Zacks Astronomy Presentation Outline

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<ul><li><p>8/13/2019 Zacks Astronomy Presentation Outline</p><p> 1/5</p><p>Hertzsprung-Russell Diagram</p><p>A Scattergraphing of Stars showing their absolute magnitudes, or luminosities</p><p>versus their spectral types, or classifications, and effective temperatures.</p><p>It is a compilation of stars, nota map.</p><p>The X axis would be the Color and Spectral class, and the Y axis would be the</p><p>Luminosity and Absolute Magnitude.</p><p>Each star is represented by a dot, possibly colored depending on the intricacy of the</p><p>diagram</p><p>The diagonal line cutting through the entire graph is known as the main sequence.</p><p>This is where the majority of stars fall under.</p><p>Luminosity is the amount of energy a star radiates in one second, but its commonlyviewed as how bright or dim the star appears to be, which is also correct.</p><p>The X Axis (Color and Spectral class), represents the stars surface temperature, not</p><p>the core temperature. The Temperature is measured using the Kelvin scale. Its</p><p>worth pointing out that the reference point 0 does not start in the left and increase</p><p>as it goes right. The higher/hotter temperatures are on the left and it cools as it goes</p><p>right.</p><p>The Diagram was created around 1910 by Ejnar Hertzsprung and Henry Norris</p><p>Russell. It was an important development toward the understanding of Stellar</p><p>Evolution.</p><p>The Hertzsprung-Russell Diagram is an way of categorizing Stars by</p><p>comparing their Color and Spectral Class (which is given by the surface</p><p>temperature) by their Luminosity and Absolute Magnitude (the brightness). It was</p><p>important because it highlights a relationship between the two, which is the hotter a</p><p>star is, the higher the luminosity will be, and vice versa. The way it is ordered is by</p><p>having the Color and Spectral class as the X-axis, and the Luminosity and Absolute</p><p>Magnitude as the Y-axis. Its important to know that we assign luminosity based</p><p>around the reference point, which is our sun. So anything hotter than our sun will</p><p>increase with positive numbers, while anything cooler will be assigned a negative</p><p>number. Also, The temperature for the X-axis is measured using the Kelvin scale,and the X-axis does not begin from left to right. 0 Kelvin would actually begin on the</p><p>right, with temperatures increasing as it goes left. It also only represents the stars</p><p>surface temperature, not the core temperature. The color, as given by the surface</p><p>temperature, will change as we look right to left. The coolest stars will be red, and</p><p>itll go through orange, yellow, green, white, blue, then violet as its temperature</p><p>increases. The human eye cant actually see stars as green or violet so theyll appear</p><p>white or blue respectively. Most of the stars plotted on the H-R Diagram fall under</p></li><li><p>8/13/2019 Zacks Astronomy Presentation Outline</p><p> 2/5</p><p>the Main Sequence. The main sequence is the line of best fit, drawn within the</p><p>average of all stars that highlight the relationship between Surface temperature and</p><p>Spectral class, and Luminosity. The hot bright stars will be on the top left, while the</p><p>cool dim stars will be on the bottom right. Scientists Ejnar Hertzsprung and Henry</p><p>Norris Russell created the diagram in 1910 and it was an important step in the right</p><p>direction to fully understanding stellar evolution.</p><p>source: http://aspire.cosmic-ray.org/labs/star_life/hr_diagram.html</p><p>NEUTRON STAR</p><p>Neutron star is actually a stellar remnant of a star gone supernova</p><p>As the Name might suggest, its composed almost entirely of neutrons, which are</p><p>subatomic particles with no electric charge and a higher mass than protons.</p><p>They are very hot. Newly formed ones start around 10^11 Kelvin to 10^12 kelvin.But within a few years it drops to around 10^6 Kelvin.</p><p>Most of the light emitted is in X-rays. They appear white in visible light because it</p><p>emits the same amount of energy in all parts of the visible spectrum.</p><p>Neutron stars are impervious to further collapse by quantum degeneracy pressure</p><p>due to the Pauli Exclusion Principle, which in very simple terms states that no two</p><p>neutrons can occupy the same place and quantum state at the same time.</p><p>1 Solar mass is equal to 10^30 kg. Which is about two nonillion kg</p><p>Your average neutron star has the mass of about 1.4-3.2 solar masses</p><p>The density of a neutron star is comparable to a Boeing 747 condensed to the size of</p><p>1 grain of sand, or the entire human population to the size of a sugar cube.</p><p>Surface gravity is so high on a neutron star, that any object that is falling on the</p><p>surface of the star, is pulled with tremendous force into the star by its gravity, and</p><p>the force of impact would be so great, that it would destroy the atoms of whatever</p><p>the object is, rendering all of its matter, in most respects, identical to the rest of the</p><p>star.</p><p>The structure of a neutron star is currently defined by mathematical models. Theatmosphere is hypothesized to be a few, micrometers thick. The crust would be</p><p>extremely hard and smooth due to the high surface gravity. The outer part of it</p><p>would be composed of ions and electrons, while the inner crust would be of</p><p>electrons, neutrons and nuclei. Next would be the outer core which is called the</p><p>Neutron Dip, and its full of nuclei, electrons, and neutrons that become smaller and</p><p>smaller until the core is reached. There is acutally quite a bit of speculation on what</p></li><li><p>8/13/2019 Zacks Astronomy Presentation Outline</p><p> 3/5</p><p>exactly the core would be since it would theoretically be full of things so dense and</p><p>so small. They range from strange matter, to ultra dense, quark degenerate matter.