A research team led by West Virginia University astrophysicist Maura McLaughlin has discovered high-energy X-ray pulsations coming from a mysterious type of collapsed star.
The team recently used data from the space telescope, XMM -Newton, to detect a strange kind of neutron star known as a rotating radio transient (RRAT). Its findings were published in The Astrophysical Journal in December.
This is the first time X-ray pulsations have been detected from a RRAT , said McLaughlin, an assistant professor in the Department of Physics in WVU s Eberly College of Arts and Sciences. Previously astronomers had only seen radio outbursts from these objects.
A neutron star is the collapsed remnant of a massive star. Most are seen as radio pulsars, rotating quickly and sweeping lighthouse beams of radiation across space.
The RRATs, however, appear to rotate much more slowly. McLaughlins team first detected RRATs through bursts of radio waves. Only one burst is seen at a time, and the average time intervals between bursts range from four minutes to three hours.
Its a puzzle how RRATs fit in with other types of collapsed stars.
There are some interesting theories; one suggests RRATs are actually pulsars with asteroid belts around them,said McLaughlin, who was the lead author of a 2006 Nature paper announcing the discovery of RRATs.
The recent observations were made using XMM -Newtons European Photon Imaging Camera, which targeted the celestial object, RRAT J1819 1458. Astronomers observed this object for around 12 hours and detected pulsations in the X-ray data that show it to be rotating once every 4.26 seconds.
XMM -Newton is a joint NASA -European Space Agency orbiting observatory, designed to observe high-energy X-rays emitted from exotic astronomical objects such as pulsars, black holes and active galaxies.
Since the original discovery of 11 RRATs, McLaughlins team has found an additional 10. WVU students Dominic Ludovici of Morgantown and George Habib of Egypt have assisted McLaughlin in her search.
The discovery of this new source population means that the number of neutron stars in the Milky Way is likely much greater than previously thought, according to the WVU astrophysicist.
We can now estimate there could be more than 300,000 neutron stars in the galaxy,she said.
McLaughlins pulsar work with observatories around the world, including the National Radio Astronomy Observatory at Greenbank, has significantly expanded WVU s program in astrophysics. The WVU researcher was part of an international team that discovered the first known double pulsar some 2,000 light-years away from Earth.
More information on the RRAT observations is available at the European Space Agency Web site:http://www.esa.int/esaSC/SEMJJF2MDAF_index_0.html.