Solar Storm Warning - Coursework Example

What two forces are balanced in gravitational equilibrium? Describe how gravitational equilibrium makes the Sun hot and dense in its core. The two forces that are balanced in gravitational equilibrium are outward pressure and gravity. The outward pressure tries to make an object, like the earth, expand. Gravity tries to make that object contract. Hence gravitational equilibrium is a balance between the force of gravity pulling inward and pressure pushing outward. Gravitational equilibrium makes the Sun hot and dense in its core because as the depth increases the pressure increases which will make the gas to be hot and dense enough to cause nuclear fusion at its core. In the Sun’s core, the weight of the layers above is very large so that the pressure needed to balance it is also large. Pressure is the product of temperature and density, so high pressure means high densities and high temperatures in the core. The energy released by nuclear fusion heats the gas and maintains the pressure that is needed to cause the nuclear fusion. 2. What is the difference between nuclear fission and nuclear fusion? Which one is used in nuclear power plants? Which one is used by the Sun? Nuclear fusion is the combination of two or more nuclei to form a new element with higher atomic number. The amount of energy released in the fusion reaction is equal to E = mc 2. Nuclear fission is splitting of massive nucleus into photos in the form of free neutrons, other subatomic particles, and gamma rays. The main difference between these two processes is that fission is the splitting of an atom into two or more smaller ones while fusion is the fusing of two or more smaller atoms into a larger one. Nuclear fission is the process used in the production of nuclear power. Fission involves splitting the nucleus of a heavy atom, such as uranium. This yields two or more lighter nuclei and a large amount of energy. Fusion, on the other hand, is the combination of two hydrogen nuclei into one helium nucleus, under conditions of extreme heat and pressure. Fusion is the process by which energy is created in the sun. The difference between Nuclear Fission vs Nuclear Fusion: Nuclear Fission Nuclear Fusion Definition Fission is the splitting of a large atom into two or more smaller ones. Fusion is the fusing of two or more lighter atoms into a larger one. Natural occurrence of the process Fission reaction does not normally occur in nature. Fusion occurs in stars, such as the sun. Byproducts of the reaction Fission produces many highly radioactive particles. combination of two hydrogen nuclei into one helium nucleus Energy Ratios: The energy released by fission is a million times greater than that released in chemical reactions; but lower than the energy released by nuclear fusion. The energy released by fusion is three to four times greater than the energy released by fission. Nuclear weapon One class of nuclear weapon is a fission bomb, also known as an atomic bomb or atom bomb. One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction Conditions Critical mass of the substance and high-speed neutrons are required. High density, high temperature environment is required. Energy requirement: Takes little energy to split two atoms in a fission reaction. Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion. 3. Does the Sun’s fusion rate remain steady or vary wildly? Describe the feedback process that regulates the fusion rate. The Sun’s fusion rate is currently in a steady burn. The H -> He (Hydrogen to Helium) fusion rate is not very dependent on temperature/pressure. The primary mechanism of stellar fusion in the Sun is the proton-proton chain. It takes about 1 billion years on average for the sun to crush four H atoms into one He atom. When He -> C starts, then the Sun will become highly unstable. Because the He fusion rate is very much dependent on temperature/pressure. The Sun is in hydrostatic equilibrium between gravity that pulls inwards and increases the temperature and pressure and the radiation pressure that pushes outward. The fusion rate is very sensitive on temperature. An increase of temperature would increase the fusion rate, increase the radiation pressure and expand the core, which then reduces the temperature again. The Sun’s energy output is steady in time. This steadiness results because the rate of fusion is sensitive to temperature. If the Sun’s core were a bit hotter, the fusion rate would increase. This would produce more energy, which would cause the core to expand slightly and cool. The cooling would cause the fusion rate to slow back down until the Sun was back to the original size and temperature and fusion occurred at the same rate. Nuclear fusion requires high temperatures to keep the protons colliding at high enough speeds that they can get close enough to stick together rather than be deflected by the electromagnetic force. The high pressure, generated by the weight of all the Sun’s layers above the core, is required to keep the hot gas in the Sun’s core from exploding into space, shutting off the nuclear reactions. A high particle density is required to sustain a high rate of fusion. 