Astronomers have determined after studying data from Nasa's Hubble Space Telescope and a number of other observatories that the bright red supergiant star Betelgeuse essentially blew its top in 2019, losing a significant portion of its visible surface and creating a massive ‘surface mass ejection’ (SME). “This is something never before seen in a normal star's behaviour,” according to a statement on Nasa's website.
The star Betelgeuse is a brilliant, ruby-red, twinkling spot of light in the upper right shoulder of the winter constellation Orion the Hunter. But when viewed up close, "astronomers know it as a seething monster with a 400-day-long heartbeat of regular pulsations," according to Nasa's Hubblesite. This ageing star is a supergiant because of its astounding expansion to a diameter of almost 1 billion miles. “If placed at the centre of our solar system it would reach out to the orbit of Jupiter.”
Also read: Scientists have found the heaviest known neutron star
In a phenomenon known as a ‘coronal mass ejection’ (CME), our sun periodically throws out portions of its flimsy outer atmosphere – the corona – as well. However, the Betelgeuse SME ejected 400 billion times more mass than an average CME.
A convective plume that was boiling up from the star's interior may have been the origin of the colossal outburst in 2019. It produced shocks and pulsations that blasted off the chunk of the photosphere leaving the star with a large cool surface area under the dust cloud that was produced by the cooling piece of photosphere. Betelgeuse is now struggling to recover from this injury, the Nasa website adds.
The fragmented photosphere, which was roughly several times as heavy as our Moon, flew off into space, cooled, and formed a dust cloud that obscured the star from Earth-based observers.
The Tillinghast Reflector Echelle Spectrograph (TRES) at Fred L. Whipple Observatory and NASA's Hubble reveal that although Betelgeuse's outer layers appear to be returning to normal, the surface is still bouncing like a dish of gelatin pudding as the photosphere regenerates.
Also read: Scientists discover a super-Earth 37 light years from us
Even more astounding, the supergiant's 400-day pulsation rate is now gone, at least temporarily. For the past 200 years, scientists have measured this rhythm which plays a key role in determining the ferocity of the final blowout.
These new discoveries provide information on how red stars lose mass toward the end of their lives when their nuclear fusion furnaces exhaust, leading to their eventual explosion as supernovae. Their eventual explosions are highly impacted by the mass loss. Betelgeuse's unusually obnoxious conduct is hardly a sign that the star is poised to explode any time soon either.
A supergiant 724 light years from us, Betelgeuse's eventual fate is to blow up as a supernova and when it does, it will briefly be visible in Earth's daytime sky.
Also read: Do supermassive black holes influence how stars are formed?