 The luminosity of a supernova depends on the mass of the star. If we knew the mass, we'd have ourselves another standard candle. But for most explosions across the cosmos, we don't have that information. But there is one scenario where we do. It's called a Type 1A supernova. It is based on a particular binary star setup, and it is recognizable by a light profiles and spectral analysis. Here's how it works. 1. A massive red giant star has a small stellar companion. 2. Mass flows from the giant to the dwarf through the L1 Lagrange point. You'll remember Lagrange points from our discussion on Jupiter in this segment on our solar system. 3. The mass of the dwarf star increases. And 4. Once the mass of the smaller star reaches a critical level, its ability to hold off collapsing under the force of gravity comes to an end. The result is a total collapse inside a few seconds. This creates a supernova explosion that rips the smaller star into pieces. Type 1A supernova provide a candle as accurate as C-fied variables, but with the advantage that they can be seen clearly at much larger distances.