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The Star Cycle. By: J.D. Varnado. The Conception of a Star.
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The Star Cycle By: J.D. Varnado
The Conception of a Star A forming star is known as a protostar. The picture on the left is a picture of a nebula that a star can form from. A gravitational center will form and will pull atoms towards the center. If it becomes dense enough the cloud will collapse on itself.
Equilibrium • The goal of every star is to reach and maintain Equilibrium. Equilibrium is when gas pressure and the force of gravity in a star are equal. The gas pushes light and heat out, and gravity keeps the star together. When these two forces are relatively stable, then a star is content. When a star cannot maintain equilibrium, it dies.
The Birth of a Star • When a forming star gains equilibrium, two things can happen. If the temperature needed to maintain equilibrium is not reached, it becomes a brown dwarf. If the temperature is reached, nuclear fusion begins, and the star is born.
The Main Sequence Stars • Main sequence stars make up about 90% of all stars. Their energy comes from converting Hydrogen to Helium. Yellow Dwarfs (like our sun) and Red Dwarfs are these types of stars.
Giant Stars A Giant Star forms when the core temperature of a star increases, making the star to expand to radiate the energy produced by burning Helium. Red Giants and Blue Giants are types of Giant Stars.
Supergiant Stars • Supergiant stars are among the most massive stars. • Their radii can sometimes reach 1000 solar radii or 50 solar radii. • Red supergiants are usually larger then blue supergiants, according to the Stefan-Boltzmann law
Supernova Explosion • Supernova explosions occur at the end of a star's lifetime, when its nuclear fuel is exhausted and it is no longer supported by the release of nuclear energy. If the star is particularly massive, then its core will collapse and in so doing will release a huge amount of energy. This will cause a blast wave that ejects the star's envelope into interstellar space. The result of the collapse may be, in some cases, a rapidly rotating neutron star that can be observed many years later as a radio pulsar.
Bibliography • http://aspire.cosmic-ray.org/labs/star_life/starlife_proto.html • http://aspire.cosmic-ray.org/labs/star_life/starlife_proto.html • http://aspire.cosmic-ray.org/labs/star_life/starlife_equilibrium.html • http://www.enchantedlearning.com/subjects/astronomy/stars/startypes.shtml • http://www.daviddarling.info/images/red_dwarf_art.jpg • http://starchild.gsfc.nasa.gov/Images/StarChild/solar_system_level1/sun.gif • http://www.universetoday.com/am/uploads/2005-0208dwarf-full.jpg • http://aspire.cosmic-ray.org/labs/star_life/starlife_main.html • http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/971016.html • http://www.lancs.ac.uk/ug/hilditch/pic3.gif • http://astro.uchicago.edu/~grodnick/gallery/iotw/reflect.gif • http://www.sternwarte.uni-erlangen.de/~ai32/HD92207.jpg • http://content.answers.com/main/content/wp/en/6/65/CygnusLoop.jpeg • http://heasarc.gsfc.nasa.gov/docs/snr.html