Because HD 140283 is neither on the
main sequence nor is a
red giant, its early position in the
Hertzsprung–Russell diagram has been interpreted with its data and theoretical models of
stellar evolution based on
quantum mechanics and the observations of processes in millions of stars to infer its apparent old age. For field stars (as opposed to stars in
clusters), it is rare to know a star's luminosity, surface temperature, and composition precisely enough to get a well-constrained value for its age. Because of their relative scarcity, this is even rarer for a population II star such as HD 140283. A study published in 2013 used the
Fine Guidance Sensors of
NASA's Hubble Space Telescope to measure a precise parallax (and therefore distance and
luminosity) for the star. This information was used to estimate an age for the star of billion years. Due to the uncertainty in the value, this age for the star would possibly conflict with the calculated
age of the Universe as determined by the final 2018
Planck satellite results of
billion years. Subsequent models of its stellar evolution have suggested revision of the star's age to 13.7 billion years the star must have formed soon after the Big Bang Most stars from population II and
population III are no longer observable. Studies of the star also help astronomers understand the Universe's early history. Very low but non-zero
metallicities of stars like HD 140283 indicate the star was formed from existing materials in the second generation of stellar creation; their heavy-element content is believed to have come from zero-metal stars (
population III stars), which have never been observed. Those first stars are thought to have been formed from existing materials a few hundred million years after the Big Bang, and they died in explosions (
supernovae) after only a few million years. By 2018,
parallax measurements by the
Gaia on its second catalogue,
Gaia DR2, implied a distance of with an error of 0.44%, which was later improved to in the
Gaia DR3 Catalog. This is significantly higher than the in the
Hipparcos catalogue and from a Hubble parallax, which were used in the previous age estimates, and imply a larger
stellar mass and hence a lower age. An age of billion years was estimated in 2022 using evolutionary models and
interferometric observations, while a more detailed study in 2024 found an age between 12 and 14 billion years, depending on the chemical abundances used. A 2025 study using
asteroseismology found a more precise age of billion years, which is still in agreement with the age of the Universe within one
standard deviation. ==See also==