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October 19, 2011
Ms. Louise Good
Dr. Adam Kraus
Dr. Michael Ireland
|Artist’s conception of the area near the planet LkCa 15 b. Click on picture for larger view. Credit: Karen L. Teramura, UH IfA.|
The first direct image of a planet in the process of forming around its star has been captured by University of Hawaii astronomer Adam Kraus.
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. Images have revealed that the forming planet sits inside a wide gap between the young parent star and an outer disk of dust.
Kraus (UH Institute for Astronomy) and colleague Michael Ireland (Macquarie University and the Australian Astronomical Observatory) combined the power of the 10-meter Keck telescopes with a bit of optical sleight of hand.
"LkCa 15 b is the youngest planet ever found, about 5 times younger than the previous record holder," said Kraus. "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."
Kraus will be presenting the discovery at an Oct. 19 meeting at NASA's Goddard Space Flight Center. The meeting follows the acceptance of a research paper on the discovery by Kraus and Ireland by The Astrophysical Journal.
The optical sleight of hand used by the astronomers is to combine the power of Keck's Adaptive Optics with a technique called aperture mask interferometry. The former is the use of a deformable mirror to rapidly correct for atmospheric distortions of starlight. The latter involves placing a small mask with several holes in the path of the light collected and concentrated by a giant telescope. With that, the scientists can manipulate the light waves.
"It's like we have an array of small mirrors," said Kraus. "We can manipulate the light and cancel out distortions." The technique 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.
"Interferometry has actually been around since the 1800s, but through the use of adaptive optics has only been able to reach nearby young suns for about the last 7 years." said Dr. Ireland. "Since then we've been trying to push the technique to its limits using the biggest telescopes in the world, especially Keck."
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."
In further investigations at varying wavelengths, the astronomers were intrigued to discover that the phenomenon was more complex than a single companion object.
"We realized we had uncovered a super Jupiter-sized gas planet, but that we could also measure the dust and gas surrounding it. We'd found a planet at its very beginning" said Kraus.
Drs. Kraus and Ireland plan to continue their observations of LkCa 15 and other nearby young stars in their efforts to construct a clearer picture of how planets and solar systems form.
The paper is available at http://arxiv.org/abs/1110.3808.
The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth's turbulent atmosphere. The Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.
Founded in 1967, the Institute for Astronomy at the University of Hawaii at Manoa conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea.
Established in 1907 and fully accredited by the Western Association of Schools and Colleges, the University of Hawaii is the state's sole public system of higher education. The UH System provides an array of undergraduate, graduate, and professional degrees and community programs on 10 campuses and through educational, training, and research centers across the state. UH enrolls more than 50,000 students from Hawaii, the U.S. mainland, and around the world.