Astronomy Explain How the Hertzsprung-Russell Diagram Is Essay

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Astronomy

Explain how the Hertzsprung-Russell diagram is constructed of the four main groupings of stars. Identify characteristics of the four main groupings of stars on the diagram. How are the axes of graph labeled?

The Hertzsprung-Russell diagram is much like a common graph used in mathematical subjects like algebra and other mathematical domains. Like any graph, there is an X axis and a Y axis with each axis representing different majors traits of stars. The axes of the graph are temperature/spectral type (the x-axis) and luminosity/absolute magnitude. The main sequence of stars is a range of starts that are high luminosity and hot down to stars that are low luminosity and cool. The stars on the lower left end of the diagram (near the X/Y intercept) are the white dwarfs. As one moves from left to right on the Hertzstrung-Russell graph, the effective temperature in question gets lower Just as one example, the temperature in Kelvin at the X/Y intercept could be graphed as 30,000 degrees Kelvin while the right side of the graph would be much lower, let's say at something like 2,000 or 3,000 Kelvin. As the effective temperature gets smaller, the increasing color index would increase.. The color index ranges both just above and just below zero. The spectral class, from left to right, would be O, B, A, F, G, K and M (NASA, 2013).

The other primary groups on the Hertzstrung-Russell diagram are the giants (otherwise known as red giants) and super giants. The latter ranges across the entire top end of the Hertzstrung-Russell diagram. Giants and super giants are both high on the luminosity index. The giants/red giants group has a moderately high amount of luminosity. However, super giants are even higher and this is the reason why they are not grouped together because there is a noticeable difference in the luminosity traits of the two groupings. (NASA, 2013).

Examples of super giants would include stars like Rigel, Deneb, Canopus, Betelguese, and RW Cephei. Giants would include RR Lyrae, Aldebaran and Mira. White dwarfs would include Sirius B. And Procyon B. Main sequence stars would include Barnard's Star, Proxima Cen, Achenar, Regulus, Altair, Sirius and the Sun in the Earth's solar system. Stars that are not in the same class generally share one of the two main dimensions but not the other. For example, Barnard's Star and Mira are the same in terms of spectral class and effective temperature but they are far apart in terms of absolute magnitude and luminosity (NASA, 2013).

2."A Star is Born!" In a step-by-step fashion, reconstruct the birth of a star. In your answer, include interstellar medium, proto-star, and how stellar equilibrium is finally reached.

The interstellar medium includes all of the matter that exists in space such as cosmic rays, gas (in its many forms), radiation and so forth between the different star systems within a given galaxy or between galaxies. There are also multiple phases of the interstellar medium. The phases and their arc depend on the composition of the matter in question, but there is always a high amount of hydrogen (nearly 90% of the gas present) with the remaining gas being mostly helium and metals (NASA, 2013).

The interstellar medium is relevant to star formation because the gasses and matter present in the interstellar medium are the birthplace of stars. The interstellar medium is involved both in the birth and death of stars and the physical integration is high and ongoing. There is formation, then ongoing interaction and then interstellar extinction, in that order (NASA, 2013).

The starting point of a star is when it forms into a proto-star. This is an object or mass that forms from a giant molecular cloud in space. At a minimum, this process will often take 100,000 years to take place. The typical result of this overall process is the formation of a main sequence star, as mentioned and defined earlier in the definition and discussion of the Hertzstrung-Russell diagram. Proto-stars fall into four major classes, those being 0, I, II and III. 0 is sub-millimeter, I is far-infrared, II is near-infrared and III is visible. The higher the class, the longer it takes for the star to form. Class II is a typical T-Tauri star. Stellar equilibrium is when there is a balance in the forces that would make the star bigger or smaller are in balance. Gravity would make the forces smaller while gas pressure would make it bigger.

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If stellar equilibrium is present, these two items are in balance. As such, the star would not get bigger or smaller if this were the case (NASA, 2013).

3."A Star Dies!" Using the same technique you applied in question 2 above, trace the elements in the demise of stars of low stellar mass, those of medium stellar mass, and those that are very massive. Be sure to describe how each star dies. What determines how long a star lives?

The end state of a star, as intimated by the question, depends on its relative size. A low stellar mass star will become a white dwarf after it dies. A medium mass star will become a neutron star. The very large mass stars will probably become a black hole but that is not known for sure. Put another way, sun-like stars will shift to red giants to planetary nebulas to white dwarfs to black dwarfs. These are stars with under 1.5 times the mass of the sun. Huge stars, which would be stars 1.5 to 3 times that of the sun, would become red super giants, then supernovas and then neutron stars. Stars that are more than three times the size of the sun would shift from red super giants, would go through a supernova and then would become a black hole. What determines when a star goes into its death cycle depends on when it expends its nuclear fuel. The larger the star, the more quickly the fuel is burned and the more violent the reaction when the star dies. For a smaller star like our Sun, the overall life cycle will be 10 billion years. However, stars much larger than the sun will come and go in a just a few million years (NASA, 2013).

4. Explain how Type I and Type II supernovae occur. How can astronomers tell the difference between each type?

To answer the last question first, the major difference between the two types of supernova is the present of hydrogen. There is little to no hydrogen in a type II supernova while it is always present in a type I supernova. However, it should be noted that some supernova are not clearly able to be labeled and thus are called "peculiar" supernova. However, there is another major difference between the two. With a type I supernova, a star is accumulating matter from neighboring planetary bodies and gasses and the accumulation leads to a nuclear reaction igniting and thus destroying the current state of the star. Again, there is no hydrogen in this explosion and this is apparent through the light spectra that they exhibit, which is the main way astronomers are able to tell the difference. Type I -- A supernovas are generally considered to be derived from white dwarf stars. As gas enters the white dwarf, it is compressed and a nuclear reaction ends up happening. Type I-B and I-C supernovas are much like type II but without the hydrogen envelopes, thus why they are not type II supernova (NASA, 2013).

By contrast, the type II supernova is when a star runs out of nuclear fuel and thus collapses under its own weight. There are several traits and events that speak to a type II supernova being present. The heavier elements build up in the center of the star in question making the star exhibit layers in much the same manner as a common onion. The star's core eventually becomes so heavy and massive that it passes a threshold called the Chandrasekhar limit. At this point, the star begins to implode via a process called a core-collapse supernova. The core heats up and becomes more and more dense. The implosion eventually switches back out and away from the star once the implosion bounces off the core and the matter is expelled into space. The typical result of a type II supernova is a neutron star. However, if the star is massive enough things can be different. Type II-L supernovas come from stars that show a steady decline just after the explosion and II-P's stay steady in terms of output before starting to diminish, even after the explosion. However, if the star is massive enough (20 to 30 solar masses), the star will collapse into black holes instead of exploding, at least that is the common and current theory at this time (NASA, 2013).

It has been established that supernovas actually do exhibit an audible sound.....

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