Modelling extreme magnetic fields and temperature variation on distant
stars

Date:
October 13, 2020
Source:
University of Leeds
Summary:
New research is helping to explain one of the big questions that has
perplexed astrophysicists for the past 30 years - what causes the
changing brightness of distant stars called magnetars. Magnetars
were formed from stellar explosions or supernovae and they have
extremely strong magnetic fields, estimated to be around 100
million, million times greater than the magnetic field found
on earth.



FULL STORY ==========================================================================
New research is helping to explain one of the big questions that has
perplexed astrophysicists for the past 30 years -- what causes the
changing brightness of distant stars called magnetars.


========================================================================== Magnetars were formed from stellar explosions or supernovae and they have extremely strong magnetic fields, estimated to be around 100 million,
million times greater than the magnetic field found on earth.

The magnetic field generates intense heat and x-rays. It is so strong it
also affects the physical properties of matter, most notably the way that
heat is conducted through the crust of the star and across its surface, creating the variations in brightness across the star which has puzzled astrophysicists and astronomers.

A team of scientists -- led by Dr Andrei Igoshev at the University of
Leeds - - has developed a mathematical model that simulates the way the magnetic field disrupts the conventional understanding of heat being distributed uniformly and creates hotter and cooler regions where there
may be a difference in temperature of one million degrees Celsius.

Those hotter and cooler regions emit x-rays of differing intensity --
and it is that variation in x-ray intensity that is observed as changing brightness by space-borne telescopes.

The findings are published today (12 October) in the journal Nature
Astronomy.

The research was funded by the Science and Technology Facilities Council (STFC).



==========================================================================
Dr Igoshev, from the School of Mathematics at Leeds, said: "We see
this constant pattern of hot and cold regions. Our model -- based on
the physics of magnetic fields and the physics of heat -- predicts the
size, location and temperature of these regions -- and in doing so,
helps explain the data captured by satellite telescopes over several
decades and which has left astronomers scratching their heads as to why
the brightness of magnetars seemed to vary.

"Our research involved formulating mathematical equations that describe
how the physics of magnetic fields and heat distribution would behave
under the extreme conditions that exist on these stars.

"To formulate those equations took time but was straightforward. The
big challenge was writing the computer code to solve the equations --
that took more than three years." Once the code was written, it then
took a super-computer to solve the equations, allowing the scientists
to develop their predictive model.

The team used the STFC-funded DiRAC supercomputing facilities at the
University of Leicester.

Dr Igoshev said once the model had been developed, its predictions were
tested against the data collected by space-borne observatories. The
model was correct in ten out of 19 cases.

The magnetars studied as part of the investigation are in the Milky Way
and typically 15 thousand light years away.

The other members of the research team were Professor Rainer Hollerbach,
also from Leeds, Dr Toby Wood, from the University of Newcastle, and Dr Konstantinos N Gourgouliatos, from the University of Patras in Greece.


========================================================================== Story Source: Materials provided by University_of_Leeds. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Andrei P. Igoshev, Rainer Hollerbach, Toby Wood, Konstantinos N.

Gourgouliatos. Strong toroidal magnetic fields required by
quiescent X- ray emission of magnetars. Nature Astronomy, 2020;
DOI: 10.1038/s41550- 020-01220-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201013101641.htm

--- up 7 weeks, 1 day, 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)