Tuesday, January 31, 2017
Scientists trained the Hubble Space Telescope view of the galaxy UGC 9391, which contains variable stars and supernovas that scientists studied to calculate a newly precise value for Hubble's constant. What they found was the universe expanding 5 to 9 percent faster than astronomers had thought.
Scientists used NASA's Hubble Space Telescope to study 2,400 Cepheid stars and 300 Type Ia supernovas.
These are two different universe phenomenon allow scientists to measure distances across the universe. Cepheids pulse at predictable rates and Type Ia supernovas blaze up with consistent luminosity. This allowed the distances to the 300 supernovas, which lie in a number of different galaxies. Then, the researchers compared these figures to the expansion of space, which was calculated by measuring how light from faraway galaxies stretches as it moves away from Earth, to determine how fast the universe is expanding — a value known as the Hubble constant.
The new value for the Hubble constant comes out to 45.5 miles per second per megaparsec. (One megaparsec is equivalent to 3.26 million light-years.)
The new figure is 5 to 9 percent higher than previous estimates of the Hubble constant, which relied on measurements of the cosmic microwave background radiation which is an "echo" of the universe's creation 13.8 billion years ago.
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