View Full Version : Two new papers on planet formation

2011-Oct-21, 01:42 PM
Both of these are from R&D magazine on-line

First - on spiral arms (http://www.rdmag.com/News/2011/10/General-Science-Space-Spiral-Arms-Hint-At-The-Presence-Of-Planets/?et_cid=2262613&et_rid=54734303&linkid=http%3a%2f%2fwww.rdmag.com%2fNews%2f2011%2f 10%2fGeneral-Science-Space-Spiral-Arms-Hint-At-The-Presence-Of-Planets%2f)

A new image of the disk of gas and dust around a sun-like star has spiral-arm-like structures. These features may provide clues to the presence of embedded but as-yet-unseen planets.

"Detailed computer simulations have shown us that the gravitational pull of a planet inside a circumstellar disk can perturb gas and dust, creating spiral arms. Now, for the first time, we're seeing these features," says Carol Grady, a National Science Foundation (NSF)-supported astronomer with Eureka Scientific Inc.

The newly imaged disk surrounds SAO 206462, a star located about 456 light-years away in the constellation Lupus. Astronomers estimate that the system is only about 9 million years old. The gas-rich disk spans some 14 billion miles, which is more than twice the size of Pluto's orbit in our own solar system.

"The surprise," says Grady, "was that we caught a glimpse of this stage of planet formation. This is a relatively short-lived phase."

A near-infrared image from the National Astronomical Observatory of Japan shows a pair of spiral features arcing along the outer disk. Theoretical models show that a single embedded planet may produce a spiral arm on each side of a disk. The structures around SAO 206462 do not form a matched pair, suggesting the presence of two unseen worlds, one for each arm. However, the research team cautions that processes unrelated to planets may also give rise to these structures.

Second - on image capture (http://www.rdmag.com/News/2011/10/General-Science-Astrophysics-Imaging-Hawaii-astronomer-captures-image-of-forming-planet/)

Astronomers have captured the first direct image of a planet being born.

Adam Kraus, of the University of Hawaii's Institute for Astronomy, said the planet is being formed out of dust and gas circling a 2-million-year-old star about 450 light years from Earth.

The planet itself, based on scientific models of how planets form, is estimated to have started taking shape about 50,000 to 100,000 years ago.

Called LkCa 15 b, it's the youngest planet ever observed. The previous record holder was about five times older.

Kraus and his colleague, Michael Ireland from Macquarie University and the Australian Astronomical Observatory, used Keck telescopes on Mauna Kea to find the planet.

"We're catching this object at the perfect time. We see this young star, it has a disc around it that planets are probably forming out of and we see something right in the middle of a gap in the disc," Kraus said in a telephone interview.

Kraus presented the discovery Wednesday at NASA's Goddard Space Flight Center in Maryland. Kraus and Ireland's research paper on the discovery is due to appear in The Astrophysical Journal.

The first article has the actual image they took; unfortunately, the second does not (maybe because the paper is yet to be published).

2011-Oct-21, 06:55 PM
The Guardian (http://www.guardian.co.uk/science/2011/oct/20/youngest-planet-ever-found-lkca15b) also has a story about the work on LkCa 15 b, and their story includes the actual image.

John Jaksich
2011-Oct-22, 01:22 AM
The Guardian (http://www.guardian.co.uk/science/2011/oct/20/youngest-planet-ever-found-lkca15b) also has a story about the work on LkCa 15 b, and their story includes the actual image.

I thought that the paper seemed familiar to me --I have noticed LkCa15 b at the e-print archive yesterday

Please don't bot the link

here it is: