Magnetic Mega-Star Attracts Scientists

Nadine Northway

A giant magnetic star has been spotted about 20,000 light-years away from Earth in a constellation called Perseus.

This star is called NGC 1624-2, and it is about 35 times the Sun’s mass. This means it has a lot of fuel and it will be bright and hot, making it burn out after about 5 million years. This is about 1 percent of the Sun’s current age at midlife, so its lifespan will not be relatively long.

It is the most magnetic star found yet, and it is carrying with it a large amount of trapped particles. It can help find out about magnetism in stars and the evolution of stars and galaxies.

According to writer Charles Q. Choi, “this massive star possesses a magnetic field of 20,000 times stronger than the sun’s and nearly 10 times stronger than that detected around any other high-mass star.” Magnetic fields that are this strong are very rare and usually are only found in stars with much lower mass.

The magnetic field of this star is 11.4 times the star’s radius and it controls the wind of energetic particles streaming from NGC 1624-2. An astronomer from the Royal Military College of Canada, Greg 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.”

NGC 1624-2 is the most magnetic star known to man, however some mid-mass stars have magnetic fields about twice as strong. Our sun is a low mass star with a high magnetic field. Along with that, some dense remnants of dead stars called magnetars are often seen as the universe’s most magnetic objects.

A typical magnetar might have a magnetic field of about 500 million times larger, according to Wade. However, the flux, or strength of the magnetic field times the surface area of the star, of NGC 1624-2 is almost 700 times larger than your average magnetar.

The discovery of this star can be a very important step to learning about the fundamental processes that produce the magnetic fields of massive stars. The star is very distant though, and studying its light in detail requires monitoring the star with an immense light-gathering powered telescope.

To do this, the international team of scientists used the Hobby-Eberly Telescope at the University of Texas at Austin’s McDonald Observatory, and they found that this star rotates quite slowly. It takes about 160 Earth days to spin once. It takes the Sun about 25 Earth days.

Wade noted that he believes the star is slowed due to having to drag around its wind because it is bound to the magnetic field. “This is something that has to be tested, but it looks very likely,” he said.

They also used the Canada-France-Hawaii Telescope on Hawaii’s Mauna Kea to measure the strength of the star’s magnetic field. They looked specifically at variations in rotation directions of the electromagnetic waves absorbed and emitted by atoms in the magnetic field.

“An excess of clockwise-rotating waves indicates a magnetic field pointing towards us, while an excess of counterclockwise-rotating waves indicates a magnetic field pointing away from us,” Wade said. “The larger the excess, the larger the magnetic field. These excesses are usually very tiny, requiring many observations or careful processing of the data to tease out the signal. But in the case of NGC 1624-2, it was obvious from our very first observations that a remarkably strong magnetic field was present.”

Once they get more information on massive stars, there will be further insight on their galaxies. Wade states, “Magnetism, an essentially invisible phenomenon even to most astronomers, can have extraordinary impact.”

“The most important question we seek to answer is: What is the origin of magnetism in massive stars — where do the fields come from?” Wade said. “We believe this must happen when the stars are very young. It has recently been suggested that stellar collisions and mergers during star formation may be responsible. A major next step is to investigate these early stages of evolution, and in particular to examine the magnetic properties of binary star systems, since these may represent examples of systems that suffered encounters early in their history.”