Using the Hubble Space Telescope earlier this month, the astronomers found no other brown dwarfs orbiting 1 billion miles or more from the star, but they cannot rule out the possibility of planets the size of Jupiter or smaller orbiting the star. Astronomers have been trying to spot brown dwarfs for more than 20 years. Their lack of success is partly due to the fact that as brown dwarfs age, they become cooler, fainter, and more difficult to see. Caltech's Nakajima reasoned that, although brown dwarfs of that age would be much fainter than any known star, they would still be bright enough to be spotted. With the advent of sophisticated light sensors and adaptive optics, astronomers now have the powerful tools they need to resolve smaller and dimmer objects near stars.
Stars appear to twinkle as starlight passes through shifting air pockets that act as roving lenses.
The Hopkins-built device uses a computer to precisely measure the twinkle of starlight. Then a small mirror compensates for the distortion by rapidly tilting and tipping, undoing much of the atmosphere's distorting effect. As a result, the contrast between the images of the faint brown dwarf and its brighter stellar companion was improved. The astronomers then used the coronagraph, which blocks much of the star's glare with an opaque disk, to more easily see the faint brown dwarf orbiting its far brighter companion. Also involved in designing and building the Adaptive Optics Coronagraph were Johns Hopkins engineer Robert Barkhouser and Mark Clampin, a former Hopkins scientist who is now affiliated with the Space Telescope Science Institute in Baltimore.