A University of Hawaii astronomer, using the Keck telescopes on Mauna Kea, has captured images of a new planet as it is forming.
What astronomers are calling LkCa 15 b looks like a hot "protoplanet" surrounded by a swath of cooler dust and gas, which is falling into the still-forming planet.
"LkCa 15 b is the youngest planet ever found, about 5 times younger than the previous record holder," said astronomer Adam Kraus of the University of Hawaii’s Institute for Astronomy. "This young gas giant is being built out of the dust and gas. In the past, you couldn’t measure this kind of phenomenon because it’s happening so close to the star. But, for the first time, we’ve been able to directly measure the planet itself as well as the dusty matter around it."
The discovery of LkCa 15 b began as a survey of 150 young dusty stars in star-forming regions. That led to the more concentrated study of a dozen stars.
"LkCa 15 was only our second target, and we immediately knew we were seeing something new," said Kraus. "We could see a faint point source near the star, so thinking it might be a Jupiter-like planet we went back a year later to get more data."
Astronomers used the Keck telescopes’ adaptive optics, which corrects for atmospheric distortions to starlight, and a technique called aperture mask interferometry to capture the images.
The technique, using a small mask with holes in it, allows the astronomers to cancel out the bright light of stars. They can then resolve disks of dust around stars and see gaps in the dusty layers where protoplanets may be hiding.
"It’s like we have an array of small mirrors," said Kraus. "We can manipulate the light and cancel out distortions."
Images have revealed that the forming planet sits inside a wide gap between the young parent star and an outer disk of dust.
"Interferometry has actually been around since the 1800’s, but through the use of adaptive optics has only been able to reach nearby young suns for about the last seven years." said co-discoverer Dr. Michael Ireland, of Macquarie University and the Australian Astronomical Observatory. "Since then we’ve been trying to push the technique to its limits using the biggest telescopes in the world, especially Keck."
Kraus presented the discovery at a meeting at NASA’s Goddard Space Flight Center today. The meeting follows the acceptance of a research paper on the discovery by Kraus and Ireland, in The Astrophysical Journal (available at http://arxiv.org/abs/1110.3808)