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06-08-12, 05:34 PM
TA-DA! http://milkyway.cs.rpi.edu/download/plots/lb_polar_sgr.png This is a preliminary image from a research paper that we are currently putting together. It uses data from Milkyway@home's separation application! What you are looking at is a map of the Sagittarius Tidal Debris Stream, as seen by looking "up" out of the disk of our galaxy. The coordinates are in "Galactic Latitude (l) and Longitude (b)" - "l" runs along the disk of the galaxy, with 0 degrees as the line from the Sun to the galactic center, and "b" is the angle above the plane. (It's just like Latitude and Longitude on Earth, but with the Sun t the center and on a galactic scale). The colors represent the square root of the number of stars (it will be the actual number in the final plot). A summary of (l,b) can be found here (http://en.wikipedia.org/wiki/Galactic_coordinate_system). What we've done ("we" including all of you here at Milkyway@home) is fit our statistical model to the Sloan Digital Sky Survey star data, and then using the Separation code, we removed the Sagittarius Tidal Stream from the background of Milky Way galaxy stars. The Sagittarius Tidal Stream is part of the Sagittarius Dwarf galaxy, which is currently "falling into" the Milky Way galaxy. As it falls into the Milky Way, tidal forces (http://en.wikipedia.org/wiki/Tidal_forces) stretch out the loose stars in a massive stream stretching all the way around the galaxy. Over time, these stars will eventually merge with the other Milky Way stars - We are "gobbling up" the Sagittarius Dwarf! In fact, many of the outer stars in our galaxy may have been "cannibalized" from other galaxies in this way! This map will help us understand the distribution of mass (*ahem* Dark Matter) in our galaxy, as well as provide insight into the formation history of galaxies in general. I'll post up a link to the paper as soon as we submit it to the reviewers! (Sorry that I've been away for awhile - I recently recovered from a head injury that kept me out for a month, and I'm finally feeling back up to full strength!)
More... (http://milkyway.cs.rpi.edu/milkyway/forum_thread.php?id=2923)
More... (http://milkyway.cs.rpi.edu/milkyway/forum_thread.php?id=2923)