Link up will shed more light on extreme stars

22 Apr 2010

A ground breaking link up of three telescopes is to provide us with new insight into the Universe’s most extreme stars.

Telescope link up provide new insight
Telescope link up provide new insight

An International team of astronomers used the new European LOFAR telescope combined with two of the world's largest radio telescopes, the Lovell telescope at Jodrell Bank-part of The University of Manchester and  the Effelsberg telescope in Germany, to understand more about the enigmatic radio emitting stars called Pulsars.

The unique combination of telescopes allowed the team to simultaneously observe the radio waves from six different pulsars across wavelengths from only 3.4 centimetres up to 7 meters - a factor of 200 difference and the highest achieved anywhere in the world.

The different wavelengths of radio light can be compared to the different colours perceived by the human eye and provide an unprecedented view of how radio pulsars shine.

Pulsars are rapidly rotating neutron stars, which measure only about 20 kilometers across and yet are more massive than the Sun and are therefore the second only to blackholes in terms of their density.

They have very strong magnetic fields which produce beams of radio light from their magnetic poles, which are observable over a wide range of wavelengths.
For the last 40 years astronomers have been studying pulsars and are getting closer to understanding the mechanism that generates these intense beams.

They hypothesize that the emission seen at the different wavelengths emerges from different heights above the highly magnetized pulsar surface.

Emission seen at a particular radio wavelength therefore provides a slice through the pulsar's surrounding "magnetosphere"  - magnetized atmosphere.

The shape of the pulsar's pulsed emission is seen to evolve quite drastically as a function of wavelength and maps the spreading of magnetic field lines above the pulsar's magnetic poles.

Dr Ben Stappers, from The University of Manchester, said: "Not only do such observations give us a fantastic handle on understanding the emission of pulsars, they are also a powerful probe of the interstellar gas that is between us and the pulsar.
“We hope that this effort will enlighten us all further on these most fascinating objects.”

The LOFAR telescope, spanning more than 1000 kilometres in Europe, will be completed next year to become Earth’s most powerful telescope for observing the Universe at the longest possible radio wavelengths visible from the Earth's surface: 1-30 meters.

“These observations provide us with a glimpse of  the  many exciting new scientific results this telescope will provide”, added Dr Stappers.

Jason Hessels of ASTRON Netherlands Institute for Radio Astronomy  said: "For comparison, consider that we have simultaneously observed these pulsars over a range equivalent to all the tones spanned by a piano,

"By simultaneously observing these pulsars at such a wide range of wavelengths, we can make many snapshots of what the pulsar's emission looks like at a range of heights above the star's magnetic poles.”.
Michael Kramer, director at the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn and the University of Manchester is excited about the enormous extension in wavelength coverage provided by LOFAR, of which the first international antenna station was built next to the Effelsberg telescope in Germany.
He said: "These observations show how LOFAR complements the existing radio telescopes in Europe, like the 100-m Effelsberg telescope and the 76-m Lovell telescope, in a nearly perfect way.”
Aris Karastergiou of the University of Oxford said: "It is truly amazing that an array of dipoles and some hi-tech electronics in a field in Chilbolton, Hampshire, will soon also provide such a sensitive detector of pulsar signals in the UK.

“We will make the most of the received signals by analyzing them with super fast computer hardware, similar to what is found in modern gaming consoles".

Notes for editors

Image: Simultaneous detection of pulses from pulsar PSR B1133+16 in four widely spaced wavelength bands ranging from 3.4 cm to 7 m. The Effelsberg telescope is centered at 3.6 cm wavelength, the Lovell telescope at 21 cm wavelength, and LOFAR high-band (HBAs) and low-band antennas (LBAs) at 170 cm and 430 cm wavelength, respectively. The shape of the radio pulse maps the spreading of magnetic field lines above the pulsar's magnetic poles.

The LOFAR telescope is being primarily built by ASTRON Netherlands Institute for Radio Astronomy, in collaboration with a number of international partners.  The Effelsberg telescope is run by the Max Planck Institute for Radio Astronomy (MPIfR) in Germany. 
The Lovell telescope is part of the Jodrell Bank Observatory, which is run by the University of Manchester in England.
For Jodrell Bank media enquires contact:

Mike Addelman
Media Relations
Faculty of Humanities
The University of Manchester
0161 275 0790
07717 881567

Further Information:
Max Planck Institute for Radio Astronomy (MPIfR).
Fundamental Physics in Radio Astronomy Group at MPIfR.
Netherlands Institute for Radio Astronomy (ASTRON).
Jodrell Bank Centre for Astrophysics .
LOw Frequency ARray (LOFAR), International Web site.
LOw Frequency ARray (LOFAR), German Web site.
Parallel and Earlier Press Releases:
Eine Schwarze Witwe im Reich der Sterne (in German), PRI (MPIfR) 02/2010 (1), February 19, 2010.