Betelgeuse (Alpha Orionis)

Assembled from 18 blocks · 3 evidence · 17 related

1. Story
2. The nearest red supergiant to the Sun and the clearest available example of a massive star in its final phase. Joyce and colleagues (2020) combined asteroseismic, evolutionary and hydrodynamic modelling of its 400-day pulsation to derive a mass of about 16.5 to 19 solar masses, a radius near 764 solar radii and a distance near 168 parsecs - about 548 light-years - and concluded that it is burning helium in its core with on the order of 100,000 years to go. Between October 2019 and March 2020 it faded by more than a magnitude in the visible in the episode known as the Great Dimming; imaging and modelling published in Nature in 2021 attributed it to a dust clump condensing above a cooled patch of the photosphere following a surface mass ejection. In 2025 a probable direct detection of a close stellar companion of roughly 1.5 solar masses was reported from speckle imaging, resolving a long-standing anomaly in its brightness variations. Not a place on Earth.
3. Knowledge
4. Betelgeuse (Alpha Orionis)
5. Red giant and asymptotic giant branch
6. Connections
7. Red giant and asymptotic giant branch
8. Betelgeuse fades by more than a magnitude
9. A close companion to Betelgeuse is probably detected
10. Main sequence (core hydrogen burning)
11. Betelgeuse (Alpha Orionis)
12. Planetary nebula
13. White dwarf
14. Betelgeuse fades by more than a magnitude
15. Evidence
16. Supports a mass of about 16.5-19 solar masses, a radius near 764 solar radii, a distance near 168 parsecs and core helium burning with roughly 100,000 years remaining. All figures come from a search summary of secondary reporting; the paper was not fetched and the distance remains uncertain at roughly the ten-per-cent level.
17. Attributes the 2019-2020 Great Dimming to a dust clump condensing above a cooled patch of the photosphere. Journal and volume come from search summaries; the paper was not fetched. Later work, including a 2022 Astrophysical Journal paper describing a surface mass ejection and 2024 tomography, indicates temperature drop and dust extinction contributed in comparable measure.
18. Reports speckle-imaging observations with 'Alopeke on Gemini North in 2020 and 2024 yielding a probable detection of a companion of roughly 1.5 solar masses at the predicted separation and position angle. Title, DOI and arXiv identifier come from publisher and preprint listings via search; neither the paper nor the NOIRLab release could be fetched (both domains blocked). The word "probable" is the authors' own and is retained here.