QUO Fast Radio Bursts

E05: The Dimming Stellar Giant

November 30, 2020 Queen's Observatory Season 1 Episode 6
QUO Fast Radio Bursts
E05: The Dimming Stellar Giant
Show Notes

In Space News:

  • It is was recently decided that the Arecibo Observatory in Puerto Rico is being decommissioned. Read more about it here.
  • Space X crew launched a 6 month manned mission to the ISS.

Now on to the main topic; "The Dimming Stellar Giant -- Betelgeuse."


  • Betelgeuse is a red supergiant about 550 light-years away from us. 
  • It is about 18 times more massive,  760 times wider, and 100,000 brighter than our Sun.
  • Surface temperature is a cool 3600K compared to Sun 5800K. It is 8.0-8.5 Myr old compared to our Sun’s 5 Gyr.
  • Betelgeuse is a variable star (Semi-regular variable star).  The primary pulsations repeat every ~425 days, but the star also shows additional changes in brightness with periods of 100-180 days and 5.9 years, it dims to less than half it's maximum brightness (1 magnitude).

The Dimming Event

  • In late December 2019/ early January 2020, in its expected dimming cycle, Betelgeuse dimmed unusually far (1.3 magnitudes).
  • The unexpected dimming was probably caused by an immense amount of superhot material ejected into space. The material cooled and formed a dust cloud that blocked the starlight coming from about a quarter of Betelgeuse's surface. (Read more about it here)
  • This dimming event re-ignited a conversation about a possible imminent supernova. If Betelgeuse does go supernova, it'll be brighter than the Moon for about two months. It will be a spectacle to watch.