The first new class of compact cosmic objects in 70 years!

Johan Hansson & Fredrik Sandin, Luleċ University of Technology

Article about our "preon stars" in New Scientist ("The World's No.1 Science & Technology Magazine")
6 November 2004, p.19
New Scientist Magazine

"Micro-stars may manage to avoid black-hole fate"

New Scientist vol 184 issue 2472 - 06 November 2004, page 19
COULD the universe be filled with strange stars the size of footballs? Perhaps, if the big bang fireball churned out superdense stars just a few tens of centimetres wide. And contrary to conventional theory, such stars might even form today when ordinary stars explode.
When a massive star runs out of fuel at the end of its life, it collapses and explodes. If a core about 2 or 3 times as massive as the sun remains, it forms a neutron star, a superdense ball of nuclear matter typically 10 kilometres wide. And if the core is heavier, it should collapse into a black hole.
But now Johan Hansson and Fredrik Sandin of Luleċ University of Technology in
Sweden have suggested a third possibility, based on the properties of hypothetical particles called preons. Some theorists believe preons could be the building blocks of elementary particles such as quarks and electrons. Preons, they say, could halt the collapse into a black hole and end up forming a football-sized preon star.
Their calculations suggest a preon star would form when matter reached a density of about 10
17 tonnes per cubic centimetre. This makes preon balls even more likely to have formed in dense regions of the big bang fireball than in collapsing stars. To be stable, a preon star would have to have a radius of between roughly a tenth of a millimetre and a metre, and a mass up to 100 times that of the Earth ( However, these stars might not emit much light, which could explain why they have not been spotted, they say.
Preon stars would be somewhere around the size of a football, with a mass up to 100 times that of the Earth
Rabindra Mohapatra, a physicist at the University of Maryland in College Park, says that preon models are not wildly popular today because they do not explain the properties of elementary particles neatly enough. "Preon models have gone out of fashion, but there is nothing in the domain of experiments that contradicts the idea."

Hazel Muir


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