They are powered by the fusion of hydrogen (H) into helium (He) in their cores, a process that requires temperatures of more than 10 million Kelvin.Īround 90 percent of the stars in the Universe are main-sequence stars, including our sun. 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 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. The Birth of Star (Video)Ī T Tauri star is a stage in a star’s formation and evolution right before it becomes a main-sequence star. Over time, gravity and pressure increase, forcing the protostar to collapse down.Īll of the energy released by the protostar comes only from the heating caused by the gravitational energy – nuclear fusion reactions haven’t started yet. 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. Here is some information about each type of known star in our universe.īelow, is a simple star color temperature chart that provides examples of some of the most well-known stars in the night sky, and their colors.Ī protostar is what you have before a star forms. Red dwarfs include the smallest of the stars in the Universe, weighing between 7.5% and 50% the mass of the Sun.Īlthough main-sequence Red dwarfs are the most common stars in the universe, there are 7 main types of stars in total. The closest star to Earth ( Proxima Centauri), is a Red dwarf. Red dwarfs burn slowly, meaning they can live for a long time, relative to other star types. In fact, most of the main-sequence Red dwarfs are too dim to be seen with our naked eye from Earth. Our own Sun is a main-sequence, G-type star, but most of the stars in the Universe are much cooler and have low mass. However, main-sequence Red dwarf stars are the most common kind of stars in our Universe. When you look up the night sky on a clear night, it may seem as if most stars are cool, blue stars that would fall under the B, or A class of stars. The system was introduced by William Wilson Morgan and Philip C Keenan in 1943. The Morgan-Keenan (MK) system is used in modern astronomy a classification system to organize stars according to their spectral type and luminosity class. This system is referred to as the Morgan Keenan system. The classification of Stars ( Atlas of the Universe). This diagram shows the typical properties for each type of star. Stars just like our own Sun that burn hydrogen into helium to produce energy. The diagram below shows most of the major types of stars (the majority of stars are main sequence stars). The size and color of a star depend on its age and life-cycle stage. The photo below is of my favorite examples (The Cocoon Nebula), as this deep-sky object is surrounded by countless stars of varying temperatures in the constellation Cygnus.Ĭolorful Stars surrounding the Cocoon Nebula in Cygnus.īeauty aside, there are fascinating underlying reasons why stars have different colors in the night sky. Through astrophotography, I can personally enjoy seeing the many different types of stars in the Universe. You’ll notice that some stars have a warm, orange appearance (such as Betelgeuse in the constellation Orion), and others have a cool, white appearance (like Vega in the constellation Lyra). Although there are scientific reasons why stars are different colors and sizes, everyone can enjoy this reality by simply looking up at the night sky.
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