A faint white dwarf located 90 light years from Earth is the oldest star ever found in our galaxy, and it is home to the remnants of a planetary system.
Scientists from the University of Warwick have spotted what is believed to be the most ancient star in the Milky Way Galaxy. It is accreting debris from orbiting planetesimals. This means that scientists have also located one of the oldest rocky and icy planet systems to date. Their findings are published in the Monthly Notices of the Royal Astronomical Society. They conclude that a faint white dwarf located 90 light years from Earth, as well as the remains of its orbiting planetary system, are over ten billion years old. The scientists found that the white dwarf is over ten billion years old, as is the planetary system orbiting it. They reported their findings in the Monthly Notices of the Royal Astronomical Society. The system is located some 90 light-years from Earth.
Why is it significant?
Stars like the Sun are destined to become white dwarfs. Stars that have burned up their fuel and shed their outer layers are known as white dwarfs. They are shrinking and cooling as they undergo this process. As a result, any planets orbiting the white dwarf will be disrupted or destroyed. Also, their debris will be left to accumulate on their surface. In this study, the team of astronomers modeled two unusual white dwarfs reported by the European Space Agency’s space observatory GAIA. A team of researchers examined both stars for evidence of planetary debris. One appeared to be unusually blue, while the other was the faintest and reddest in the local galaxy.
Age matters
How did they figure out how long the ‘red’ star has been cooling? Astronomers used data from GAIA, the Dark Energy Survey, and the European Southern Observatory’s X-Shooter instrument. They calculated its age to be about 10.7 billion years, of which 10.2 billion years were spent cooling as a white dwarf. By analyzing light at different wavelengths, spectroscopy allows us to determine the elements present in a star’s atmosphere by detecting their absorption of light and calculating their amounts. Additionally, as a result of analyzing the spectra from WDJ2147-4035, the team detected sodium, lithium, and potassium in the star. Scientists also detected carbon accreting onto it. This makes it the oldest metal-polluted white dwarf discovered to date.
Oldest planetary system in the Milky Way
This second ‘blue’ star was also polluted by planetary debris of a similar composition to Earth’s continental crust and is only slightly younger than WDJ2147-4035. Scientists concluded that WDJ1922+0233’s blue color is due to the unusual mix of helium and hydrogen in its atmosphere, despite its cool surface temperature.WDJ2147-4035 has a nearly pure helium atmosphere and high gravity, and the debris discovered on its surface is from an old planetary system that survived the evolution into a white dwarf. According to astronomers, this is the oldest planetary system in the Milky Way around a white dwarf.
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