(ORDO NEWS) — The moment when fragments of destroyed planets fall on the surface of a white dwarf was observed by astronomers for the first time in the history of science.
They used X-ray observations to detect the rocky and gaseous material left over from the planetary system after the death of the parent star, which falls to the surface of the white dwarf and is absorbed by it.
These results are the first direct measurements of the accretion of rocky material on the surface of a white dwarf and confirm many years of indirect evidence of material accretion obtained to date for thousands of stars. The observed event occurred billions of years after the formation of the planetary system.
For several decades, astronomers have used optical and ultraviolet spectroscopy to measure the concentrations of elements on the surface of a star and use them to calculate the composition of the original object itself.
Astronomers had indirect evidence from such spectroscopic observations that these objects were actively accreting matter.
According to these data, 25 – 50 percent of the number of white dwarfs, in which heavy elements such as iron, calcium, magnesium were found, have atmospheres polluted by the remnants of planetary systems.
However, until now, scientists have not been able to observe the process of falling material onto a star.
Study lead author Dr Tim Cunningham, from the Department of Physics at the University of Warwick, UK, said: “We were finally able to see material entering the star’s atmosphere.
For the first time, we have been able to calculate the accretion rate, regardless of the use of any particular model of a white dwarf’s atmosphere. It is noteworthy that the result obtained is in good agreement with what was obtained earlier.”
“Previously, accretion rate measurements were based on spectroscopic observations and the use of detailed models of white dwarfs.
These are numerical models that allow you to calculate how quickly an element sinks into the atmosphere of a star, and this tells us how much material falls into the atmosphere – that is, gives a value for the accretion rate.
Then, using these data, it is possible to restore the elemental composition of the original parent body, to understand whether it was a planet, a satellite of a planet, or an asteroid.”
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