An international team of astronomers has made a remarkable discovery—a pair of stars that are about 10 billion years old and originated from the farthest reaches of the Milky Way galaxy.
These two stars, which have been journeying from the outskirts of our galaxy, were found surprisingly close to Earth.
The discovery was made by researchers from the UK, Spain, and China, including experts from the University of Hertfordshire.
This unusual pair is known as a binary star system, meaning the two stars are gravitationally bound and orbit around each other.
The stars in this system have been identified as a white dwarf and an ultracool subdwarf.
These stars usually reside in the Milky Way’s halo, a distant and sparsely populated region surrounding our galaxy.
However, their eccentric orbit occasionally brings them into the central area of the Milky Way, where most of the galaxy’s mass lies.
The white dwarf star, named VVV1256-62A, is particularly intriguing because it has been cooling down for billions of years.
White dwarfs are the remnants of regular stars that have exhausted their fuel and no longer undergo active fusion. Although they start off extremely hot, white dwarfs gradually cool over time.
By calculating how much this star has cooled, the researchers were able to estimate its age, determining that it is roughly half the mass of our sun.
The second star, VVV1256-62B, is a low-metallicity subdwarf, meaning it contains very few elements heavier than hydrogen and helium.
In the early stages of the Milky Way, there were fewer heavy elements, so stars with low metallicity are considered to be ancient.
This star’s low metal content gives scientists important clues about the early history of our galaxy.
Additionally, this subdwarf lies at the boundary between being a star and a substellar object, making it a valuable reference point for studying ancient, metal-poor stars.
The discovery of this binary system, with its highly eccentric orbit, provides new insights into the structure and history of the Milky Way.
The reason for this unusual orbit is still unclear, but it might be connected to the presence of an inner halo or perhaps a past merger between the Milky Way and another galaxy.
This breakthrough was made possible with the help of powerful telescopes around the world, including the Gemini South telescope in Chile and the Very Large Telescope of the European Southern Observatory.
The study also involved researchers who are current and former Ph.D. students at the University of Hertfordshire.
Professor Hugh Jones, an astronomy professor at the University of Hertfordshire, expressed pride in his students’ contributions to this discovery, stating that it opens up new possibilities for understanding the formation of the Milky Way and its complex structure.
Source: KSR.
