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article imageScientists search for strange stars made of unknown matter

By Stephen Morgan     Nov 30, 2014 in Science
Scientists are trying to detect ripples in space-time in the hope of finding so-called "strange stars." They believe that these cosmic bodies are not made of any ordinary matter, so far known to exist in the universe..
We already know that matter is made up of protons and neutrons circling the nuclei of atoms and these, in turn, are composed of three quarks, which come in six forms, also called "flavors" - up, down, top, bottom and so-called charm and strange quarks. Neutrons are made up of two down quarks and one up quark and, conversely, protons are composed of two up and one down.
However, that may not be the end of the story. Theoretically, matter could be also made up of other types of quarks, in particular "strangelets" which would make up the basis of strange matter, something first proposed by scientists back in the 1970s.
Space.com says that the strangelets could be heavier and more stable than ordinary matter. Consequently, they could be changing ordinary matter into strange matter, although scientists have not yet been able to recreate this in laboratory experiments.
Astrophysicists think that strange matter could be forming naturally inside neutron stars. These stars are very small, measuring only 12 miles (19 kilometers) across on average. They are left overs from massive supernova explosions and, although tiny by cosmological standards, they are incredibly dense and could weigh as much as our own sun. Just a sugar cube portion of a neutron star could weigh 100 million tons.
The incredible forces compacted in this extreme density may be converting standard quarks into strange quarks, which in turn, are creating strange stars made up of strange matter. They would be even denser than neutron stars. For example, a neutron star, one-fifth the mass of our sun, would be more than 18 miles (30 km) in diameter, while a strange star of the same mass would be only 6 miles (10 km) wide.
Discovery.com reports that researchers believe that these strange stars could also be capable of shooting out strange matter which would zap orbiting neutron stars and change them into strange stars as well.
Research suggests that just a small amount of strange matter could transform a neutron star in only 1 millisecond to 1 second. Scientists think that this could be the explanation for two gigantic explosions, called gamma-ray bursts in deep space in 2005 and 2007, which lasted for only 2 seconds.
In order to confirm this, scientists are now looking for evidence of ripples in space-time, something proposed by Einstein's General Theory of Relativity. According to this, the larger the celestial object, the greater the gravitational waves which are produced and the merger of highly, dense neutron stars can have the same effect. But when strange stars merge, their even denser nature should give off gravitational waves different from neutron stars.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) was unable to detect any neutron star gravitational waves, which should have been present in the short gamma-ray bursts detected in 2005 and 2007 and scientists now suspect that the reason for this is the involvement of strange stars, which, because of their greater density, would have created gravitational waves at a higher frequency than was initially expected.
Now, by using the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO), they hope to re-examine the earlier results. The first more advanced observations will take place next year and they expect to be able to detect strange star/neutron star mergers every 8 years. Eventually with the new Einstein Telescope now being built in Europe, they expect to far surpass this, potentially detecting as many as about 700 mergers per year, or about two per day.
Lead researcher, Pedro Moraes, an astrophysicist at Brazil's National Institute for Space Research told Space.com that "The possibility of a re-analysis of LIGO signals for GRB 070201 and GRB 051103, taking into account some possible cases involving strange stars, is really exciting."
The gravitational waves scientists are searching for as evidence of strange stars have been described as the smoking gun of the Big Bang. Black holes orbiting neutron stars are one of the strongest sources of gravitational waves. If the existence of strange stars is confirmed, then how they interact with black holes may also provide us with more information about the undiscovered secrets of our universe.
The findings were published in the Nov. 21 issue of the journal Monthly Notices of the Royal Astronomical Society: Letters.
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