Astronomers observe final moments of planetary remnants for the first time

Coventry [England], February 10 : A white dwarf is known to be a small very dense star that is typically the size of a planet. It is formed when a low-mass star has exhausted all its central nuclear fuel and lost its outer layers as a planetary nebula. Astronomers at the University of Warwick, for the first time, observed the moment that debris from destroyed planets impacted the surface of a white dwarf star.

The results of their study were published in the journal 'Nature'.

They used X-rays to detect the rocky and gaseous material left behind by a planetary system after its host star dies as it collides and is consumed within the surface of the star.

The results were the first direct measurement of the accretion of rocky material onto a white dwarf, and confirmed decades of indirect evidence of accretion in over a thousand stars so far. The observed event occurred billions of years after the formation of the planetary system.

The fate of most stars, including those like our Sun, is to become a white dwarf. Over 300,000 white dwarf stars have been discovered in our galaxy, and many are believed to be accreting the debris from planets and other objects that once orbited them.

For several decades, astronomers have used spectroscopy at optical and ultraviolet wavelengths to measure the abundances of elements on the surface of the star and work out from that the composition of the object it came from. Astronomers have indirect evidence that these objects are actively accreting from spectroscopic observations, which show 25-50 per cent of white dwarfs with heavy elements such as iron, calcium, magnesium polluting their atmospheres.

Until now though, astronomers had not seen the material as it was pulled into the star.

( Details and picture courtesy ANI, the content is auto-generated from feed.)

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