4. Neutrinos probably can’t harm me, but just to be safe I think I’ll wear a lead vest. Neutrinos are subatomic particles produced in nuclear reactions. They move at nearly the Speed of light. Detectors on Earth found only about 1/3rd of the neutrinos. Neutrinos probably can’t harm me, but just to be safe I think I’ll wear a lead vest. This statement is not sensible. Neutrinos pass right through the Earth and would not be diminished at all by a lead vest. 5. In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.” —Galileo Galilei, Italian physicist and astronomer. What does this quote mean? How is it related to astronomy, and what you are learning? In 435 B.C., the Greek philosopher, Anaxagoras, logically deduced that the sun was not just a small glowing circle of light, but a glowing body, a rock that was hundreds of miles in diameter. Because of his outrageous statements, he was exiled from Athens. Now, almost 2500 years later, astronomers have confirmed the current theory that the sun is powered by thermonuclear fusion in its core. Thus, discoveries of the twentieth century conclusively proved Anaxagoras ideas about the sun—it is a glowing ball of plasma. We have also learned much more about the sun, including: It has a solar core with the density 100 times that of water, and a temperature of 15 million degrees Kelvin. The solar surface has 1/20,000,000 the density of water, and a temperature of approximately 6,000 degrees Kelvin. The sun goes through an 11–year cycle of activity. 6. The picture of this week shows the sun during the most active time of its cycle, the solar maximum. What kind of process or formation are you seeing in this picture? How may this affect your life, and life on Earth? Explain Solar maximum is the peak of solar activity. A solar maximum is the period when the sun's magnetic field lines are the most distorted due to the magnetic field on the solar equator rotating at a slightly faster pace than at the solar poles. The solar cycle takes an average of about 12 year cycle to go from one solar maximum to the next with an observed variation in duration of 9 to 14 years for any given solar cycle. Although satellites are on the front line, if there is a powerful surge in energetic particles entering the atmosphere, we may feel the adverse effects down here on Earth too. Due to the X-ray generation of electrons in the ionosphere, some forms of communication may become patchy (or be removed all together), but this isn’t all that can happen. Particularly in high-latitude regions, a vast electric current, known as an “electrojet”, may form through the ionosphere by these incoming particles. With an electric current comes a magnetic field. Depending on the intensity of the solar storm, currents may be induced down here on the ground, possibly overloading national power grids. On March 13th 1989, six million people lost power in the Quebec region of Canada after a huge increase in solar activity caused a surge from ground-induced currents. Quebec was paralyzed for nine hours whilst engineers worked on a solution to the problem. Whilst a solar flare from out Sun, aimed directly at us, could cause secondary problems such as satellite damage and injury to unprotected astronauts and blackouts, the flare itself is not powerful enough to destroy Earth, certainly not in 2012. but in future when the Sun begins to run out of fuel and swell into a red giant, it might be a bad era for life on Earth, but we have a few billion years to wait for that to happen. Quick Quiz Choose the best answer to each of the following. Explain your reasoning with one or more complete sentences. 32. At the center of the Sun, fusion converts hydrogen into (a) plasma. (b) radiation and elements like carbon and nitrogen. (c) helium, energy, and neutrinos. Answer: (c) helium, energy, and neutrinos At the center of the Sun, fusion converts hydrogen into helium, energy, and neutrinos. Fusion is the combination of two hydrogen nuclei into one helium nucleus, under conditions of extreme heat and pressure. Fusion is the process by which energy is created in the sun. Chapter 11, "Surveying the Stars," page 328, review questions 5, 10, 12, 24, and 31 5. What do we mean by a star’s spectral type? How is a star’s spectral type related to its surface temperature and color? Which types of stars are hottest and coolest in the spectral sequence OBAFGKM? In astronomy stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromospheres. The higher the surface temperature, the farther up the ladder the spectral type goes, from type M to type O. Also, the color of the star is directly related to its surface temperature, beginning from red, to orange, to yellow, to yellow-white, to white, to blue-white, and then to blue. The actual mass of a star and its age can play a huge difference in the surface temperature of a star, but the spectral type and color of a star are dependent solely on its surface temperature. Most stars are currently classified using the letters O, B, A, F, G, K, and M where O stars are the hottest and the letter sequence indicates successively cooler stars up to the coolest M class. 