#Night sea of stars series

What happens next depends on how the mass of the star. The star expands to larger than it has ever been a few hundred times bigger! At this point the star is called a red giant. While the core collapses, the outer layers of material in the star to expand outward. Its inner layers start to collapse, which squishes the core, increasing the pressure and temperature in the core of the star. When that happens, the star can no longer hold up against gravity. However, a more massive star uses its fuel faster, and may only be on the main sequence for millions of years.Įventually the core of the star runs out of hydrogen. Our sun will spend about 10 billion years on the main sequence. This is also the longest phase of a star's life. The radiation and heat from this reaction keep the force of gravity from collapsing the star during this phase of the star's life. Stars on the main sequence are those that are fusing hydrogen into helium in their cores. When the protostar starts fusing hydrogen, it enters the 'main sequence' phase of its life. It needs to be 15 million Kelvin in the core for fusion to begin. At some point, it will be hot enough and dense enough for hydrogen to start fusing into helium. This is why these clouds of material are often called stellar nuseries they are places where many stars form.Īs the protostar gains mass, its core gets hotter and more dense. The cloud doesn't collapse into just one large star, but different knots of material will each become it's own protostar. That hot core is called a protostar and will eventually become a star. As the knot collapses, the material at the center begins to heat up. Turbulence within the cloud causes knots to form which can then collapse under it's own gravitational attraction. These clouds are clouds that form between the stars and consist primarily of molecular gas and dust. (Credit: NASA/ESA/Hubble Heritage Team)Īll stars begin their lives from the collapse of material in a giant molecular cloud. Hubble image of the Eagle Nebula, a stellar nursery.

The fate and life of a star depends primarily on it's mass. Using observations of stars in all phases of their lives, astronomers have constructed a lifecycle that all stars appear to go through.

Stellar EvolutionĪ star is born, lives, and dies, much like everything else in nature. However, eventually these reactions will no longer generate sufficient heat to support the star agains its own gravity and the star will collapse.

#Night sea of stars series

If the star is large enough, it can go through a series of less-efficient nuclear reactions to produce internal heat. When the star runs out of nuclear fuel, it comes to the end of its time on the main sequence. So, until it reaches the main sequence, hydrostatic support is provided by the heat generated from the contraction.Īt some point, the star will run out of material in its core for those nuclear reactions. This phase of the star's life is called the main sequence.īefore a star reaches the main sequence, the star is contracting and its core is not yet hot or dense enough to begin nuclear reactions. (Credit: NASA and the Night Sky Network)ĭuring most a star's lifetime, the interior heat and radiation is provided by nuclear reactions in the star's core. Diagram showing the lifecycles of Sun-like and massive stars.