SWIFT J1756.9-2508 is a millisecond pulsar

Millisecond pulsar

A millisecond pulsar is a pulsar with a rotational period in the range of about 1-10 milliseconds. Millisecond pulsars have been detected in the radio, X-ray, and gamma ray portions of the electromagnetic spectrum. The origin of millisecond pulsars is still unknown...

 with a rotation frequency of 182 Hz (period of 5.5 ms). It was discovered in 2007 by the Swift Gamma-Ray Burst Explorer and found to have a companion with a mass between 0.0067 and 0.030 solar mass

Solar mass

The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...

es. It is thought that the companion is the remnant of a former companion star, now stripped down to a planetary-mass core

Stellar structure

Stars of different mass and age have varying internal structures. Stellar structure models describe the internal structure of a star in detail and make detailed predictions about the luminosity, the color and the future evolution of the star....

. The pulsar

Pulsar

A pulsar is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name...

 is accreting mass from this companion, resulting in occasional violent outbursts from the accumulated material on the neutron star

Neutron star

A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...

.

External links

• Universe Today, Pulsar Has Almost Completely Devoured a Star
• SIMBAD, "SWIFT J1756.9-2508" (accessed 2010-11-06)