January 11, 2005First exoplanet imaged by Hubble?
Astronomers using the Hubble Space Telescope's NICMOS infrared camera think they may have made the first direct image of an extrasolar planet. The candidate object lies close to a young brown dwarf star 225 light-years away in the southern constellation Hydra. While the astronomers think the object is a planet, they are not yet certain the object is actually orbiting the brown dwarf.
In April 2004, another team of astronomers at the Very Large Telescope (VLT) in Chile detected a possible planet
around the brown dwarf, 2MASSWJ 1207334-393254 (or 2M1207 for short). But they could not confirm it. The candidate planet shines with only 1 percent of the brown dwarf's brightness, and it has a temperature of some 1,250 kelvins (1,800° Fahrenheit) — cooler than a lightbulb filament.
Glenn Schneider of the University of Arizona led the team using Hubble to study the object. Comparing the object's VLT location in the sky with that determined by Hubble, Schneider says, "The NICMOS position measurements, relative to the VLT's, indicate the object is a true, orbiting companion." He rates the chance of the object not being a planet at only 1 percent.
If this proves to be a planet, says Schneider, "it has about 5 times the mass of Jupiter." And it orbits at a distance of 54 astronomical units from the star, he says. One "year" would last some 2,500 Earth years.
The brown dwarf star belongs to a group of young stars called the TY Hydrae association that were all born around the same time. No member of the association is believed to be more than 8 to 10 million years old.
Schneider plans follow-up observations with NICMOS on Hubble April 2005.