Parkes telescope finds new kind of star

Feb 16, 2006
Illustration of a pulsar showing magnetic field lines (cut away) and radio beam.
Illustration of a pulsar showing magnetic field lines (cut away) and radio beam. Credit: Russell Kightley Media

An international team of astronomers using CSIRO’s Parkes radio telescope in eastern Australia has found a new kind of cosmic object.

An international team of astronomers using CSIRO’s Parkes radio telescope in eastern Australia has found a new kind of cosmic object — small, compressed ‘neutron stars’ that show no activity most of the time but once in a while spit out a single burst of radio waves. The discovery will be published in this week’s issue of the journal Nature.

The new objects — dubbed Rotating Radio Transients or RRATs — are likely to be related to conventional radio pulsars (small stars that emit regular pulses of radio waves, up to hundreds of times a second). But the new objects probably far outnumber their old cousins, the scientists say.

Eleven RRATs have been found, first detected by the Parkes Multibeam Pulsar Survey and then observed again several times. Their isolated bursts last for between two and 30 milliseconds. In between, for times ranging from four minutes to three hours, they are silent.

'These things were very difficult to pin down,' says CSIRO’s Dr Dick Manchester, a member of the research team and a veteran pulsar hunter. 'For each object we’ve been detecting radio emission for less than one second a day. And because these are single bursts, we’ve had to take great care to distinguish them from terrestrial radio interference.'

By analysing the burst arrival times, the astronomers have found that 10 of the 11 sources have underlying periods of between 0.4 seconds and seven seconds. It is this that suggests that they are rotating neutron stars.

Because RRATs are ‘silent’ most of the time, the chance of being able to detect one is low. Many more must lurk unseen in our Galaxy, the astronomers argue — perhaps a few hundred thousand. The number of ‘normal’ radio pulsars in our Galaxy is estimated to be about 100,000.

Unlike some other kinds of stars that show periodic eruptions, the RRATs show no evidence for being in binary systems (that is, each orbiting another star).

A handful of ‘normal’ pulsars produce the occasional ‘giant’ pulse, along with their usual train of regular, smaller pulses. The RRATs appear to differ from these by having magnetic field strengths in the emission region about a hundred thousand times weaker.

The research team was drawn from institutions in the UK, USA, Australia, Canada and Italy.

Source: CSIRO

Explore further: The latest observations of interstellar particles

add to favorites email to friend print save as pdf

Related Stories

Now you see it, now you don't

Feb 22, 2006

Some stars emit radio waves fairly steadily, while some compact neutron stars flash like beacons in the sky. But others brighten and dim erratically, without any discernible pattern to the outbursts, according to Maura McLaughlin ...

Recommended for you

The Great Cold Spot in the cosmic microwave background

1 hour ago

The cosmic microwave background (CMB) is the thermal afterglow of the primordial fireball we call the big bang. One of the striking features of the CMB is how remarkably uniform it is. Still, there are some ...

Winter in the southern uplands of Mars

1 hour ago

Over billions of years, the southern uplands of Mars have been pockmarked by numerous impact features, which are often so closely packed that they overlap. One such feature is Hooke crater, shown in this ...

Five facts about NASA's ISS-RapidScat

1 hour ago

NASA's ISS-RapidScat mission will observe ocean wind speed and direction over most of the globe, bringing a new eye on tropical storms, hurricanes and typhoons. Here are five fast facts about the mission.

User comments : 0