The massive magnetosphere around one extremely hot and bright star contains stellar winds and dense plasma capable of consuming X-rays before they can escape into space, new research from astronomers at the Florida Institute of Technology has revealed.
Thanks to observations of the O-type known as NGC 1624-2 made using NASA’s Chandra X-ray Observatory, FIT assistant professor Véronique Petit and her colleagues found that the star has stellar winds three to five times faster and at least 100,000 times more dense than the sun.
NGC 1624-2’s magnetosphere, which is larger than any other star in its class, traps gases trying to escape from the star, and those gases in turn absorb their own X-rays. The stellar winds clash with the magnetic field, and the trapped particles create a large aura of hot, dense plasma around NGC 1624-2, the authors wrote in the Monthly Notices of the Royal Astronomical Society.
Magnetic field rare for stars of this size
“The magnetic field isn’t letting its stellar wind get away from the star,” Petit, a member of the team that originally discovered the star in 2012, explained in a statement. “So you get these big flows that are forced to collide head on at the magnetic equator, creating gas shock-heated to 10 million Kelvin and plenty of X-rays.”
However, she added, “the magnetosphere is so large that nearly 80 percent of these X-rays get absorbed before being able to escape into free space and reach the Chandra telescope.” She and her colleagues hope to gain more information about this unusual star next month, when they are expecting to receive new data on its stellar winds from the Hubble Space Telescope.
The magnetic field found at the surface of NGC 1624-2 is 20,000 times stronger than that found on the surface of our sun, the study authors explained. If this star was at the center of our solar system instead of the sun, the loops of hot, dense plasma it gives off would almost make it all the way to the orbit of the planet Venus, they added.
Just 10 percent of these massive starts have magnetospheres like this. While smaller stars (again, like the sun) have an internal dynamo used to generate magnetic fields, those existing in massive stars are remnants left over from a collision with another star or another event from an earlier point in the life of said star.
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Feature Image: Florida Institute of Technology
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