Post by clone on Feb 26, 2012 17:53:31 GMT -8
This same sense of shock came as scientists announced that the Sun, the Moon, our planet and its siblings, were not born into the familiar band of stars known as the Milky Way galaxy, but we actually belong to a strange formation with the unfamiliar name of the Sagittarius Dwarf galaxy!
How can this be?
Using volumes of data from the Two-Micron All Sky Survey (2MASS), a major project to survey the sky in infrared light led by the University of Massachusetts, the astronomers are answering questions that have baffled scientists for decades and proving that our own Milky Way is consuming one of its neighbors in a dramatic display of ongoing galactic cannibalism. The study published in the Astrophysical Journal, is the first to map the full extent of the Sagittarius galaxy and show in visually vivid detail how its debris wraps around and passes through our Milky Way. Sagittarius is 10,000 times smaller in mass than the Milky Way, so it is getting stretched out, torn apart and gobbled up by the bigger Milky Way.
The fact that the Milky Way is seen in the sky at an angle has always puzzled astronomers. If we originated from the Milky Way, we ought to be oriented to the galaxy's ecliptic, with the planets aligned around our Sun in much the same angle as our Sun aligns with the Milky Way. Instead, as first suggested by researcher Matthew Perkins Erwin, the odd angle suggests that our Sun is influenced by some other system. Together with data from the Two-Micron All Sky Survey we now know what it is. We actually belong to the Sagittarius Dwarf galaxy.
Earth from Sagittarius Dwarf, not Milky Way?
Bad Astronomy blogs.discovermagazine.com/badastronomy/ spends a fair bit of time debunking the claim blogs.discovermagazine.com/badastronomy/2007/06/27/is-the-sun-from-another-galaxy/ that our solar system is from Sagittarius Dwarf:
I talked to Steve Majewski, the lead author on the horribly maligned scientific paper about the Sagittarius Dwarf galaxy. He thanks me for saving him the trouble of having to debunk the claim himself. :-) He has updated his original page www.astro.virginia.edu/~mfs4n/sgr/ about all this with a disclaimer saying the Viewzone article is wrong, too.
This image, and its associated movie, shows the distribution of stars in the shredded Sagittarius dwarf galaxy as revealed by the observations reported here. The image is based on the best model match to the map of 2MASS M-giant stars. The thin flat blue spiral represents the disk of our Milky Way galaxy (the shape and size of this disk is not derived as part of this work). The yellow dot represents the position of the Sun. Sagittarius debris can be seen extending from the dense 'core' of the Sagittarius dwarf, wrapping around the galaxy, and descending through the Sun's position. Click on the image to obtain an MPEG movie showing a 3-D 'flyaround' view of Sagittarius' current predicament. Credit David Law/University of Virginia
This image, and its associated movie, is illustrative of work by other astronomers, Kathryn Johnston of Wesleyan University in this case, to simulate the evolution of the interactions of dwarf galaxies like Sagittarius with the Milky Way through time. The animation, obtained by clicking on the image, begins when a Sagittarius-like dwarf galaxy was a compact, largely undisturbed system, and follows the Milky Way's disruptive influence over time as the dwarf orbits the Milky Way. If this were the Sagittarius system, this simulation would span approximately 2 billion years in the past through 500 million years into the future. Credit Kathryn Johnston/Wesleyan University.