Big Discovery Close to Home

I see so many amazing discoveries from educational institutions around the world, as they do cutting edge research in a variety of space-related fields.  But I am truly excited when a discovery is made close to home, at a university here in Ontario, Canada.  A PhD candidate from Queen’s University named Matt Schultz has discovered the first ever massive binary star in which both stars have magnetic fields, a star called epsilon Lupi.

The polarity of the star’s surface magnetic field, north or south, is indicated by red and blue respectively. Yellow lines indicate the magnetic field lines running from the stellar surfaces. Credit: Visualisation courtesy of Volkmar Holzwarth, KIS, Freiburg

Why is this a big deal? Well if you’ve done a bit of astronomy in school, you’ll know that stars like the Sun have huge magnetic fields.  This is due to convection currents in the Sun’s plasma moving charged particles.  In massive stars however, there is no convection in the outer layers.  Yet massive stars still have magnetic fields.  So where are they coming from?

“The origin of magnetism amongst massive stars is something of a mystery,” says Shultz, “and this discovery may help to shed some light on the question of why these stars have magnetic fields.”

There are currently two ideas for why a massive star has a magnetic field.  The first is that at some time in the star’s past, it had a magnetic field that become ‘locked in’ as the star grew.  The second is that the binary stars are interacting in a way that a magnetic dynamo is being created as they share plasma from a close orbit.

“This discovery doesn’t change the basic statistics that the BinaMIcS collaboration has assembled,” says Shultz, “and we still don’t know why there are so few magnetic, massive stars in close binaries.”

The other interesting fact to point out is that the stars have opposite magnetic polarity, which could mean that the stars are interacting in a specific way that is giving rise to the fields.  This discovery, the first of its kind, will allow astronomers to shed more light on these strange systems, and why they have these surprising magnetic fields.



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