Dark matter makes Milky Ways stars extend their lifetimes by a billion years

October 3rd, 2008 - 2:32 pm ICT by ANI  

London, Oct 3 (ANI): A new study has suggested that s tars at the centre of the Milky Way could gobble up enough dark matter to extend their lifetimes by a billion or more years.

According to a report in New Scientist, if such stars are found, they could help reveal what the mysterious dark matter is actually made of.

Although it constitutes roughly 90 percent of the Milky Ways mass, dark matter is thought to be too diffuse in most parts of the galaxy to have a large effect on stars.

But, close to the colossal black hole at the galactic centre, the material might be sufficiently dense that stars can capture it at high rates.

To investigate dark matters effect on such stars, Pat Scott of Stockholm University in Sweden and colleagues modeled the evolution of stars as they gravitationally accumulated weakly interacting massive particles, or WIMPs a popular group of dark matter candidates.

The team found that some stars orbiting less than 0.3 light years from the centre of the Milky Way could capture WIMPs in large quantities.

To do so, the stars must be on elongated rather than circular orbits, since these allow them to move slowly enough at points far from the galactic centre to grab dark matter particles.

Once caught, the dark matter particles would collide with gas in the star, losing energy so they would eventually settle at the stars centre.

There, the WIMPs would hit each other and annihilate, creating a blast of energy that would puff up the star.

This expansion would slow down the rate at which the star burns energy, and cause the star to appear redder than its mass would suggest.

If the stars were relatively puny roughly the mass of the Sun, they could accumulate enough dark matter to extend their lives by a billion years or so.

According to Fabio Iocco of the National Institute for Astrophysics in Firenze, Italy, this new study boasts the most detailed calculations yet of how ordinary stars might capture WIMPs.

If such stars exist and astronomers can peer through the intervening gas and dust in the Milky Way to find them, they could provide the first direct evidence of dark matter, according to Igor Moskalenko of Stanford University in California.

If there is even a single star with the predicted properties found there, it will be direct evidence that astrophysical dark matter consists of WIMPs and not something else a major breakthrough, Moskalenko told New Scientist. (ANI)

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