Magnatar: massive magnetic star

The most magnetic massive star seen yet is dragging a giant cloak of trapped charged particles around it.

This newly discovered star, NGC 1624-2, could help shed light on what role the magnetism of stars plays in the evolution of stars and their galaxies.

NGC 1624-2, which lies about 20,000 light-years from Earth in the constellation Perseus, has about 35 times the sun's mass.

Its hefty mass gives it plenty of fuel, making it bright and hot and thus likely to burn out relatively quickly after a lifetime of about 5 million years, or one-tenth of 1 percent of the sun's current age at midlife.

This massive star possesses a magnetic field 20,000 times stronger than the sun's and nearly 10 times stronger than that detected around any other high-mass star.

"Magnetic fields of this strength are extremely rare — they are only known to exist in a few other stars of much lower mass," study lead author Gregg Wade, an astronomer at the Royal Military College of Canada, reported.

"To find such a strong field is very lucky." This powerful magnetic field binds and controls the stellar wind of energetic particles streaming from NGC 1624-2 "to a very large distance from the star — 11.4 times the star's radius," Wade said.

"The huge volume of this magnetosphere is remarkable. It's more than four times wider than that of any other comparable massive star, and in terms of volume it is around 80 times larger."

While NGC 1624-2 is the most magnetic of all known massive stars, a few intermediate-mass stars have magnetic fields maybe twice as strong, Wade said.

In addition, as powerful as NGC 1624-2's magnetic field is, it might pale in comparison with that of magnetars – dense remnants of dead stars that are often thought of as the universe's most magnetic objects.

"The magnetic field of NGC 1624-2 is about 20,000 gauss at the star's surface. A typical magnetar might have a field on the order of 10 trillion gauss, so the strength of the magnetar's field is much larger — that is, 500 million times larger," Wade said.

However, "the standard basis for comparison of how 'much' magnetic field is present is the magnetic flux, which is equal to the strength of the magnetic field times the surface area of the star," Wade said.

"In that case, the flux of NGC 1624-2 is almost 700 times larger than that of a typical magnetar. "In other words, if NGC 1624-2 were to suddenly collapse to the size of a magnetar while retaining all of its magnetism, it would have a surface magnetic field of nearly 10,000 trillion gauss. Holy cow!"