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Colliding neutron stars produce the strongest magnetic fields inthe Universe (Forwarded)



 
 
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Old April 3rd 06, 03:23 PM posted to sci.space.news
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Default Colliding neutron stars produce the strongest magnetic fields inthe Universe (Forwarded)

ROYAL ASTRONOMICAL SOCIETY PRESS NOTICE

Issued by: RAS Communications Officers

Anita Heward
Tel: +44 (0)1483-420904

Peter Bond
Tel: +44 (0)1483-268672 Fax: +44 (0)1483-274047

National Astronomy Meeting Press Room (4 - 7 April only):
Tel: +44 (0)116-229-7474 or 229-7475 or 252-3312 or 252-3531
Fax: +44 (0)116-252-3531

RAS Web site: http://www.ras.org.uk/

RAS NATIONAL ASTRONOMY MEETING 2006
THE UNIVERSITY OF LEICESTER
TUESDAY 4 APRIL TO FRIDAY 7 APRIL
CONTACT DETAILS ARE LISTED AT THE END OF THIS RELEASE.

EMBARGOED FOR 2:00 PM U.S. EASTERN TIME (8:00PM BST) THURSDAY, 30 MARCH
2006.

Ref. PN 06/09 (NAM 3)

COLLIDING NEUTRON STARS PRODUCE THE STRONGEST MAGNETIC FIELDS IN THE
UNIVERSE

The first computer simulation to model the collision of two magnetised
neutron stars shows that the impact generates the strongest magnetic
fields known in the Universe. The gigantic fields are more than a thousand
million million times stronger than the magnetic field of the Earth and
are thought to launch the violent gamma-ray burst explosions.

Neutron stars have masses comparable to that of our Sun, but a radius of
only 10 km, so they are even denser than atomic nuclei. Neutron stars that
orbit around each other in binary systems will, according to Einsteins
Theory of General Relativity, slowly spiral in towards each other. Their
final fate is a thunderously violent collision.

The results of simulations of these collisions are being presented at the
Royal Astronomical Society's National Astronomy Meeting on 5th April and
at the Ringberg-conference on Nuclear Astrophysics on the 7th April. They
are published in the online journal Science Express on 30th March.

Dr. Daniel Price from the University of Exeter, UK, said: "It is only
recently that we have the computing power available to model the
collisions and take into account the effects of magnetic fields. It has
taken us months of nearly day and night programming to get this project
running." Prof. Stephan Rosswog from the International University of
Bremen, Germany, adds: "This is an incredible result. Magnetic fields that
we are familiar with, say from a magnet at your refrigerator, have
strength of about 100 Gauss. Such a collision produces field that are an
incredible 10 million million times stronger."

In the supercomputer simulations, Price and Rosswog show that within the
first millisecond of the collision, magnetic fields are produced that are
stronger than any other magnetic field that is known in the Universe. The
calculations are a computational challenge because they include a lot of
exotic physics, including effects of high-density nuclear physics,
particle physics and General Theory of Relativity. To calculate only a few
milliseconds of a single collision takes several weeks on a parallel
supercomputer.

It has long been suspected that such a collision may be at the heart of
some of the brightest explosions in the Universe since the Big Bang,
so-called short gamma-ray bursts. Recent detections of 'afterglows' of
such bursts have confirmed this idea, but much of the physics behind these
explosions lies still in the dark.

NOTES FOR EDITORS:

The 2006 RAS National Astronomy Meeting is hosted by the University of
Leicester and sponsored by the Royal Astronomical and the UK Particle
Physics and Astronomy Research Council (PPARC).
For further information see:
http://www.nam2006.le.ac.uk/

The 13th Workshop on Nuclear Astrophysics, held at the Ringberg Castle,
will bring together astrophysicists, nuclear physicists, and
astro-particle physicists in order to discuss topics of common
astrophysical interest. The workshop is organised by the Max Planck
Institut fur Astrophysik.
For further information see:
http://www.mpa-garching.mpg.de/Hydro.../workshop.html

Science Express:
http://www.sciencemag.org/cgi/conten...ract/1125201v1

Images

For animations and stills from the supercomputer simulation, see:
http://www.astro.ex.ac.uk/people/dprice/research/nsmag/

Image Captions:

[1125102cover.jpg]
A snapshot from the coalescence of two magnetized neutron stars, showing
magnetic field strengths in the material at and below the orbital plane.
Blue corresponds to the unamplified magnetic field whilst yellow/white
indicates material with magnetic field strengths higher than even those
found in magnetars. The two stars have merged together in just a few
milliseconds, shedding mass into spiral arms that are subsequently wrapped
around the central object to form a hot torus. The magnetic field is
amplified in the shear instability between the stars which is clearly
visible in the central regions. The snapshot shows the configuration ~4
milliseconds after the merger and dimensions are ~140 km from left to
right.

[1125201panels_clean.jpg and 1125201panels_nocolourbar.jpg]
Snapshots (left to right, top to bottom) of the coalescence of two
magnetised neutron stars, showing magnetic field strengths in the material
at and below the orbital plane. Dimensions in each panel are ~140 km from
left to right. The stars move gradually towards each other and then merge
in a "plunging phase" within about one orbital period (~2 ms; first two
snapshots). This object sheds mass into spiral arms that are subsequently
wrapped around the central object (snapshots three to five) to form a hot
torus (last snapshot). The magnetic field is amplified in the shear
instability between the stars and subsequently advected with the matter to
cover the surface of the central merger remnant.

[1125201fullstars.jpg]
A snapshot from the coalescence of two magnetized neutron stars, showing
magnetic field strengths in the material at the surface of the merged
object: Blue corresponds to the unamplified magnetic field whilst
yellow/white indicates material with magnetic field strengths higher than
even those found in magnetars. The two stars have merged together in just
a few milliseconds, shedding mass into spiral arms that are subsequently
wrapped around the central object to form a hot torus. The snapshot shows
the configuration ~4 milliseconds after the merger and dimensions are ~140
km from left to right.

Image Credits: Daniel Price and Stephan Rosswog.

CONTACT:

Dr. Daniel Price
Schoolof Physics, University of Exeter
Stocker Rd, Exeter EX4 4QL, UK
Phone: +44 1392 264138
Fax: +44 1392 264111
Web : http://www.astro.ex.ac.uk/people/dprice/

Dr. Stephan Rosswog
Professor of Astrophysics, International University Bremen
School of Engineering and Science, International University Bremen
Campusring 1, 28759 Bremen, Germany
Phone: +49 421 200 3226
Fax: +49 421 200 3229
Web: http://www.faculty.iu-bremen.de/srosswog


 




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