A new species of &132Starcorpse predicted
Astronomers have modeled their development on the basis of theoretical calculations and observations of binary star systems. According to this, in some cases an already extinct star can snatch matter from its partner until its last spark of life has gone out. Shrunk to the size of the planet Jupiter, it no longer had enough hydrogen to glow on its own. An international team of astronomers led by Dr. Steve Howell from the University of Wyoming has discovered the new type of star. Howell, associate professor in the Department of Physics and Astronomy, along with colleagues tried to understand the life cycle of stars within very old binaries. Many stars originally form as binary systems, with two stars orbiting each other for all existence, held together by their gravitational pull. Some binary stars are so close together that their orbits would fit the size of our sun. Through this closeness, they also influence each other's lives.
Howell and his collaborators used observations from some of the world's largest telescopes and theoretical models run on supercomputers to develop new theories about the evolution of these ancient binary systems. They now believe that a new type of star exists within some of these systems.
The discovery of a new type of star is not an everyday event, says Howell. "At the beginning of this century, astronomers relied on both theory and observation to discover white dwarfs, neutron stars, and black holes. And to this day, no other "star corpses" have been found.
Stars shine because of the release of energy within them, mainly from the fusion of hydrogen into helium. Once the hydrogen is depleted, a star must rearrange its overall structure to resist collapse from the ever-present gravitational force. After a relatively short span of a few million years, stars generally end their lives as one of three stellar end products: a white dwarf, a neutron star, or a black hole. The latter is the final stage of the most massive stars.
In many binaries, the initially more massive star ends its life and becomes a white dwarf, while the originally less massive star tries to evolve normally, all the while losing mass to the white dwarf explains Howell. All that is ultimately left is an unprotected stellar core about the size of the planet Jupiter and a mass of just 5 percent of the initial value. After this extremely small star has used up or lost almost all of its hydrogen, it can no longer generate any energy. It can then no longer even become one of the usual stellar end products. Because of this, it has a structure unlike any other known type of star.
Howell adds: It is gratifying to know that the universe still holds mysteries and that through diligence and patience we can peek inside and discover some small new parts for ourselves.
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