10. What do we mean by a star’s luminosity class? What does the luminosity class tell us about the star? Briefly explain how we classify stars by spectral type and luminosity class. A classification of stellar spectra according to luminosity or a given spectral type is called as stars luminosity class. The luminosity class broadly indicates whether a star is a dwarf, a giant, or a super giant since luminosity is directly related to surface area. Luminosity class is expressed as a Roman numeral, from I to V, and appears after the spectral type; The Harvard classification system is a one-dimensional classification scheme. Stars vary in surface temperature from about 2 to 40 kK (2,000 to 40,000 Kelvins). Physically, the classes indicate the temperature of the star's atmosphere and are normally listed from hottest to coldest, as is done in the following table: Class Temperature[8] (kelvins) Conventional color Apparent color[9][10][11] Mass[8] (solar masses) Radius[8] (solar radii) Luminosity[8] (bolometric) Hydrogen lines Fraction of all main sequence stars[12] O ? 33,000 K blue blue ? 16 M? ? 6.6 R? ? 30,000 L? Weak ~0.00003% B 10,000–33,000 K blue to blue white blue white 2.1–16 M? 1.8–6.6 R? 25–30,000 L? Medium 0.13% A 7,500–10,000 K white white to blue white 1.4–2.1 M? 1.4–1.8 R? 5–25 L? Strong 0.6% F 6,000–7,500 K yellowish white white 1.04–1.4 M? 1.15–1.4 R? 1.5–5 L? Medium 3% G 5,200–6,000 K yellow yellowish white 0.8–1.04 M? 0.96–1.15 R? 0.6–1.5 L? Weak 7.6% K 3,700–5,200 K orange yellow orange 0.45–0.8 M? 0.7–0.96 R? 0.08–0.6 L? Very weak 12.1% M ? 3,700 K red orange red ? 0.45 M? ? 0.7 R? ? 0.08 L? Very weak 76.45% According to luminosity the classification is as follows 12. Which stars have longer lifetimes: massive stars or less massive stars? Explain why. The less massive stars have longer lifetimes because larger stars burn up fuel faster to maintain their size. The more massive the star the shorter is its lifespan. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence. More massive stars can explode as a supernova or collapse directly into a black hole. 24. All giants, supergiants, and white dwarfs were once main- sequence stars. True Giants make it to the sequence in 2 million years, the sun like ones in 20 million years. Main sequence is the period of life of star where hydrogen converts to helium. Most stars, including the sun, are main sequence stars, fueled by nuclear fusion. For these stars, the hotter they are, the brighter. These stars are in the most stable part of their existence; this stage generally lasts for about 5 billion years. As stars begin to die, they become giants and super giants. These stars have depleted their hydrogen supply and are very old. The core contracts as the outer layers expand. These stars will eventually explode (becoming a planetary nebula or supernova, depending on their mass) and then become white dwarfs, neutron stars, or black holes Smaller stars (like our Sun) eventually become faint white dwarf, that are below the main sequence. These hot, shrinking stars have depleted their nuclear fuels and will eventually become cold, dark, black dwarfs. 31. Which of these stars has the longest lifetime? (a) a main- sequence A star (b) a main-sequence G star (c) a main- sequence M star The colder the star, the longer is the life. Hottest are O, coldest are M with M being the coldest, so those are the longest living ones. Reference 1. BrainyMedia.com. (2007). BrainyQuote. Retrieved on May 23, 2011, from http://www.brainyquote.com/quotes/authors/g/galileo_galilei.html. 2. Fusion rate, retrieved on May 24, 2011, from http://www.classle.net/bookpage/sun-and-its-solar-system 3. Fusion and fission, retrieved on May 22, 2011, from http://en.wikipedia.org/wiki/Proton-prot… 4. Barnes-Svarney, Patricia. The New York Public Library Science Desk... Retrieved on May 24, 2011, from, http://www.enotes.com/science-fact-finder/energy/what-difference-between-nuclear-fission-nuclear 5. Nuclear Fission vs Nuclear Fusion - Difference and Comparison , retrieved on 24th May from http://www.diffen.com/difference/Nuclear_Fission_vs_Nuclear_Fusion#ixzz1NGCKu0V1 6. Balanced gravitational equilibrium, retrieved on 24th May, 2011, from http://answers.yahoo.com/question/index?qid=2009041819... 7. Solar maximum, retrieved on May 24, 2011 from, http://www.redicecreations.com/article.php?id=718 8. Solar maximum, retrieved on May 24, 2011 from, http://www.2012supplies.com/what_is_2012/solar_maxim.html 9. Solar Storm Warning 2011-2012 , retrieved on May 24, 2011 from http://science.nasa.gov/headlines/y2006/10mar_stormwarning.htm 10. 2012: No Killer Solar Flare, Ian O'Neill(2008), retrieved on 25th May 2011 from http://www.universetoday.com/14645/2012-no-killer-solar-flare/ 11. Colors, Temperatures, and Spectral Types of Stars, retrieved on 25th May 2011 from https://www.e-education.psu.edu/astro801/content/l4_p2.html Read More