Space

Mysterious radio blips that come from apparently empty regions of space may be the voices of long-dead stars.

Thirteen unexplained radio blips have turned up in radio telescope observations since the 1980s. They emerged in spots where there are no stars or galaxies to be seen, last anywhere from hours to days, and do not seem to repeat. The blips could be traces of a vast population of stellar corpses – neutron stars that roam the universe largely unseen, suggests a team led by Eran Ofek of the California Institute of Technology in Pasadena.

Most of the galaxy's estimated billion neutron stars are invisible. Some of the newly formed ones have been detected because their rapid rotation sends radio pulses our way multiple times per second. These are thought to fade with age.

Gassy burps

If each of the neutron stars produces a radio burst every few months, perhaps after absorbing interstellar gas, the close ones would be detected at the rate observed, the team calculates.

"Neutron stars are a good possibility as the explanation for these events," says Geoffrey Bower of the University of California, Berkeley, whose team found seven of the outbursts in archived data from the Very Large Array telescope at the National Radio Astronomy Observatory near Socorro, New Mexico. "They are ubiquitous throughout the galaxy."

Bower and his colleagues plan to scrutinise the locations of the radio blips using the orbiting Chandra X-ray Observatory, looking for X-ray emissions characteristic of neutron stars.

See more: Ghostly gallery: Spooky images from space

Journal reference: arxiv.org/abs/0910.3676

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