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Science/Tech See other Science/Tech Articles Title: How Can a Star Be Older Than the Universe? Space Mysteries: If the universe is 13.8 billion years old, how can a star be more than 14 billion years old? This Digitized Sky Survey image shows the oldest star with a well-determined age in our galaxy. Called the Methuselah star, HD 140283 is 190.1 light-years away. Astronomers refined the star's age to about 14.5 billion years (which is older than the universe), plus or minus 800 million years. Image released March 7, 2013. This Digitized Sky Survey image shows the oldest star with a well-determined age in our galaxy. Called the Methuselah star, HD 140283 is 190.1 light-years away. Astronomers refined the star's age to about 14.3 billion years (which is older than the universe), plus or minus 800 million years. Image released March 7, 2013. (Image: © Digitized Sky Survey (DSS), STScI/AURA, Palomar/Caltech, and UKSTU/AAO) For more than 100 years, astronomers have been observing a curious star located some 190 light years away from Earth in the constellation Libra. It rapidly journeys across the sky at 800,000 mph (1.3 million kilometers per hour). But more interesting than that, HD 140283 — or Methuselah as it's commonly known — is also one of the universe's oldest known stars. In 2000, scientists sought to date the star using observations via the European Space Agency's (ESA) Hipparcos satellite, which estimated an age of 16 billion years old. Such a figure was rather mind-blowing and also pretty baffling. As astronomer Howard Bond of Pennsylvania State University pointed out, the age of the universe — determined from observations of the cosmic microwave background — is 13.8 billion years old. "It was a serious discrepancy," he said. Related: The Methuselah Star: Oldest Known Star Revealed (Gallery) Taken at face value, the star's predicted age raised a major problem. How could a star be older than the universe? Or, conversely, how could the universe be younger? It was certainly clear that Methuselah — named in reference to a biblical patriarch who is said to have died aged 969, making him the longest lived of all the figures in the Bible — was old, since the metal-poor subgiant is predominantly made of hydrogen and helium and contains very little iron. It's composition meant the star must have come into being before iron became commonplace. But more than two billion years older than its environment? Surely that is just not possible. Click here for more Space.com videos... CLOSE Taking a closer look at the age of Methuselah Bond and his colleagues set themselves to the task of figuring out whether or not that initial figure of 16 billion was accurate. They pored over 11 sets of observations that had been recorded between 2003 and 2011 by the Fine Guidance Sensors of the Hubble Space Telescope, which make a note of the positions, distances and energy output of stars. In acquiring parallax, spectroscopy and photometry measurements, a better sense of age could be determined. "One of the uncertainties with the age of HD 140283 was the precise distance of the star," Bond told All About Space. "It was important to get this right because we can better determine its luminosity, and from that its age — the brighter the intrinsic luminosity, the younger the star. We were looking for the parallax effect, which meant we were viewing the star six months apart to look for the shift in its position due to the orbital motion of the Earth, which tells us the distance." There were also uncertainties in the theoretical modelling of the stars, such as the exact rates of nuclear reactions in the core and the importance of elements diffusing downwards in the outer layers, he said. They worked on the idea that leftover helium diffuses deeper into the core, leaving less hydrogen to burn via nuclear fusion. With fuel used faster, the age is lowered. Post Comment Private Reply Ignore Thread
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