Have you ever wondered what star in our record books is considered the oldest star in the universe? Well Hubble Space telescope studied the Methuselah star and retrieved some interesting data. They found a star to be 14.5 billion (+/- .8 billion) years old and it’s located right in our own Milky Way! The distance of the star was calculated to be 190.1 light years away from Earth. Even though there is a large amount of commotion saying it is older than the universe some say it isn’t. There is a margin of error that goes along with predicting the age of a star and for Methuselah star it is about a 800 million year difference. It’s still quite close to the beginning of the universe which is still fascinating and a question that is provoking is if our theory of the big bang is facing danger because this data goes against what we know about cosmology. Nonetheless, the age estimate of this star have dramatically dropped down from 15-16 billion years to the current 14.5 billion. Let’s dive more into this story and find out how did they exactly find out how old this star is and a little backstory to how this data came about.
How Did They Figure Out How Old the Methuselah Star is?
A common question asked is how does an astronomer even know how old a star is? Well they look at a couple of different pieces of data to put the puzzle together. First they determine the distance of a star by finding out what the parallax is of a star. Here is an image of what that means:
Credit: http://spaceinimages.esa.int/Images/2013/06/The_parallax_method_of_measuring_a_star_s_distance
After performing the proper calculations astronomers can then calculate the true distance from Earth to the star through triangulation. Then astronomers can use this data to calculate the intrinsic brightness. Knowing the intrinsic brightness is a fundamental prerequisite to predict the age of a star. In addition to calculating the age of a star astronomers study the deficiency of heavier elements in the star comparing it to stars in the galactic neighbourhood. An interesting fact is the Methuselah star did not originate in the Milky Way. In fact scientists believe it came from a dwarf galaxy that collided with the Milky Way and was consumed. Some evidence to back up this theory up is the speed at which the star travels. It travels 800,000 miles per hour which is very fast (compared to our Sun which travels at 486,000 miles pr hour). Going back to the point about calculating the deficiency of heavier elements they found that the Methuselah star was 1/250 more deficient than our own Sun’s. Many of the first inhabitant stars were not exposed to the pollution of heavier elements because they were rare in the early universe (because no supernova’s were happening yet). The Methuselah star (or catalogued as H D 140283) has been known about for over a century. There have been estimates on the age of this star and it’s only getting more and more precise as our instruments are getting more advanced. The star is in its first stage of becoming a red giant (which is the fate of our Sun’s in 5 billion years!). The star does provoke the scientific communities mind as well as our own to understand how stars like these formed and what the early universe was like. If you would like to learn more about this you can read the official publication here