http://www.astronomy.com/news/2014/02/hubble-watches-stars-clockwork-motion-in-nearby-galaxy
Using the sharp-eyed NASA Hubble Space Telescope, astronomers have for the first time precisely measured the rotation rate of a galaxy based on the clock-like movement of its stars.
According to their analysis, the central part of the neighboring galaxy, called the Large Magellanic Cloud (LMC), completes a rotation every 250 million years. It takes our Sun the same amount of time to complete a rotation around the center of our Milky Way Galaxy.
The Hubble team — Roeland van der Marel of the Space Telescope Science Institute in Baltimore, Maryland, and Nitya Kallivayalil of the University of Virginia in Charlottesville, Virginia — used Hubble to measure the average motion of hundreds of individual stars in the LMC, located 170,000 light-years away. Hubble recorded the stars' slight movements during a seven-year period.
"Studying this nearby galaxy by tracking the stars' movements gives us a better understanding of the internal structure of disk galaxies," said Kallivayalil. "Knowing a galaxy's rotation rate offers insight into how a galaxy formed, and it can be used to calculate its mass."
Disk-shaped galaxies such as the Milky Way and the LMC generally rotate like a carousel. Hubble's precision tracking offers a new way to determine a galaxy's rotation by the "sideways" proper motion of its stars, as seen in the plane of the sky. Astronomers have long measured the sideways motions of nearby celestial objects, but this is the first time the precision has become sufficient to see another distant galaxy rotate.
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Using the sharp-eyed NASA Hubble Space Telescope, astronomers have for the first time precisely measured the rotation rate of a galaxy based on the clock-like movement of its stars.
According to their analysis, the central part of the neighboring galaxy, called the Large Magellanic Cloud (LMC), completes a rotation every 250 million years. It takes our Sun the same amount of time to complete a rotation around the center of our Milky Way Galaxy.
The Hubble team — Roeland van der Marel of the Space Telescope Science Institute in Baltimore, Maryland, and Nitya Kallivayalil of the University of Virginia in Charlottesville, Virginia — used Hubble to measure the average motion of hundreds of individual stars in the LMC, located 170,000 light-years away. Hubble recorded the stars' slight movements during a seven-year period.
"Studying this nearby galaxy by tracking the stars' movements gives us a better understanding of the internal structure of disk galaxies," said Kallivayalil. "Knowing a galaxy's rotation rate offers insight into how a galaxy formed, and it can be used to calculate its mass."
Disk-shaped galaxies such as the Milky Way and the LMC generally rotate like a carousel. Hubble's precision tracking offers a new way to determine a galaxy's rotation by the "sideways" proper motion of its stars, as seen in the plane of the sky. Astronomers have long measured the sideways motions of nearby celestial objects, but this is the first time the precision has become sufficient to see another distant galaxy rotate.
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