For over 100 years, astronomers have observed a curious star located about 190 light-years from Earth in the constellation Libra. Fast travels through the sky at 800,000 miles per hour (1.3 million miles per hour). But more interesting than that is that HD 140283 – or Methuselah, as it is known – is also one of the oldest known stars in the universe.
In 2000, scientists tried to date the star through observations through the satellite of the European Space Agency (ESA) Hyparkos, which estimated the age of 16 billion years. Such a figure was quite mind-blowing and also quite puzzling. As the astronomer Howard Bond of Pennsylvania State University pointed out, the age of the universe ̵
1; as determined by observations from the cosmic microwave background – is 13.8 billion years old. "It was a serious discrepancy," he said.
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Taken at face value, the estimated age of the star raised a Major Problem. How can a star be older than the universe? Or, conversely, how can the universe be younger? It was certainly clear that Methuselah – named in connection with a biblical patriarch who was said to have died at the age of 969, which made him the longest lived of all figures in the Bible – was old because he was growing up with It is mainly made of hydrogen and helium and contains very little iron. Its composition meant that the star must have arisen before iron became commonplace.
But more than two billion years older than your environment? Certainly this is simply not possible.
A closer look at the Methuselah era
Bond and his colleagues set themselves the task of determining whether or not this initial figure of 16 billion was. They compared more than 11 sets of observations recorded between 2003 and 2011 by the Hubble Space Telescope's Fine Orientation Sensors, which capture the positions, distances and energy output of stars. When receiving parallax, spectroscopy and photometry, a better sense of age can be determined.
"One of the uncertainties with the age of HD 140283 was the exact distance of the star," Bond told All About Space. "It was important to rectify this because we could better determine its luminosity and from that its age – the brighter the inner luminosity, the younger the star. We were looking for the parallax effect, which meant we were looking at star six months apart from looking for a change in position due to the orbital motion of the Earth, which tells us the distance. "
There was also uncertainty in the theoretical modeling of the stars, such as the exact rates of nuclear reactions in the nucleus and the importance of the elements that diverge down in in nshnite layers, he said. They worked on the idea that residual helium diffuses deeper into the nucleus, leaving less hydrogen to burn through nuclear fusion. When fuel is used faster, age decreases.
"Another important factor was that of all things, the amount of oxygen in the star," Bond said. HD 140283 has a higher than predicted oxygen-to-iron ratio, and since oxygen has not been abundant in the universe for several million years, it again indicates a lower age for the star.
Bond and his associates estimate the age of HD 140283 at 14.46 billion years – a significant decrease from the 16 billion previously claimed. However, this was more than the age of the universe itself, but scientists created residual uncertainty of 800 million years, which Bond said the star's age was compatible with the age of the universe, though not completely perfect.
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"Like all measured estimates, it is subject to both accidental and systematic errors," says physicist Robert Matthews of the University in Aston, Birmingham, United Kingdom, who did not participate in the study. "The overlap in the error bars gives some indication of the likelihood of a collision with cosmological determinations of age," Mathews said. "In other words, the best-supported star era is in conflict with that of the derivative era of the universe [as determined by the cosmic microwave background]. Conflict can only be resolved by pushing the error bars to their extreme limits."
In addition, the specs saw the age of HD 140283 drop a little more. A 2014 follow-up survey updates the star's age to 14.27 billion years. "The conclusion is that age is about 14 billion years and again, if one includes all sources of uncertainty – both in observation and theoretical modeling – the error is about 700 or 800 million years, so there is no conflict because 13.8 billion years are in the star's fault line, "Bond said.