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Star in final stages of life still sports solar system

The Herschel space observatory has discovered an eerie dying solar system, complete with a debris disc and planets still orbiting an ever expanding and dying star.

A team of scientists working for the European Space Agency, ESA, have discovered a solar system containing an expiring star of roughly 1.5 solar masses in its “subgiant” phase. The subgiant phase is the period at the end of a star’s life when it begins to expand due to the dwindling supply of fuel for its fusion reaction, but comes before it fully expands to become a red giant. This star, which is roughly 100 light years away and 2.5 billion years old, is notable because it is surrounded by a disc of gas and still hosts a planetary system.

It has been expected previously that asteroids, planets and other bodies in a solar system can survive during the subgiant phase, but until now, they haven’t been observable, and thus, no research into their properties has been possible. Thanks to the Hershel space observatory’s far-infrared equipment however, astronomers have been able to detect a bright emission, indicating a dust disc, around the dying star, which is named Kappa Coronae Borealis. In addition, ground based observations have confirmed a Jupiter-sized gas giant orbiting at a distance equivalent to that of our asteroid belt, and it is suspected that a second planet also exists, though the size of it has yet to be confirmed.


Here's the star in question, complete with the dust disc, as seen in bright white


The most unique feature of the solar system is the gaseous disc, which has survived through the entire lifespan of the star, something which is very much different from how the conditions of our own solar system have evolved. Sol had a dust disc too, but during a period known as the Late Heavy Bombardment Era, most of the gasses were cleared away. As of yet there are multiple explanations floating about as to why this disc has survived.


Nevertheless, this is the first time a solar system in its subgiant phase has been discovered to have planets and it provides a unique opportunity to study not just the disc, but what happens to the system in general as time goes on. After all, one day, our own system will face a similar fate.

David F.
A grad student in experimental physics, David is fascinated by science, space and technology. When not buried in lecture books, he enjoys movies, gaming and mountainbiking

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