Ancient 'Methuselah star' Just Got Younger, Hubble Helps Astronomers Correct Age
Astronomers using NASA's Hubble Space Telescope recently found that a star appeared to be older than the Universe, according to NASA. Researchers say that some factors that weren't considered earlier could decrease the estimated age of the star.
"We have found that this is the oldest known star with a well-determined age," said Howard Bond of Pennsylvania State University in University Park, Pa., and the Space Telescope Science Institute in Baltimore, Md, in a news release from NASA.
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Previous study on the star, back in 2000, had estimated the star's age to be around 16 billion years.
The age of the "Methuselah star", cataloged as HD 140283, is expected be around 14.5 billion years, give or take 800 million years. However, what is surprising is that most astronomers accept that the Universe is about 13.8 billion years old.
"Maybe the cosmology is wrong, stellar physics is wrong, or the star's distance is wrong. So we set out to refine the distance," Bond said.
According to NASA, the star may have formed during the early years of the Universe, when the Universe had many heavy elements. The star is currently at the first stage of expanding into a red giant. Researchers calculate the distance to the star as 190.1 light-years and the star is currently zooming past the solar system at the speed of 800,000 miles per hour.
The distance to the star was measured by Bond and colleagues using trigonometric parallax, in which distance between stars is measured by observing apparent shift of the star relative to an observer.
Another indicator that may lower the star's age further is the oxygen-to-iron ratio that's greater than predictor. This ratio reduces as a star ages. According to Bond, measuring the oxygen level in the star will lead to a better understanding of the star's age. The star probably came into existence when the Universe was abundant in oxygen, making the star younger than estimated.
"Put all of those ingredients together and you get an age of 14.5 billion years, with a residual uncertainty that makes the star's age compatible with the age of the universe. This is the best star in the sky to do precision age calculations by virtue of its closeness and brightness," said Bond.
The study is published in the journal called Astrophysical Journal Letters.