New Planets Found

TECHNOLOGY - Christian Marois, a young astrophysicist with Canada's National Research Council, was on a plane over the Pacific, poring over telescopic images of the star HR 8799 - an unremarkable pinprick in the Pegasus constellation - when he noticed two planets circling the star.

"It was the first image of another planet system orbiting another star," says Marois, who is just completing a post-doctoral stint at the council's Herzberg Institute of Astrophysics in Victoria.

His find would later turn out to be three planets.

Circling HR 8799, 128 light years (128 X 9.46 trillion kilometres) from Earth, the planetary trio are between seven and 10 times the mass of Jupiter.

Some 50 per cent more massive and five times more luminous than our sun, HR 8799 is visible to the naked eye, if you just look towards Pegasus near its zenith in the northern latitudes.

Some 300 planets have been detected around distant stars over the past 10 years, but these orbiting bodies have been inferred, rather than photographed, largely by the "wobble" they create in their stars as they pull it gravitationally in different directions during their circling orbits. This is the first time planets have been photographed and proven to be there.

There has been "exoplanet" sightings reported in the literature - another is reported in this same Science edition - Marois says his images are the clearest and definitely the first to show a distant solar system.

"We had to look at a lot of stars in order to be able to see these," says Marois, whose planetary quest began eight years ago.

Because stars are often 25 times brighter than their planets -- which simply mirror the starlight - they typically drown out any of the planetary glow that might be glimpsed by earthbound lenses. Marois says 80 stars, painstakingly pared down from the billions available, were scrutinized before the HR 8799 planets appeared.

The HR 8799 solar system is only about 60 million years old, compared to the 4.6 billion years that our planetary neighbourhood has been around.

And the trio of planets are between 5.3 and 6.6 times hotter than Jupiter.

As important as meeting these stellar criteria, Marois needed a new way to observe the skies that would separate the brighness of the stars from the puny, planetary glow.

That problem was solved by a software program he himself developed as a PhD. candidate at the University of Montreal, which allowed planetary bodies to come out from their sun's bright shadow far more readily than ever before.

"The new observing strategy that I developed ...enabled us extract very well the light from the star by a factor of 10 to 100, so these were the deepest images ever obtained on any telescope," he says

Marois says these earthbound telescopes, with their 10 metre apertures, are actually better than the space based Hubble telescope at planet detection (for a variety of reasons). Indeed the Hubble already eyes HR 8799 in the 1990s and failed to reveal its planets.

As gas giants far more massive that our behemoth Jupiter, the planets have virtually no capacity to support life, but that doesn't mean we won't find a nice blue planet in the future capable of supporting life.

And if we ever develop the technology for really detailed photos, what else might we see on those planets or circling those planets? Evidently satellites would suggest a technologically advanced culture.

Someday, perhaps sooner than we think.