Stars can theoretically grow to more than 100 times the mass of the Sun. This is the minimum amount of gravitational pressure you need to ignite fusion in the core. The lower mass limit for a main sequence star is about 0.08 times the mass of the Sun, or 80 times the mass of Jupiter. Stars in the main sequence will have a size that depends on their mass, which defines the amount of gravity pulling them inward. The inward and outward forces balance one another out, and the star maintains a spherical shape. Gravity is pulling the star inward, and the light pressure from all the fusion reactions in the star are pushing outward. Main sequence stars can vary in size, mass and brightness, but they’re all doing the same thing: converting hydrogen into helium in their cores, releasing a tremendous amount of energy.Ī star in the main sequence is in a state of hydrostatic equilibrium. Our Sun is a main sequence star, and so are our nearest neighbors, Sirius and Alpha Centauri A. The majority of all stars in our galaxy, and even the Universe, are main sequence stars. Stars will remain in the T Tauri stage for about 100 million years. T Tauri stars can have large areas of sunspot coverage, and have intense X-ray flares and extremely powerful stellar winds. T Tauri stars don’t have enough pressure and temperature at their cores to generate nuclear fusion, but they do resemble main sequence stars they’re about the same temperature but brighter because they’re a larger. This phase occurs at the end of the protostar phase, when the gravitational pressure holding the star together is the source of all its energy. Credit: T Tauri Star:Ī T Tauri star is stage in a star’s formation and evolution right before it becomes a main sequence star. Size chart showing our Sun (far left) compared to larger stars. All of the energy release by the protostar comes only from the heating caused by the gravitational energy – nuclear fusion reactions haven’t started yet. Over time, gravity and pressure increase, forcing the protostar to collapse down. The protostar phase of stellar evolution lasts about 100,000 years. A protostar is a collection of gas that has collapsed down from a giant molecular cloud. Protostar:Ī protostar is what you have before a star forms.
Let’s take a look at all the different types of stars there are. And as our exploration of the Universe continues, we continue to learn things about stars that force us to expand on the way we think of them. There are even more bizarre kinds of stars, like neutron stars and Wolf-Rayet stars. In truth, stars are about as diverse as anything else in our Universe, falling into one of many different classifications based on its defining characteristics.Īll in all, there are many different types of stars, ranging from tiny brown dwarfs to red and blue supergiants. But they are all basically the same, big balls of gas burning up to billions of light years away, right? Well, not exactly. A star is a star, right? Sure there are some difference in terms of color when you look up at the night sky.