Massive binary star with magnetic fields discovered

Scientists have discovered the first massive binary star, epsilon Lupi, in which both stars have magnetic fields.

A binary star is a star system consisting of two or more stars, orbiting around their common centre of mass.

"The origin of magnetism amongst massive stars is something of a mystery and this discovery may help to shed some light on the question of why these stars have magnetic fields," said one of the researchers Matt Shultz from Queen's University in Ontario, Canada.

The research showed the strengths of the magnetic fields are similar in the two stars, however, their magnetic axes are anti-aligned, with the south pole of one star pointing in approximately the same direction as the north pole of the other.

"We are not sure why that is yet, but it probably points to something significant about how the stars are interacting with one another. We will need to collect more data," Shultz noted.

Two explanations have been proposed for the origin of massive star magnetic fields, both variants on the idea of a so-called "fossil" magnetic field, which is generated at some point in the star's past and then locked in to the star's outer portion.

The first hypothesis is that the magnetic field is generated while the star is being formed; the second is that the magnetic field originates in dynamos driven by the violent mixing of stellar plasma when the two stars in a close binary merge.

The research was published in the journal Monthly Notices of the Royal Astronomical Society.