BETELGEUSE - SCI & TECH
News:
Explained | If Betelgeuse goes supernova, what would it look like?
What's in the news?
● The
bright, red star Betelgeuse in the constellation Orion has shown some unexpected behaviour.
Key takeaways:
● In
late 2019 and 2020 it became fainter than we had ever seen it – at least in
records going back more than a century. Briefly it became fainter (just about)
than Bellatrix, the third brightest star of Orion. This event became known as
the “great dimming”.
● But
Betelgeuse has since become bright again. For a few days this year, it was the brightest star in Orion – brighter than
we have ever seen it. Both events led to speculation about whether its demise
in the form of an explosion is imminent.
Betelguese:
● Betelgeuse,
the seventh brightest star in the sky
(discounting the Sun), is the brightest of the variable stars.
● Sometimes
Betelgeuse becomes nearly as bright as Rigel
(the blue fourth brightest star in the constellation), while at other times
it is notably fainter.
● The
variation is caused by pulsations, similar to those of Mira although not as
large or as regular.
Uniqueness of Betelguese:
● Betelgeuse
is about 15 to 20 times more massive
than the Sun, and stars of this mass are expected to end their lives in a
powerful explosion known as a supernova.
● Betelgeuse’s
red colour shows it is a red supergiant, meaning it’s already approaching the
end of its life.
Go back to basics:
Supernovae:
● Sometimes,
a star can briefly become extremely
bright. The brightest and rarest among those are the supernovae, formed
when an entire star ends its life in a
powerful explosion.
● Supernovae
can be bright enough to be visible during the day, although that has only
happened a few times in the past 1,000 years.
Features:
● Supernovae
produce high energy particles called
cosmic rays, which can get past the shield of the earth’s magnetic field.
● A
supernova explosion would also create radioactive
iron. In fact, this substance has been found in the earth’s seabed and on
the Moon, believed to have formed in a supernova explosion between 2 and 3
million years ago.
Challenges of Supernova:
● A
very close supernova, closer than 30 light-years, could cause major problems.
● The
cosmic rays could cause ozone
destruction and dangerous UV levels on the earth.
● It
could reduce ozone by half over a period lasting hundreds to thousands of years
- this level is considered capable of causing an extinction event. (But such a
close supernova would be very rare, and may happen only once per billion years)