agribusiness: Spliced feed for The Science Network

Thursday, July 17, 2008

Spliced feed for The Science Network

Active galactic nuclei with laser guide star adaptive optics [Excited Light]

Posted: 16 Jul 2008 10:10 AM CDT

I found this presentation on Google Video: Active galactic nuclei with laser guide star adaptive optics. It is from the AAS 212th Meeting. The presenter is Claire Max.

Adaptive optics on the current generation of 8 - 10 meter telescopes yields spatial resolutions in the near-infrared comparable to those of Hubble at visible wavelengths. Laser guide stars are now making these high spatial resolutions available over a large fraction of the sky. I will describe several areas in which these advances are being applied to AGN science: 1) measurement of black hole masses in nearby galaxies from kinematics of stars and gas; 2) study of the spatial distribution of stellar populations and dust in galaxies at 0.5 < z < 1.5, and 3) tests of the relationship between galaxy mergers and AGN activity. I will conclude with a discussion of the planned Next Generation Adaptive Optics system at the W. M. Keck Observatory, outlining the expected improvements in AGN science with this new system.

A timelapse of the Paranal laser guide star [Excited Light]

Posted: 16 Jul 2008 09:54 AM CDT

The authors of the time lapse movie are Stéphane Guisard, Valère Leroy and Jean Pajus. It is fun to see the PARSEC laser pointing to different directions of the universe over the night. I wonder what the night sky would look like in Hawaii, where there are several guide star lasers.

This is a time lapse movie made from individual images taken with a Canon 20Da camera and a 8mm lens. This accelerated movie shows a complete night at Paranal Observatory starting at sunset and finishing at dawn. That night, the Laser Guide Star Facility was in use and its yellow sodium Laser beam left its footprint on our movie. The laser beam creates a Laser Guide Star in the high atmosphere, 90 km above us. This ‘bright’ artificial star helps the adaptive optics system located in the main telescope, to measure and correct the distorsions of the images produced by the atmosphere, in real time and several hundreds of times per second.

The bright part of the Milky Way, containing the galactic center, is disappearing to the west on the left hand side of the movie. The Andromeda galaxy is visible also, as a diffused and elongated spot crossing the sky just above the domes. One can also see the Pleiades and “upside down” Orion constellation rising (remember this movie is done from the Southern hemisphere) together with the other half of our Milky Way . Finally the moon lightens the morning sky just before sunrise.

Saturn recycles its rings, creates new ones [Earth & Sky Podcast]

Posted: 16 Jul 2008 04:07 AM CDT

In the 1970s, Voyager 1 provided the first close-up views of Saturn's rings, and determined that the rings formed about 100 million years ago. But evidence from the more recent Cassini mission suggests the rings are much older.