Betelgeuse unusual dimming - what's up?

  • Context: High School 
  • Thread starter Thread starter Astronuc
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SUMMARY

Betelgeuse, a red supergiant star, is currently experiencing significant dimming, reaching a modern all-time low of V = +1.12 mag as of December 7, 2019. This dimming has been attributed to complex pulsations and the behavior of large super-granules on its convective surface, rather than an imminent supernova event. Astronomers E.F. Guinan, R.J. Wasatonic, and T.J. Calderwood have conducted extensive photometric observations over the last 25 years, revealing quasi-periodic brightness variations with a dominant cycle of approximately 420 days. Despite speculation in media about a potential supernova, experts assert that there is no scientific evidence linking the current dimming to an impending explosion.

PREREQUISITES
  • Understanding of stellar classification, particularly M-type supergiants.
  • Familiarity with photometric measurement techniques in astronomy.
  • Knowledge of supernova types, specifically Type II supernovae and their progenitors.
  • Basic grasp of stellar evolution and the life cycle of massive stars.
NEXT STEPS
  • Research "Betelgeuse light curves" to analyze historical brightness data.
  • Study "supergiant star variability" to understand pulsation mechanisms.
  • Explore "Type II supernova progenitors" to identify other candidates in the Milky Way.
  • Investigate "stellar convection and granulation" to comprehend surface dynamics of red supergiants.
USEFUL FOR

Astronomers, astrophysics students, and anyone interested in stellar evolution and supernova phenomena will benefit from this discussion. It provides insights into the behavior of red supergiants and the implications of their variability.

  • #61
epenguin said:
The scientists have concluded that some time before the great dimming, the star ejected a large gas bubble. When a patch of its surface cooled shortly afterwards, the temperature decrease was enough for heavier elements, such as silicon, that were contained within the gas to condense into solid particles.
This is an interesting piece that's not mentioned in other published summaries. I take the part about "before the great dimming, the star ejected a large gas bubble" to mean something like a CME, but it was still hot and transparent. Then "when a patch of its surface cooled shortly afterwards, the temperature decrease was enough for heavier elements, such as silicon, that were contained within the gas to condense into solid particles." But isn't it the ejected mass that cooled? Or did the outer surface cool?

In either event, cooling such that Si or perhaps SiO2 precipitated and condensed into dust particles, and perhaps Al2O3, or alumina-silicates.

There is this paper "A dusty veil shading Betelgeuse during its Great Dimming"
https://www.nature.com/articles/s41586-021-03546-8
 

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