Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

XMM-Newton sees ’hot spots’ on neutron stars

25.04.2005


X-ray image of the neutron star ’Geminga’


Thanks to data from ESA’s XMM-Newton spacecraft, European astronomers have observed for the first time rotating ‘hot spots’ on the surfaces of three nearby neutron stars.

This result provides a breakthrough in understanding the ‘thermal geography’ of neutron stars, and provides the first measurement of very small-sized features on objects hundreds to thousands light-years away. The spots vary in size from that of a football field to that of a golf course.

Neutron stars are extremely dense and fast-rotating stars mainly composed of neutrons. They are extremely hot when they are born, being remnants of supernovae explosions. Their surface temperature is thought to gradually cool down with time, decreasing to less than one million degrees after 100 000 years.



However, astrophysicists had proposed the existence of physical mechanisms by which the electromagnetic energy emitted by neutron stars could be funnelled back into their surface in certain regions. Such regions, or ‘hot spots’, would then be reheated and reach temperatures much higher than the rest of the cooling surface. Such peculiar ‘thermal geography’ of neutron stars, although speculated, could never be observed directly before.

Using XMM-Newton data, a team of European astronomers have observed rotating hot spots on three isolated neutron stars that are well-known X-ray and gamma-ray emitters. The three observed neutron stars are ‘PSR B0656-14’, ‘PSR B1055-52’, and ‘Geminga’, respectively at about 800, 2000 and 500 light-years away from us.

As for normal stars, the temperature of a neutron star is measured through its colour that indicates the energy the star emits. The astronomers have divided the neutron star surfaces into ten wedges and have measured the temperature of each wedge. By doing so, they could observe rise and fall of emission from the star’s surface, as the hot spots disappear and appear again while the star rotates. It is also the first time that surface details ranging in size from less than 100 metres to about one kilometre are identified on the surface of objects hundreds to thousands light-years away.

The team think that the hot spots are most probably linked to the polar regions of the neutron stars. This is where the star’s magnetic field funnels charged particles back towards the surface, in a way somehow similar to the ‘Northern lights’, or aurorae, seen at the poles of planets which have magnetic fields, such as Earth, Jupiter and Saturn.

“This result is a first, and a key to understand the internal structure, the dominant role of the magnetic field treading the star interior and its magnetosphere, and the complex phenomenology of neutron stars,” says Patrizia Caraveo, of the Istituto Nazionale di Astrofisica (IASF), Milan, Italy.

“It has been possible only thanks to the new capabilities provided by the ESA XMM-Newton observatory. We look forward to applying our method to many more magnetically isolated neutron stars,” concludes Caraveo.

However, there is still a puzzle for the astronomers. If the three ‘musketeers’ are predicted to have polar caps of comparable dimensions, why then are the hot spots observed in the three cases so different in size, ranging from 60 metres to one kilometre? What mechanisms rule the difference? Or does this mean some of the current predictions on neutron stars magnetic fields need to be revised?

The result, by Andrea De Luca, Patrizia Caraveo, Sandro Mereghetti, Matteo Negroni (IASF) and Giovanni Bignami of CESR, Toulouse and University of Pavia, is published in the 20 April 05 issue of the Astrophysical Journal (http://www.journals.uchicago.edu/ApJ, vol. 623:1051-1069).

Norbert Schartel | EurekAlert!
Further information:
http://www.esa.int/esaCP/SEMLY9NQS7E_index_0.html
http://www.sciops.esa.int

More articles from Physics and Astronomy:

nachricht NASA mission surfs through waves in space to understand space weather
25.07.2017 | NASA/Goddard Space Flight Center

nachricht A new level of magnetic saturation
25.07.2017 | Georg-August-Universität Göttingen

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>