This movie shows the evolution of a star as massive as our sun. Each star spends most of its life in a phase known as the main sequence, during which it burns hydrogen into helium at its center and it slowly expands (as the reference circles show) to accommodate the energy produced via this nuclear fusion. The expansion causes the surface temperature to decrease, bringing the color of the star towards the red part of the electromagnetic spectrum.
Credit: Stellar simulation by Vicky Kalogera, Bart Willems and Francesca Valsecchi. Visualization by Matthew McCrory. / Funding: NSF and LIGO