119 Tauri (CE Tauri) — a red supergiant in Taurus

Physical characteristics

CE Tauri has one of the largest stellar radii known among naked-eye stars. Estimates put its diameter at more than 590 times that of the Sun — on the order of 8.3×108 kilometres — which makes its size comparable to the orbital radius of Jupiter. As a red supergiant it has a cool surface temperature relative to hot stars, an extended tenuous atmosphere, and high luminosity produced by a massive, evolved core.

Variability and observations

Classified as a variable star, CE Tauri shows changes in brightness and spectral features caused by pulsations, large convective cells and episodic mass loss. Modern instruments, including optical and infrared interferometers, have resolved surface irregularities and measured changes in its apparent diameter over time. Researchers use such direct observations to study convection, atmospheric dynamics and the mechanisms that drive stellar winds in very large stars (interferometric studies).

Because its angular size can be measured, CE Tauri serves as an important laboratory for testing models of stellar structure and late-stage evolution. Photometric and spectroscopic monitoring also help track semi-regular variability and episodic dust production in its surroundings. Observations across different wavelengths reveal layers of gas and dust expelled from the star, contributing to the enrichment of the interstellar medium.

• Naming: Flamsteed number 119 Tauri and variable-star name CE Tauri.
• Type: Red supergiant (cool, luminous, late evolutionary stage).
• Size: Diameter hundreds of times the Sun; comparable to Jupiter's orbital radius.
• Importance: Studied for convection, pulsation, mass loss and pre-supernova evolution (further reading).

Like other red supergiants, CE Tauri is expected eventually to end its life in a core-collapse supernova, though the timing and exact pathway depend on its current mass-loss history and interior structure. For astronomers, continued monitoring and high-resolution imaging keep CE Tauri among the useful nearby examples for understanding how massive stars evolve and return material to space.