Betelgeuse

Betelgeuse is a red supergiant star marking Orion’s shoulder. Its enormous size, variable brightness, and advanced evolution make it a prominent nearby candidate for a future supernova.

Red supergiant: A massive star in a late evolutionary phase, with a greatly expanded, relatively cool outer envelope. Betelgeuse is a nearby example of this short-lived stellar phase.
Great Dimming of Betelgeuse: An unusually deep decline in Betelgeuse’s brightness from late 2019 into early 2020. This event drew attention to the star’s variability and changing surface.
Stellar interferometry: An observing technique that combines light from separate telescopes to obtain angular resolution beyond that of each telescope alone. Interferometry resolves Betelgeuse’s disk and reveals structure across its surface.
Rigel: A blue supergiant star in Orion and one of the constellation’s brightest stars. Rigel contrasts with Betelgeuse in color, temperature, and position within Orion.
Stellar evolution: The changes in a star’s structure and energy production over its lifetime. Betelgeuse’s size and variability reflect its advanced evolutionary state.
Hubble Space Telescope: A space observatory launched in 1990 that observes the universe across ultraviolet, visible, and near-infrared wavelengths. Hubble images helped trace material ejected from Betelgeuse during its Great Dimming.
Very Long Baseline Array: A network of radio telescopes across North America that operates as a single interferometer. Radio observations with the array have measured Betelgeuse’s apparent size and changing atmosphere.
Sirius: The brightest star in Earth’s night sky, a nearby binary system in Canis Major. Sirius appears brighter from Earth, though Betelgeuse is vastly larger and more luminous intrinsically.
Stellar pulsation: Periodic expansion and contraction of a star’s outer layers that can change its brightness and size. Pulsations contribute to Betelgeuse’s recurring variations in brightness.
Very Large Telescope: A four-telescope optical and infrared observatory operated by the European Southern Observatory in Chile. Its SPHERE instrument captured detailed images of Betelgeuse during the Great Dimming.

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