What is a nova Ancient observers of the night sky thought it to be an
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What is a nova? Ancient observers of the night sky thought it to be an amazing occurrence in itself. These magically appearing stars were given the name nova, meaning new star, for lack of a scientific explanation. This mysterious oddity has started to unfold as technology has increased.
By definition, a nova is a star that increases its magnitude over a period of hours then goes back to its original state. The magnitude of a star is important because it represents its luminosity. Keeping this in mind, why would a star behave in such a manner? The answer would be in the mechanics of the system occurring.
Through increasing technology, we have been able to get a closer view. Astronomers have discovered that the phenomenon is related to binary star systems.
These systems consist of two or more stars that share a common center of mass which keeps them in constant gravity with each other. It is easier to understand the concept by using the example of how the moon orbits the earth. Although this example shows two solid masses, the same can occur with gaseous masses. At this point we have only scratched the surface. Now we must go inside the system to see what makes it tick.
We know that the stellar system is composed of two stars orbiting each other. In the beginning these stars form out of the same interstellar cloud but evolve at different rates. As the lifecycle of the stars proceed, one of the stars will become a white dwarf while the other is somewhere within the mainstream. This becomes the perfect environment for a nova to happen. The process begins within the Roche lobe (see figure 1), pear shaped regions around the stars in the binary system, the lobes define the space within each starís gravity dominates.
The white dwarf siphons off matter from the companion star creating an accretion disc (see figure 2). The matter accumulates, and a thin layer of hydrogen forms on the surface of the white dwarf. The hydrogen eventually builds in pressure and heat causing a thermonuclear explosion that blows off the outer layers of hydrogen causing a rise in the light output from the system (see figure 3). This explains the increase in magnitude of the white dwarf in the system. The nova can change by ten to twelve magnitudes in a few hours and typically have an absolute (true luminosity) magnitude of a negative seven.
A nova that has been observed to have multiple outbursts is called a recurrent nova.
This discovery changed the original concept of a nova. What was once thought to be the outcome of a single star is now know to occur in a binary star system. Both old and new technology combined has allowed us to redefine the mechanics of novae. What would the ancients think now? I can say for myself that nova means more than the name of a series I watched on KPBS or the name of a one hit wonder band in the eighties (alda nova). It is an amazing phenomenon that occurs in space which seems simple yet complex. Simple because of its mechanics and complex because novae can only occur in special situations. Had this not been the topic that I picked I would not have clue one about them. My search on the internet was difficult as I began with the definition which was all of one sentence. After confirmation on the scope of the paper I was able to see more than the definition. I believe this paper is more than just understanding the concept of a nova. This assignment was specifically bound to the internet which made overall information countless but specific information somewhat more difficult. I had the ability to pick and choose the information but was it all correct?
What bothered me the most was trying to find sites where I could understand what was being said and see the concept through use of visual aid. Search after search I was able to find enough information or what I thought was enough information for my paper.
Even though I was able to gather enough information to explain the concept of a nova it wasnít enough to fill three pages. This upset me the most. Its preciseness leaves little to
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Astronomy, Star types, Stellar evolution, Light sources, Exotic matter, White dwarf, Nova, Binary star, Star, Binary system, Variable star, Supernova
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