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Current Affairs

Supergiant star Betelgeuse

Date: 18 February 2020 Tags: Space

Issue

Using the European Space Organisation’s (ESO) Very Large Telescope (VLT), astronomers have noticed the unprecedented dimming of Betelgeuse, a red supergiant star in the constellation Orion.

 

Background

A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around 5,000 K or lower.

 

Details

  • What has intrigued some astronomers is the fact that along with the dimming, the star’s shape has been changing as well. Instead of appearing round, the star now appears to be “squashed into an ova”.

  • Betelgeuse was born as a supermassive star millions of years ago and has been dramatically and mysteriously dimming for the last six months.

  • The report suggests that while Betelgeuse’s behaviour is out of the ordinary, it doesn’t mean that an eruption is imminent since astronomers predict the star to blast sometime (supernova explosion) in the next 100,000 years or so.

  • Astronomers do not think that Betelgeuse is dimming because it is going to explode. They have other hypotheses that may explain the reasons for Betelgeuse’s change in shape and dimming.

  • The two scenarios are a cooling of the surface due to exceptional stellar activity or dust ejection towards us.

Supernova

  • A supernova is a powerful and luminous stellar explosion. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion.

  • The original object, called the progenitor, either collapses to a neutron star or black hole, or it is completely destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy, before fading over several weeks or months.

  • Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star; or the sudden gravitational collapse of a massive star's core.