TNRTB Archive - Retained for reference information
Astronomers discover that spots on the surface of stars, even stars of the same mass as the sun, can attain such large sizes that they generate large and rapid variations in the star’s luminosity. Since such variability is detrimental to life, minimal star spot activity is a requirement for habitability.
Sarah Tackett, William Herbst, and Eric Williams, “Periodic Variability in the Pre-Main Sequence Object CB 34V,” Astronomical Journal, 126 (2003), pp. 346-352.
RTB video: Journey Toward Creation, 2nd edition
RTB book: The Creator and the Cosmos, third edition