The mystery surrounding the dramatic dimming of red supergiant Betelgeuse, observed over a period of several weeks back in winter 2019, has finally been resolved. In astronomy circles this event is now known as Betelgeuse’s Great Dimming.
A paper published in Nature by a team based at the VLT (Very Large Telescope) has concluded that one part of Betelgeuse underwent a temporary convective cooling process on part of its photosphere, allowing a previously ejected cloud of stellar plasma to condense into a kind of opaque nebulosity, obscuring some of the light from the star over a period of time.
Enormous stars like Betelgeuse have highly turbulent and dynamic surfaces and this event has helped us better understand the periodic mass loss that red supergiants experience in their last stages of evolution, as they literally ‘puff away’ vast swathes of their extended atmosphere into space.
It’s fair to say we’re still at the very earliest stages of truly understanding the complex processes controlling these dying stars.
I feel very privileged and humbled to have witnessed this exciting event (with others) from the surface of a tiny world over 550 light years away, and by extension 550 years after it actually happened.
Amazing visualisation of a star captured and ripped apart by the immense gravitational well of a Black Hole.
As the outer atmosphere of the star is accelerated by the black hole’s gravity much of it reaches escape velocity and is strewn into space, while some becomes trapped in a highly eccentric orbit. Stellar material reaching the event horizon closer to the back hole is super heated by frictional heating and turbulent flow, generating a bright accretion disk.
Meanwhile jets of concentrated electromagnetic radiation and ionised particles are blasted deep into space along the axis of rotation – a so called astrophysical jet. This transfer of kinetic energy means the black hole system is slowly loosing angular momentum over time.
I often think the universe at this scale is like witnessing a vast machine running on the conservational of energy. A wonderful illustration of the exchange of gravitational potential, angular kinetic, linear kinetic, heat and mass energy.
All energy was created at the big bang singularity and all physical processes from star birth, star death, black holes and even organic human life is the transfer and redistribution of this original energy state.
Safety: Please remember to never observe the Sun without proper eye protection. Solar glasses are needed to observe naked eye and proper objective mounted filters or projection should be used to observe it in binoculars or telescope.
Congratulations to Prof. Catherine Heymans, who’s been appointed Scotland’s 11th Astronomer Royal.
She replaces John Brown who sadly passed away in 2019.
An expert on dark energy and dark matter, Catherine is also director of the German Centre for Cosmological Lensing at Ruhr-University Bochum.
One of Catherine’s most exciting early initiatives in the role will be to install telescopes in all of Scotland’s remote outdoor learning centres, that are visited by school pupils.
She’s passionate about the cathartic experience of live observing, and how this can drive a lifelong passion for science:
“I don’t think anyone forgets the first time they saw the rings of Saturn through a telescope, but too many people never have the chance.“
“My hope is that once that spark and connection with the universe is made, children will carry that excitement home with them and develop a life-long passion for astronomy or, even better, science as a whole,”.
I couldn’t agree more.
The position of Astronomer Royal for Scotland was created in 1834 and originally held by the director of the Royal Observatory, Edinburgh.
Jocelyn Bell Burnell, president of the Royal Society of Edinburgh, said: “The Astronomer Royal for Scotland has always been a distinguished and respected astronomer, and Professor Heymans is exactly that.”