How long main sequence star

The brightness is measured in magnitude, the brighter the star the lower the magnitude goes down. There are two ways to measuring the brightness of a star, apparent magnitude is the brghtness seen from Earth, and absolute magnitude which is the brightness of a star seen from a standard distance of 10 parsecs Stars can be plotted on a graph using the Hertzsprung Russell Diagram see picture below.

It shows that the temerature coincides with the luminosity, the hotter the star the higher the luminosity the star has. You can also tell the size of each star from the graph as the higher the radius the higher the temperature and luminosity.

Stage 1- Stars are born in a region of high density Nebula , and condenses into a huge globule of gas and dust and contracts under its own gravity. This image shows the Orion Nebula or M Stage 2 - A region of condensing matter will begin to heat up and start to glow forming Protostars. If a protostar contains enough matter the central temperature reaches 15 million degrees centigrade. Stage 3 - At this temperature, nuclear reactions in which hydrogen fuses to form helium can start.

A planetary nebula is the final stage of a Sun-like star. As such, planetary nebulas allow us a glimpse into the future of our own solar system. A star like our Sun will, at the end of its life, transform into a red giant. Stars are sustained by the nuclear fusion that occurs in their core, which creates energy. This means that even though a red giant is large in terms of linear size, it is less massive than the main sequence star it came from.

Begin typing your search term above and press enter to search. Press ESC to cancel. Skip to content Home Physics How long does a star stay in main sequence? Figure 1: Hydrostatic equilibrium. Life Cycle. Stellar Evolution. Latest Gallery Images. Relative to the Sun, this supergiant has a much larger radius, a much lower average density, a cooler surface, and a much hotter core. Red giants can become so large that if we were to replace the Sun with one of them, its outer atmosphere would extend to the orbit of Mars or even beyond Figure 3.

Figure 3. In the left image, we see it in ultraviolet with the Hubble Space Telescope, in the first direct image ever made of the surface of another star.

As shown by the scale at the bottom, Betelgeuse has an extended atmosphere so large that, if it were at the center of our solar system, it would stretch past the orbit of Jupiter. As we discussed earlier, astronomers can construct computer models of stars with different masses and compositions to see how stars change throughout their lives. Figure 4, which is based on theoretical calculations by University of Illinois astronomer Icko Iben, shows an H—R diagram with several tracks of evolution from the main sequence to the giant stage.

Tracks are shown for stars with different masses from 0. The red line is the initial or zero-age main sequence. The numbers along the tracks indicate the time, in years, required for each star to reach those points in their evolution after leaving the main sequence. Once again, you can see that the more massive a star is, the more quickly it goes through each stage in its life.

Figure 4. Evolutionary Tracks of Stars of Different Masses: The solid black lines show the predicted evolution from the main sequence through the red giant or supergiant stage on the H—R diagram. Each track is labeled with the mass of the star it is describing. The numbers show how many years each star takes to become a giant after leaving the main sequence. The red line is the zero-age main sequence. Note that the most massive star in this diagram has a mass similar to that of Betelgeuse, and so its evolutionary track shows approximately the history of Betelgeuse.

The track for a 1-solar-mass star shows that the Sun is still in the main-sequence phase of evolution, since it is only about 4. When stars first begin to fuse hydrogen to helium, they lie on the zero-age main sequence. The amount of time a star spends in the main-sequence stage depends on its mass.

More massive stars complete each stage of evolution more quickly than lower-mass stars. The fusion of hydrogen to form helium changes the interior composition of a star, which in turn results in changes in its temperature, luminosity, and radius. Eventually, as stars age, they evolve away from the main sequence to become red giants or supergiants.