Christopher W. Purcell, postdoctoral research associate in the Department of Physics and Astronomy in Pitt's School of Arts and Sciences, and his colleagues have reported their observations in a paper, on September 15. They have reported that the spirality is a result of the impact of Sagittarius Dwarf during the early stages of the universe.
Supercomputers are generally used by the astrophysicists to produce a small scale simulation of what might have happened to the particular body in it's earlier stages of life. Then they would speed up the time and observed the simulated model to make further predictions of what might have happened during the course of it's life. Finally the results will be tested, observing the present universe. I hope now you understood what these simulations have got to do in our present context.
In the simulations, Purcell ended up finding two interesting things. One about the stars of the Sagittarius dwarf and other about the dark matter present in the dwarf. Our earlier observations using infrared telescopes in 2003 reported that the Dwarf had collided with the Milky-way twice as of date. Purcell says that theirs is the first ever to find out the effects of this impact on our galaxy.
Purcell says, "When all the dark matter smacked into the Milky Way, 80 to 90 percent of it was stripped off,". He added that this was when the first impact took place. He explains the spirality of the arms of Milky-way galaxy as follows: our galaxy rotates faster towards its center than towards it's edges. As a result, the instabilities were stretched and ended up forming spiral arms. The simulations conclude that by the time the second impact took place, the dwarf had completely lost it's dark matter and thus leaving free all the stars in it which then were pulled apart by the Milky-way's gravitational force.
Interesting thing about this whole story is the researches found out that the galaxy will be subjected to another impact by the next 10 million years. When asked about this Purcell said, "Immediately on the opposite side of us, we can see this blob of stars crashing into the southern face of the disc from beneath. We can measure the velocities of these stars. We know that the dwarf galaxy is just about to smash the disc—in only another 10 million years.". Lol you might be laughing after listening the left over time but let me tell you, the thing here is how appreciable the works are !! Congrats to the team and stay glued, more news about this yet to come .
Ref: eurekalert
September 15, 2011.
Pranu :-)
In the simulations, Purcell ended up finding two interesting things. One about the stars of the Sagittarius dwarf and other about the dark matter present in the dwarf. Our earlier observations using infrared telescopes in 2003 reported that the Dwarf had collided with the Milky-way twice as of date. Purcell says that theirs is the first ever to find out the effects of this impact on our galaxy.
Purcell says, "When all the dark matter smacked into the Milky Way, 80 to 90 percent of it was stripped off,". He added that this was when the first impact took place. He explains the spirality of the arms of Milky-way galaxy as follows: our galaxy rotates faster towards its center than towards it's edges. As a result, the instabilities were stretched and ended up forming spiral arms. The simulations conclude that by the time the second impact took place, the dwarf had completely lost it's dark matter and thus leaving free all the stars in it which then were pulled apart by the Milky-way's gravitational force.
Interesting thing about this whole story is the researches found out that the galaxy will be subjected to another impact by the next 10 million years. When asked about this Purcell said, "Immediately on the opposite side of us, we can see this blob of stars crashing into the southern face of the disc from beneath. We can measure the velocities of these stars. We know that the dwarf galaxy is just about to smash the disc—in only another 10 million years.". Lol you might be laughing after listening the left over time but let me tell you, the thing here is how appreciable the works are !! Congrats to the team and stay glued, more news about this yet to come .
Ref: eurekalert
September 15, 2011.
Pranu :-)
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