The star HD 140283 is called the “Star of Methuselah” due to its extreme age. It is estimated to be over 14 billion years old and is considered the oldest star known within our galaxy.
Surprisingly, it can be seen with binoculars and appears to be older than the universe itself. This raises the question of how this is possible.
The standard estimate of the time since the Big Bang is 13.79 billion years. This figure is based on the rate of expansion of the universe using Einstein’s theory of relativity and has been confirmed by various methods. However, this estimate is currently facing at least three different challenges.
Proponents of alternative theories point to the existence of stars estimated to be either over 13.8 billion years old or those that are so close to that age that they should not have had enough time to form.
HD 140283 received a “premium rating” in a 2013 study using Hubble data, which estimated its age to be 14.46 billion years, give or take 800 million years. This would potentially make it older than the universe itself.
The biggest claim regarding HD 140283 is that it challenges the Big Bang theory. If there is even one star that is 14.5 billion years old, it suggests that the explosion that started the universe could not have occurred less than 14 billion years ago. The Big Bang theory is so central to our cosmology that if it were disproven, it would lead to a significant scientific revolution.
Accommodating the recent claim that the Big Bang happened almost twice as long ago as most estimates suggest, 26.7 billion years ago, would require a smaller but still significant change. However, neither view has the support of astrophysicists.
Some suspect that our estimates of the time of the Big Bang may be somewhat erroneous and that the universe is actually about 15 billion years old. If this were proven, it would raise questions about the accuracy of our estimates of the expansion rate of the universe, but the changes in our thinking would be evolutionary rather than revolutionary.
If the universe were 26 billion years old, we might expect to find stars that are 20 billion years old. However, while we have only studied a small part of the galaxy, HD 140283 appears suspiciously young if the universe is that old. This raises the question of what we might expect to see if the universe had no beginning and has always existed.
Outside the Milky Way, the stars in the globular cluster M92 are believed to be about 13.8 billion years old. The James Webb Telescope (JWST) has also found several very distant galaxies whose age is still disputed, but none of them appear significantly older than HD 140283.
It is possible that our methods for estimating the age of stars could be more reliable. Many potential sources of error are not always included in the error calculations provided.
HD 140283 serves as an outstanding example of this. In addition to the estimate of 14.46 billion years, another team has given ages of 13.7 billion and 12.2 billion years, depending on which estimate of its mass is considered correct.
The age of stars is usually estimated from their absolute brightness and composition. The early universe contained nothing but hydrogen and helium. Most of the heavier elements were formed only as a result of the death of first-generation stars.
The lower the concentration of these elements, the older the star is considered. However, this is not an ideal method. Not only can our measurements be wrong, but the heavy metals of the first supernovae may not have always mixed evenly. Other methods have been proposed but are still being tested.
Even if the 14.46 billion year figure is correct, a slightly older universe is a much more plausible explanation than one that formed 13 billion years earlier than thought or had no beginning at all.
