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Author Topic:   See-Through Galaxies
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Joined: 03-14-2004

Message 1 of 2 (842591)
11-03-2018 8:18 AM

Defying Theories, This Ghostly Galaxy Has Almost No Dark Matter
A unique galaxy is making the case for dark matter, even though it has very little of the mysterious substance. Astronomers have determined that the galaxy NGC 1052-DF2, or DF2 for short, has 400 times less dark matter than expected for an object of its size.
In addition to providing insight into how galaxies form, the unusual galaxy is helping strengthen the argument for the existence of dark matter, researchers said.
According to the new paper's lead author, Pieter van Dokkum, a researcher from Yale University, the galactic find challenges the standard idea of how galaxies are born. While interactions between normal and dark matter have long been considered a key element in galaxy formation, the dearth of dark matter in this galaxy challenges that assumption.
"Dark matter is apparently not a requirement for forming a galaxy," van Dokkum told by email.
Finding anomalies is how science progresses -- if something doesn't fit the current model then the model needs modification or we need a new model.
Also, making our galaxy see-through:
See-through Galaxy: Revealing The Milky Way's Center
San Diego, CA -- The center of our galaxy is hidden behind a "brick wall" of obscuring dust so thick that not even the Hubble Space Telescope can penetrate it. Astronomers Silas Laycock and Josh Grindlay (Harvard-Smithsonian Center for Astrophysics) and colleagues have lifted that veil to reveal a beautiful vista swarming with stars. Moreover, their hunt for specific stars associated with X-ray-emitting sources has ruled out one of two options for the nature of these X-ray sources: most apparently are not associated with massive stars, which would have shown up as bright counterparts in their deep infrared images. This points to the X-ray sources being white dwarfs, not black holes or neutron stars, accreting matter from low-mass binary companion stars.
To peer into the galactic center, Laycock and Grindlay used the unique capabilities of the 6.5-meter-diameter Magellan Telescope in Chile. By gathering infrared light that more easily penetrates dust, the astronomers were able to detect thousands of stars that otherwise would have remained hidden. Their goal was to identify stars that orbit, and feed, X-ray-emitting white dwarfs, neutron stars or black holes - any of which could yield the faint X-ray sources discovered originally with NASA's Chandra X-ray Observatory.
Science also advances by ruling out possibilities for the source of x-ray emitting stars.

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