Methuselah star or HD 140283 is a metal-poor subgiant star around 200 light-years away from the Earth in the constellation Libra, near the edges with Ophiuchus in the Milky Way Galaxy. Its likely magnitude is 7.205. The star’s light is somewhat blueshifted as it is running toward rather than away from us and it has been known to astronomers for over a century as a high-velocity star based on its other vectors (proper motion). It seems like any other star, right? Read below.
- In 2000, explorers sought to date Methuselah Star using observations via the European Space Agency’s (ESA) Hipparcos satellite, which measured the age of 14.5 billion years old. Such a figure was rather mind-blowing and also pretty baffling. Why? Because the age of the Universe is 13.7 billion years. How can Methuselah Star be older than the Universe? Older than Big Bang? Scientists are still puzzled.
- Scientists have known about HD 140283 for more than 100 years since it sails across the sky at a comparatively rapid clip. The star moves at about 800,000 mph (1.3 million km/h) and reaches the width of the full moon in the sky every 1,500 years or so. The star is just crawling through the Earth’s neck of the galactic woods and will ultimately rocket back out to the Milky Way’s halo, a population of ancient stars that encompasses the galaxy’s familiar spiral wheel.
- The Methuselah star, which is just now growing into a red giant, was born in a dwarf galaxy that the nascent Milky Way ate up more than 12 billion years ago, researchers conclude. The star’s long, looping orbit is likely a residue of that climactic act of star eating itself.
- Hubble’s dimensions allowed the astronomers to refine the distance to HD 140283 using the principle of parallax, in which a variation in an observers’ position — in this case, Hubble’s changing position in Earth orbit — turns into a shift in the visible position of an object. They found that Methuselah lies 190.1 light-years away. With the star’s extent known more precisely, the team was able to work out Methuselah’s intrinsic brightness, a requirement for determining its age.
- The scientists also employed current theory to learn more about the Methuselah star’s burn rate, structure, and organic composition, which also cast light on its likely age. For example, HD 140283 has a comparatively high oxygen-to-iron ratio, which brings the star’s age down from some of the earlier predictions, researchers conclude. In the end, the astronomers determined that HD 140283 was born 14.5 billion years ago, plus or minus 800 million years.