The Evolution of Stars Essay

Stars and Interstellar Medium

Stars are heavenly bodies (excluding planets) that are visible at night and resemble fixed light points. The interstellar medium is the matter found between stars. Interstellar gas is composed of helium and hydrogen while the dust is mainly comprised of carbon, ice, silicates, and iron compounds. Stars form when a section of a dust cloud begins to contract under its gravitational force. It becomes hotter during its collapse until nuclear fusion starts to occur in the core. Interstellar clouds are normally stable; therefore, shock might be required to start the collapse. The main sequence stage of a star is defined by its ability to fuse its hydrogen atoms into helium. At this stage, the hydrogen is turned into helium; the star enjoys most of its life at this stage. The stability of the star is achieved because the star's light pressure from its energy balances out its gravitational collapse. Ninety percent of stars are main sequence stars, such as the sun (Redd, 2015).

White Dwarfs

When a low mass star leaves the main sequence, it becomes a white dwarf. The remnants have a high density such that a teaspoon of the matter weighs 5.5 tons. After billions of years, the white dwarf cools and becomes a black dwarf, which is invisible since their emitting temperature matches the microwave background's temperature (Futurism, 2014).

Supernovae and Neutron Stars

After a high mass star leaves the main sequence, it dies more violently. Big stars create supernovae towards their death; supernovae explode while flinging their matter into space at a speed of 9,000-25,000 miles/second. The remnant materials are heavy elements, including iron. The core of the star forms a neutron star or a black hole. Neutron stars are rare, mysterious, and destructive objects with a high density; a cubic meter weighs almost 400 billion tonnes.

References

Futurism. (2014, January 15th). The Life Cycle of a Star. Retrieved from Futurism: https://futurism.com/the-life-cycle-of-a-star/

Redd, N. T. (2015, May 5th). Main Sequence Stars: Definition & Life Cycle. Retrieved from Space.com: https://www.space.com/22437-main-sequence-stars.html