Known as the Methuselah star, HD 140283 holds the title for being the oldest known star in the Milky Way galaxy. This remarkable discovery has intrigued astronomers and has significantly contributed to our understanding of the universe’s early stages. HD 140283 was identified through its relatively rapid velocity in moving towards the Earth, qualities initially observed during its discovery in the early 20th century. Subsequent analysis revealed that it is an ancient subgiant star, which has evolved from being a main sequence star.
HD 140283's astounding age, estimated to be over 13.6 billion years, places its birth very close to the Big Bang, which is thought to have occurred around 13.8 billion years ago. This proximity in time to the Big Bang poses interesting challenges and opportunities for astronomers. Multiple techniques, including parallax measurements obtained by the Hubble Space Telescope, have been employed to refine estimates of its age and other characteristics. These observations have also confirmed that HD 140283 has a very low metallicity, meaning it contains very small amounts of elements other than hydrogen and helium, which are indicative of very ancient stars formed before heavier elements were more abundant in the universe.
The study of HD 140283 not only provides information about the conditions of the early universe but also about the processes of star formation and evolution that occurred in the galaxy's formative years. The Methuselah star is considerably more than a mere beacon of the distant past; it serves as a critical benchmark for testing the limits of our physical theories related to the cosmos and aids in refining models of stellar dynamics and aging.
Additionally, HD 140283's incredible longevity and its survival through vast epochs of cosmic history provide a unique perspective on the resilience and the potential lifespans of stars. This ancient luminary travels through our galaxy in an elongated orbit, allowing it to periodically come closer to Earth, presenting astronomers with opportunities to study it in detail. Living through major changes in the galactic neighborhood, the Methuselah star offers insights into the Milky Way’s own development and the transformation of its stellar population over billions of years. Hence, HD 140283 not only holds a record for its age but also serves as a valuable subject in the ongoing quest to understand our universe's past and its future.
