced these photos are not new, but Marois said a change in the searching method, rather than new technology, made the breakthrough.
Recently, there's been a trend to looking at bigger stars, hoping they will have more, and bigger, planets. A very large planet isn't easier to see just because of its size, but because it's probably young, hot and probably glowing.
The planets studied by the Marois group may be 500 to 800 Celsius.
As well, the planet around a very big star may orbit at a great distance from it. And being farther from its star makes it easier to see; planets close to a star are lost in the glare.
"We are actually seeing photons, light, from the planet itself. The fact that the system is young, they (planets) are still glowing from a lot of the energy they had accumulated," he said.
Team member Bruce Macintosh of the U.S. Lawrence Livermore National Laboratories adds: "Until now, when astronomers discover new planets around a star, all we see are wiggly lines on a graph of the star's velocity or brightness. Now we have an actual picture showing the planets themselves, and that makes things very interesting."
Photos will show what former detection methods cannot.
Peter Brown of the University of Western Ontario said in an e-mail: "You may get (in principle) a complete orbit, size, mass and possibly a density which allows you to tell things about the planet (is it stony like the Earth or a gas giant?)"
He said photos may also reveal what gases are in the atmosphere.
Meanwhile, Marois added: "The star is in the constellation of Pegasus, so people can get out and see it tonight."
It's a very dim star, barely visible with the naked eye from a very dark location.
Coincidentally, Pegasus is also the constellation where the first planet outside our solar system was discovered (though not seen) back in 1995. It orbits a star called 51 Pegasi.
Marois's group is still studying two other candidates - each one star with a single possible planet - but won't know what's there for certain for several months.
Four of them at once and they're visible because they glow. While dozens of planets are known to exist around stars other than our sun, none have ever been visible until now.
Instead, astronomers figured out where they are and what they weigh by noticing how each planet's gravity pulls at its own star, making the star wobble. It's like a large adult swinging a child in circles - the child's weight makes the adult lean to balance it.
But now there are photos of "exoplanets."
Canadians from the National Research Council photographed three bright planets around a single star in the constellation Pegasus, with help from the Universite de Montreal and University of Toronto. It's a very young star in astronomy terms: At 60 million years of age, the star and its planets formed after the dinosaurs on Earth were already extinct.
And working independently, the Hubble Space Telescope captured two images of another planet. A team from the University of California at Berkeley found a dim spot in a cloud of hot dust and debris orbiting a star 25 light-years from us called Fomalhaut. It is a planet the size of Jupiter orbiting its star at very long distance - 17 billion kilometres.
The studies were published Thursday in Science, a research journal.
"It was completely different discoveries," said Christian Marois of the National Research Council's Herzberg Institute of Astrophysics in Victoria, leader of the three-planet team. "They were made roughly at the same time."
He says "roughly" because finding a planet is never a sudden, one-day discovery.
A dim spot appears in a photo, people stare at it, wonder what it could be, take more pictures, eventually decide it probably isn't a star, and wait for months "to make sure the object is moving with its star. If they move together, that means it's a gravitationally-bound object."
The Hubble, Keck and Gemini telescopes that produced these photos are not new, but Marois said a change in the searching method, rather than new technology, made the breakthrough.
Recently, there's been a trend to looking at bigger stars, hoping they will have more, and bigger, planets. A very large planet isn't easier to see just because of its size, but because it's probably young, hot and probably glowing.
The planets studied by the Marois group may be 500 to 800 Celsius.
As well, the planet around a very big star may orbit at a great distance from it. And being farther from its star makes it easier to see; planets close to a star are lost in the glare.
"We are actually seeing photons, light, from the planet itself. The fact that the system is young, they (planets) are still glowing from a lot of the energy they had accumulated," he said.
Team member Bruce Macintosh of the U.S. Lawrence Livermore National Laboratories adds: "Until now, when astronomers discover new planets around a star, all we see are wiggly lines on a graph of the star's velocity or brightness. Now we have an actual picture showing the planets themselves, and that makes things very interesting."
Photos will show what former detection methods cannot.
Peter Brown of the University of Western Ontario said in an e-mail: "You may get (in principle) a complete orbit, size, mass and possibly a density which allows you to tell things about the planet (is it stony like the Earth or a gas giant?)"
He said photos may also reveal what gases are in the atmosphere.
Meanwhile, Marois added: "The star is in the constellation of Pegasus, so people can get out and see it tonight."
It's a very dim star, barely visible with the naked eye from a very dark location.
Coincidentally, Pegasus is also the constellation where the first planet outside our solar system was discovered (though not seen) back in 1995. It orbits a star called 51 Pegasi.
Marois's group is still studying two other candidates - each one star with a single possible planet - but won't know what's there for certain for several months.
(canada.com)
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