![]() ![]() ![]() Stars take millions of years to evolve from one stage to the next, which means that it is impossible for scientists to observe the life of a single star. In comparison, our Sun will spend about 10 billion years on the main sequence before it runs out of fuel and expands into a red giant. They burn through their supply of fuel faster due to higher core temperatures. The most massive stars live the shortest lives. High-mass stars like Alnilam, Alnitak and Mintaka in Orion’s Belt live very short lives, a few million years, while low-mass red dwarfs like Proxima Centauri can spend trillions of years on the main sequence. Stellar mass determines the life stages of a star and how quickly the star goes through them. The systematic process of change that every star undergoes can take a few million years or trillions of years, depending on the star’s mass. Stellar evolution is a process by which a star changes in structure and composition over time. Image: NASA Goddard Space Flight Center, cmglee at Wikimedia Commons (CC BY-SA 4.0) Stellar evolution Life cycles of low-mass (left cycle) and high-mass (right cycle) stars, with examples in italics. These objects are still hypothetical because the universe is not old enough for any stellar remnant to have reached this stage. They will ultimately become cool and dark compact stars. As they radiate away the heat, they lose energy and cool off, but their structure can remain the same virtually forever regardless of temperature. At this point, the star collapses under its own gravity and becomes a compact star (stellar remnant).Ĭompact stars do not produce energy themselves, but other than black holes, they radiate excess heat left from the process of collapse. When they run out of fuel, they evolve away from the main sequence and begin to expand into giants and supergiants.Ī star reaches the end of its life when the outward radiation pressure resulting from the nuclear fusion processes in its core is no longer able to resist the gravitational forces. Massive stars are hotter and they burn through their supply of hydrogen fuel faster. The more massive a star is the shorter its lifespan. It ends when the star becomes a stellar remnant: a white dwarf, neutron star, or black hole.Ī star’s life is primarily determined by its initial mass. It begins when a molecular cloud collapses under its own gravity and begins to contract, heat up, and break up into smaller fragments that give birth to the young star. The spectral type "M" can be further subdivided into grades of temperarute, using the numbers zero to nine, or hottest to coolest.The life cycle of a star is the process of change that every star undergoes over time. The Universe hasn't been in existence long enough for any red dwarfs to have reached an advanced evolutionary state. It is thought that they will remain within the main-sequence for several trillion years. ![]() They can outlive a yellow dwarf such as our Sun by many factors. At most, they can be half the size of the Sun, but they can be as small as one-tenth. Our nearest stellar neighbour, Proxima Centauri, is a red dwarf.Īs well as being dim, they are quite small. Indeed, they are thought to comprise three-quarters of the total stars in the Milky Way Galaxy. They're quite dim, due to their low temperature, but observations have determined that they are extremely abundant in the Universe. As you can see from the above image, far from being red, these stellar objects are more of a dirty orange colour. The phrase "red dwarf" is quite famous, of course, due to the celebrated sit-com of the same name. ![]()
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