Betelgeuse unusual dimming - what's up?

  • Context: High School 
  • Thread starter Thread starter Astronuc
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Discussion Overview

The discussion centers around the recent unusual dimming of Betelgeuse, a red supergiant star, and its potential implications regarding supernova events. Participants explore the star's brightness variations, historical context of supernova observations, and the relationship between Betelgeuse's dimming and the likelihood of an imminent explosion.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants note that Betelgeuse has been dimming significantly, reaching a modern low, and discuss its quasi-periodic brightness variations.
  • Others argue that there is no established link between the current dimming and an impending supernova, emphasizing that astronomers do not believe it is "about to explode" on human timescales.
  • A participant mentions that Betelgeuse's brightness may increase again in the near future, suggesting its variability is a long-standing characteristic.
  • Some contributions highlight the historical context of supernova observations in the Milky Way, noting the last confirmed event occurred in 1604, and that Betelgeuse is not the only candidate for future supernovae.
  • A speculative analogy is made comparing the cycles of a star's radius to an explosive event, suggesting that understanding these cycles might provide insights into the timing of a potential collapse.
  • Participants express interest in the broader implications of Betelgeuse's behavior, including its potential to yield new insights into stellar evolution and supernova progenitors.

Areas of Agreement / Disagreement

Participants generally disagree on the relationship between Betelgeuse's dimming and the likelihood of a supernova occurring soon. While some see the dimming as noteworthy, others assert that it does not indicate an imminent explosion, leading to multiple competing views on the topic.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the relationship between brightness variations and supernova predictions, as well as the dependence on definitions of "soon" in astronomical terms.

Who May Find This Useful

Astronomy enthusiasts, students of stellar evolution, and those interested in supernova phenomena may find this discussion relevant and engaging.

  • #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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