Scientists, using NASA’s Hubble space telescope, have discovered a white dwarf star about 200 light-years from the Earth, whose atmosphere is rich in the building blocks for life – carbon, nitrogen, oxygen and hydrogen, the components of water.
Researchers from the University of California, Los Angeles (UCLA) in the US said that a minor planet in the planetary system was orbiting around the white dwarf and its trajectory was somehow altered, perhaps by the gravitational pull of a planet in the same system.
That change caused the minor planet to travel very close to the white dwarf, where the star’s strong gravitational field ripped the minor planet apart into gas and dust. Those remnants went into orbit around the white dwarf – much like the rings around Saturn, said Benjamin Zuckerman from UCLA – before eventually spiraling onto the star itself, bringing with them the building blocks for life.
Zuckerman said the study presents evidence that the planetary system associated with the white dwarf contains materials that are the basic building blocks for life. Although the study focused on this particular star -known as WD 1425+540 – the fact that its planetary system shares characteristics with our solar system strongly suggests that other planetary systems would also.
“The findings indicate that some of life’s important preconditions are common in the universe,” said Zuckerman.The researchers think these events occurred relatively recently, perhaps in the past 100,000 years or so, said Edward Young from UCLA. They estimate that about 30 per cent of the minor planet’s mass was water and other ices, and approximately 70 per cent was rocky material. The research suggests that the minor planet is the first of what are likely many such analogs to objects in our solar system’s Kuiper belt.
The Kuiper belt is an enormous cluster of small bodies like comets and minor planets located in the outer reaches of our solar system, beyond Neptune. Astronomers have long wondered whether other planetary systems have bodies with properties similar to those in the Kuiper belt, and the new study appears to confirm for the first time that one such body exists.
White dwarf stars are dense, burned-out remnants of normal stars. Their strong gravitational pull causes elements like carbon, oxygen and nitrogen to sink out of their atmospheres and into their interiors, where they cannot be detected by telescopes. The research describes how WD 1425+540 came to obtain carbon, nitrogen, oxygen and hydrogen.
This is the first time a white dwarf with nitrogen has been discovered and one of only a few known examples of white dwarfs that have been impacted by a rocky body that was rich in water ice.”If there is water in Kuiper belt-like objects around other stars, as there now appears to be, then when rocky planets form they need not contain life’s ingredients,” said Siyi Xu from UCLA.
The study was published in the Astrophysical Journal Letters.