Massive star Betelguese of the Orion constellation is nearing its end of life, and in the next million years it is expected to explode as a supernova. Like many stars of similar size entering their twilight, it is anticipated to eject much of its mass out into outer space at this point.
The problem, according to astrophysicists, is that Betelguese’s upper atmosphere was found much cooler than expected, making it lack the energy to expel gas out of its gravitational pull and into space.
Using the U.S.-German Stratospheric Observatory for Infrared Astronomy (SOFIA), Graham Harper of University of Colorado Boulder and his colleagues took the red giant’s temperature and discovered the issue at hand.
“This challenges all our theoretical models,” he proclaimed at the 227th meeting of the American Astronomical Society last Jan. 7.
Betelguese, which is about 20 times the Sun’s mass, will balloon to an enormous size and start shedding gas. In a few million years it will lose around a quarter of this mass.
But where is it getting the energy to accomplish that when, according to Harper, “the fundamental physics is way off”? The SOFIA data showing it’s as cool as 540 Kelvin – a far cry from temperatures of up to 3,500 Kelvin from a 1998 radio study.
Heat is commonly produced in energy exchange and when objects collide. According to the magnetic field theory of red supergiants, the energy that is pushing the gas outward would tend to warm it up – observations of Betelguese, however, seemed to demonstrate that this wasn’t the case.
What is occurring in the star’s upper atmosphere appears to rule out magnetic fields as the force behind the shedding, as well as challenges the possibility of shockwaves – or astounding releases of plasma ejected from inside – driving its pulsations.
“So it might be it’s a combination of all sorts of things and it’s just somehow fooling us in a very bad way, said Harper.
At the meeting, other studies highlighted the instability of Betelguese, such as its light fluctuating in cycles of up to many years.
At 600 light years away, Betelguese remains one of the closest red giants around. Failing to understand its physics, Harper feared, can make scientists struggle to understand other red giants present in the big, wide universe.