Surprise! The biggest, most massive stars aren’t always the hottest.
To first become a star, your core must cross a critical temperature threshold: ~4,000,000 K.
Such temperatures are required to initiate core fusion of hydrogen into helium.
However, the surrounding layers diffuse heat, capping photosphere temperatures at ~50,000 K.
Higher temperatures require additional evolutionary steps.
Your star’s core contracts and heats up upon exhausting its hydrogen.
Helium fusion then begins, injecting even more energy.
However, “red giant” stars are quite cool, expanding to lower their surface temperatures.
Most red giants blow their outer layers away, revealing a heated, contracted core.
With white dwarf surfaces reaching ~150,000 K, they surpass even blue supergiants.
The highest stellar temperatures, however, are achieved by Wolf-Rayet stars.
Destined for cataclysmic supernovae, Wolf-Rayet stars are fusing the heaviest elements.
They’re highly evolved, luminous, and surrounded by ejecta.
The hottest one measures ~210,000 K; the hottest “true” star.
The remnant cores of supernovae can form neutron stars: the hottest objects of all.
With initial interior temperatures cresting ~1 trillion K, they radiate heat quickly.
After mere years, their surfaces cool to ~600,000 K.
Despite all we’ve discovered, neutron stars remain the hottest and densest singularity-free objects known.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.