</p><p>A Neutron Star is actually a stellar remnant of a star gone supernova. As the</p><p>name might suggest, its composed almost entirely of neutrons, which are subatomicparticles with no electric charge and a higher mass than protons. These stars are</p><p>very hot. Newly formed ones start around 10^11 Kelvin to 10^12 kelvin. But within</p><p>a few years it drops to around 10^6 Kelvin. Most of the light emitted is in X-rays.</p><p>They appear white in visible light because it emits the same amount of energy in all</p><p>parts of the visible spectrum. Neutron stars are impervious to further collapse by</p><p>quantum degeneracy pressure due to the Pauli Exclusion Principle, which in very</p><p>simple terms states that no two neutrons can occupy the same place and quantum</p><p>state at the same time. 1 Solar mass is equal to 10^30 kg. Which is about two</p><p>nonillion kg. Your average neutron star has the mass of about 1.4-3.2 solar masses.</p><p>The density of a neutron star is comparable to a Boeing 747 condensed to the size of</p><p>1 grain of sand, or the entire human population to the size of a sugar cube. Surfacegravity is so high on a neutron star, that any object that is falling on the surface of</p><p>the star, is pulled with tremendous force into the star by its gravity, and the force of</p><p>impact would be so great, that it would destroy the atoms of whatever the object is,</p><p>rendering all of its matter, in most respects, identical to the rest of the star. The</p><p>rotation of newly formed neutron stars can be as fast as several times per second.</p><p>The structure of a neutron star is currently defined by mathematical models. The</p><p>atmosphere is hypothesized to be a few, micrometers thick. The crust would be</p><p>extremely hard and smooth due to the high surface gravity. The outer part of it</p><p>would be composed of ions and electrons, while the inner crust would be of</p><p>electrons, neutrons and nuclei. Next would be the outer core which is called the</p><p>Neutron Dip, and its full of nuclei, electrons, and neutrons that become smaller andsmaller until the core is reached. There is acutally quite a bit of speculation on what</p><p>exactly the core would be since it would theoretically be full of things so dense and</p><p>so small. They range from strange matter, to ultra dense, quark degenerate matter.</p><p>There are 19 known sub-types of Neutron Stars. And we know of 2000 within the</p><p>Milky Way and the two Magellanic Clouds.</p><p>Source: http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html</p><p>MAIN SEQUENCE STAR</p><p>A star that falls within the main band of stars as seen on the Hertzsprung-Russell</p><p>diagram.</p><p>All main sequence stars are in hydrostatic equilibrium, which is where outward</p><p>thermal pressure is balanced by inward gravitational pressure.</p></li><li><p>8/13/2019 Zacks Astronomy Presentation Outline</p><p> 4/5</p><p>The main sequence is sometimes divded into upper and lower parts, based on the</p><p>more dominant processes that stars use to generate energy.</p><p>Stars that are below around 1.5 solar masses tend to fuse hydrogen atoms together</p><p>to form helium, which is called the Proton-Proton chain.</p><p>Stars that are above that mass use a fusion, that uses Carbon, nitrogen, and oxygen,</p><p>as a way to fuse helium from hydrogen atoms, called the CNO Cycle.</p><p>Stars in the Main Sequence with more than 2 solar masses undergo convection in</p><p>their core, which stirs up the newly created helium and maintain the right</p><p>conditions for fusion to occur.</p><p>Main Sequence stars below 2 solar masses have cores that are entirely radiative</p><p>with convection zones near the surface</p><p>Usually, the more massive a star is, the shorter the lifespan will be on the mainsequence.</p><p>Once the hydrogen fuel at the core as been depleted, the star will evolve away from</p><p>the main sequence</p><p>After that it can become either a white dwarf, or a red giant, depending on its mass.</p><p>The very massive stars can go supernova or collapse in on itself in a black hole.</p><p>A Main Sequence Star is a star that falls within the main band of stars as seenon the Hertzsprung-Russell diagram. All main sequence stars are in hydrostatic</p><p>equilibrium, which is where outward thermal pressure is balanced by inward</p><p>gravitational pressure. The main sequence itself can be divided into upper and</p><p>lower parts, based on the more dominant processes that stars use to generate</p><p>energy. Stars that are below around 1.5 solar masses tend to fuse hydrogen atoms</p><p>together to form helium, which is called the Proton-Proton chain. Stars that are</p><p>above that mass use a fusion, that uses Carbon, nitrogen, and oxygen, as a way to</p><p>fuse helium from hydrogen atoms, called the CNO Cycle. Stars in the Main Sequence</p><p>with more than 2 solar masses undergo convection in their core, which stirs up the</p><p>newly created helium and maintain the right conditions for fusion to occur. Main</p><p>Sequence stars below 2 solar masses have cores that are entirely radiative withconvection zones near the surface. Usually, the more massive a star is, the shorter</p><p>the lifespan will be on the main sequence. Once the hydrogen fuel at the core as</p><p>been depleted, the star will evolve away from the main sequence. After that it can</p><p>become either a white dwarf, or a red giant, depending on its mass. The very</p><p>massive stars can go supernova or collapse in on itself in a black hole.</p><p>Source: http://spiff.rit.edu/classes/phys230/lectures/star_age/star_age.html</p></li><li><p>8/13/2019 Zacks Astronomy Presentation Outline</p><p> 5/5</p></li></ul>