Harvard-Smithsonian Astronomers Reveal New 3-D Map of Universe
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In this projection, the plane of the Milky Way runs horizontally across the center of the image. Credit: T.H. Jarrett (IPAC/SSC)
With one of my very first Astronomy research projects being based on the 2MASS data, I have a bit of a personal connection to this announcement by the team at the Harvard-Smithsonian Center for Astrophysics. I never cease to be amazed by scientific findings that are made years, and even decades after the initial data is acquired.
The 2MASS Redshift Survey, which took more than ten years to complete, produced the most complete 3-D map of the local universe (out to a distance of 380 million light-years) yet. This new map was presented this week at the 218th meeting of the American Astronomical Society.
“The 2MASS Redshift Survey is a wonderfully complete new look at the local universe – particularly near the Galactic plane,” Masters said. “We’re also honoring the legacy of the late John Huchra, an astronomer at the Harvard-Smithsonian Center for Astrophysics, who was a guiding force behind this and earlier galaxy redshift surveys.”
To generate a 3-D map, the researchers utilized redshift measurements to calculate galaxy distances, which provide a third dimension to the map. The researchers chose galaxies made by the Two-Micron All-SkySurvey (2MASS). Utilizing three “near-infrared” wavelengths, 2MASS was able to see through obscuring dust that ordinarily blocks visible light. The end result is a sky survey that is generally more complete than what would be available with standard optical telescopes.
The concept of redshift is essential to measuring distances between galaxies. The light from a galaxy is redshifted, (longer wavelengths), as a result of cosmic expansion. Galaxies that are more distant have a greater redshift, and as such, the redshift data can be used to calculate galactic distances.
Huchra began measuring redshifts for galaxies that did not have previously established redshift data in the late 1990s, primarily using a telescope at the Fred Lawrence Whipple Observatory on Mt. Hopkins, AZ, and one at the Cerro Tololo Inter-American Observatory in Chile. Shortly after Huchra’s death in October 2010, 2MRS researchers performed the last of the observations necessary to complete the survey.
Robert Kirshner, a colleague of Huchra’s at the Center for Astrophysics, mentions, “John loved doing redshift surveys and he loved the infrared. He had the insight to tell when infrared technology, formerly the province of the experts, was ripe for routine use in a big project.” Kirshner adds, “John was instrumental in setting up the 2MASS telescope at Mount Hopkins, seeing the infrared side of the project through, and making a much more complete survey of the local universe. It’s a wonderful tribute to John that his colleagues have finished the infrared-selected galaxy redshift survey that John started”.
The new survey studied areas that were previously hidden in the Milky Way galaxy in order to better understand how those areas affect the galaxy’s motion. Researchers have been trying to better understand the motion of the Milky Way with respect to the rest of the universe, since previously the motion couldn’t be explained by the gravitational attraction from any visible matter. Large structures in our galaxy, such as the Hydra-Centaurus region (the “Great Attractor”) were previously unviewable, but are now visible by 2MRS.
Headquartered in Massachusetts, the Harvard-Smithsonian Center for Astrophysics is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory where scientists study the origin, evolution and ultimate fate of the universe.
Source:Harvard-Smithsonian Center for Astrophysics Press Release
Ray Sanders is a Sci-Fi geek, astronomer and blogger. Currently researching variable stars at Arizona State University, he writes for Universe Today, The Planetary Society blog, and his own blog, Dear Astronomer
2012-12-04 08:06:06
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