David Kirkpatrick

September 30, 2009

Raining rocks

Filed under: et.al., Science — Tags: , , , — David Kirkpatrick @ 8:33 pm

The universe is an amazing place even in simulation and informed guesswork. Sounds like this planet requires a ultra-duty umbrella.

From the link:

Not so the atmosphere of COROT-7b, an exoplanet discovered last February by the COROT space telescope launched by the French and European space agencies

According to models by scientists at Washington University in St. Louis, COROT-7b’s atmosphere is made up of the ingredients of rocks and when “a front moves in,” pebbles condense out of the air and rain into lakes of molten lava below.

The work, by Laura Schaefer, research assistant in the Planetary Chemistry Laboratory, and Bruce Fegley Jr., Ph.D., professor of earth and planetary sciences in Arts & Sciences, appears in the Oct. 1 issue of The Astrophysical Journal.

Astronomers have found nearly 400 extra-solar planets, or exoplanets, in the past 20 years. But because of the limitations of the indirect means by which they are discovered, most are Hot Jupiters, chubby gas giants orbiting close to their parent stars. (More than 1,300 Earths could be packed inside Jupiter, which has 300 times the mass of Earth.)

COROT-7b, on the other hand, is less than twice the size of Earth and only five times its mass.

It was the first planet found orbiting the star COROT-7, an orange dwarf in the constellation Monoceros, or the Unicorn. (This priority is designated by the letter b.)

November 21, 2008

News from the galaxy

This is some crazy research.

The release:

Crash Test-Iconic Rings and Flares of Galaxies Created by Violent, Intergalactic Collisions, Research by Pitt and Partners Finds

Findings published in “The Astrophysical Journal” challenge existing theory about the formation of such galaxies as the Milky Way

PITTSBURGH-The bright pinwheels and broad star sweeps iconic of disk galaxies such as the Milky Way might all be the shrapnel from massive, violent collisions with other galaxies and galaxy-size chunks of dark matter, according to a multi-institutional project involving the University of Pittsburgh. Published in the Nov. 20 edition of “The Astrophysical Journal,” the findings challenge the longstanding theory that the bright extensions and rings surrounding galaxies are the remnants of smaller star clusters that struck a larger, primary galaxy then fragmented.

The study’s team consisted of Andrew Zentner, a professor of physics and astronomy in Pitt’s School of Arts and Sciences; James Bullock, a physics and astronomy professor at the University of California at Irvine; Stelios Kazantzidis, a postdoctoral researcher at Ohio State University; Andrey Kravtsov, a professor of astronomy and astrophysics at the University of Chicago; and Leonidas Moustakas, a researcher at the NASA Jet Propulsion Laboratory, California Institute of Technology.

The team’s computer simulations of galaxy formation suggests that disk galaxies most likely began as flat, centralized star clusters. Smaller galaxies collided with and tore through these disks billions of years ago, casting disk stars outward into the wild extensions present now; the bright center is the original formation. In addition, vast bodies of dark matter-a low-density, high-gravity invisible mass thought to occupy nearly one-quarter of the Universe-swept through these disks and further pulled stars from the main disk.

The researchers’ scenario largely applies to the formation of the rings and long flares of stars that surround such galaxies as the Milky Way, Zentner said. But the model also presents a possible solution to how star spirals-the arcs of stars that radiate from the center of some disk galaxies-maintain their shape. Spirals form as a result of any disturbance to the star disk, Zentner said. However, the prolonged disturbance of a galaxy and dark matter expanse passing through a disk explains why the spirals seem to never recede.

“Our model suggests that a violent collision throws stars everywhere and continues moving through the disk, disturbing its structure,” Zentner said. “It also has been known for some time that for star spirals to develop and maintain their well-known form, there must be a prolonged disturbance. We show that large masses moving through a galaxy could provide that disturbance.”

The team’s findings were serendipitous, Zentner explained. They were modeling disk galaxies for an unrelated astrological survey when they inadvertently discovered that stars in the main disk scattered when satellite galaxies-smaller galaxies surrounding larger ones-passed through. They shared their results with colleagues a year ago, and the results have since been replicated, Zentner said.

“One of the major advantages of these results is that we didn’t set out to find them,” he said. “They happened as we simulated existing galaxies.”

The paper is available on Pitt’s Web site at http://www.pitt.edu/news2008/zentner_paper.pdf

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Related links:

The Astrophysical Journal