Discussion Questions on Astronomy - Paper Example

1. Post a diagram of the three interior layers of the Sun. Describe the role of the proton-proton chain in the generation of energy in the Sun's core. Detail the different conditions present in, and energy transport through each of the remaining layers.

The diagram below shows the three interior layers of the sun which are the core, convection zone, and radioactive zone.

Role of the proton chain in the generation of energy in the Sun's core. Detail the different conditions present in, and energy transport through each of the remaining layers.

The proton chain reaction involves a nuclear fusion reaction by which hydrogen is converted to helium by the stars. This then results in the generation of energy in the suns core because the sun will be able to fuse with 620 million metric tons of hydrogen per second. The fusion occurs if the condition of the kinetic energy of the-the protons is so high such that it overcomes the Coulomb repulsion. Therefore, the proton-proton reactions create Diprotons in the sun and are subsequently decayed back into two protons. During transportation of energy, the sun uses radiation to transmit power from inner core to the convectional zone. This involves energy being carried out by photons that are emitted at one point and absorbed by another point. Furthermore, the energy is carried as electromagnetic radiation from the core through radioactive diffusion method. On reaching convection zone, the energy is transported by convection to the photosphere.

Describe the role of neutrino studies and helio-seismology in assisting astrophysics in understanding the interior of the Sun.

Neutrino is a tiny and massless particle that travels at light speeds. Since it the interior part of the sun is intensively bright and hard to look, the neutrino particles will be used because it diminishes the light. The neutrinos located at the surface of the sun enables the astrophysics to study the fusion of the sun, central pressure, density, and temperature. On the other hand, helio-seismology helps in analyzing solar interior through observations of wavers around the surface of the sun. It is useful to astrophysics because it improves the understanding of suns inner surface and provides a detailed map of suns internal rotation and structure.

2. List the four terrestrial planets and a unique characteristic about each. List the four Jovian planets and a unique characteristic about each. What three conditions must an object meet to be considered a planet? Which of these conditions do Pluto and Ceres fail?

The first four terrestrial planets are Mercury, Venus, Earth, and Mars. Mercury is the smallest terrestrial planet in the solar system and is dense. Venus is the hottest planet because of a large amount of thick carbon monoxide that traps heat. Earth is unique because it is the largest among the four planets and only one with large regions with liquid water. Moreover, Mars is unique because it has a giant mountain in the entire solar system.

Jovian planets include Jupiter, Saturn, Uranus, and Neptune. Jupiter is two and a half times more massive than all other planets combined. Saturn is unique because it is the least dense planet in the solar system. Uranus is the only planet that orbits the sun on its side while Neptune is unique because it has a higher mass. To be considered a planet, an object must be in orbit around the sun, should have sufficient mass to assume hydrostatic equilibrium and should have cleared the neighborhood around its orbit. Pluto fails to fit in third criteria because it has no gravitational attraction to clear out debris in its orbit around the sun. Ceres also is not a planet because it does not dominate its orbit.

Unit 4

3. Describe in detail the Hertzsprung Russell (HR) diagram. Include the information contained on the vertical and horizontal axes, as well as the location of a Red Super Giant, a high mass central sequence star, a Sun-like star, and low mass main sequence star, and a white dwarf star.

The HR diagram is fundamental in studying stellar evolution. The diagram plots the temperature of the stars against their luminosity and absolute magnitude. The diagram has three main parts; the main sequence, the giant branch and white dwarfs. The main sequence starts from upper left to bottom right and is where the stars spend over 90% of their time burning helium and hydrogen in their cores. The stars in this region have Morgan-Keenan luminosity class. The second area contains supergiant and red giant stars that have low temperatures and high luminosities that is associated with large radii. The Stars enter this stage after exhausting their hydrogen fuel in its cores and have started using helium. Lastly, the stars enter the final evolutionary stage of low mass stars. This stage is mainly occupied by white dwarf stars which are located at the bottom left of the diagram. White dwarf stars are very hot but have low luminosities due to its small size. The vertical axis shows luminosity of the stars while the horizontal axis indicates the temperature changes.

The stars evolve by going through evolutionary stages where it corresponds to changes in its temperature and luminosity. The stars burn hydrogen and helium at the main sequence before it becomes giant at class I to III. The stars evolution is dictated by their internal structure and the way they produce energy. In the Asymptotic Giant Branch, the star cools, expands and starts to be brighter. Additionally, it starts to burn its nuclear fuel faster and cools to the extent that it dusts begins to condense. It starts to pulsate heavily until it consumes the hydrogen in its outer shell.

4. Compare the life cycles of heavier stars versus lighter stars. Include the role of mass in determining the temperature, color, lifespan, and ultimate fate of the star

Low mass and high mass stars have several similarities and differences regarding their life cycles. Both are similar regarding starting the process as they begin with a huge collection of helium and hydrogen gases. They also release energy through nuclear fusion between two hydrogen nuclei fusion to produce helium nucleus. However, the two stars can have different stages in their life cycle. Lighter stars rotate more quickly than more massive stars thus producing more solar eruptions of x-rays. Furthermore, the time taken by lighter and heavier stars for the nuclear fusion to occur are different. Nuclear fusion for lighter stars happens much faster leading to high pressure, temperatures, and conversion of other elements.

The heavier stars have shorter lives than lighter stars, and they burn out faster. Heavier stars also are mostly violent and explosive when developing into a neutron star at the end of the lifecycle. Lighter stars, on the other hand, have longer lives and never get so hot than heavier stars. The lower mass star ultimately becomes white dwarf stars at the end of life cycle.

Unit 5

5. Provide a description of our home galaxy, the Milky Way. Include in your description the location and stellar populations (new stars/ old stars) of the central bulge, disk, and halo. Also provide details such as the Hubble classification, disk structure, location of star-forming regions, and the best estimate of the number of spiral arms.

Milky way galaxy involves a spiral galaxy that is mainly our home. It contains the sun at the center and is seen as a swath of light at the night sky. Milky Way galaxy contains a bar across its middle, two major arms, and two minor arms. In addition to that, it contains two smaller spurs that hold the sun and the solar system. Moreover, the milky way is always rotating and moving the arms through space. The galaxy is surrounded with by a massive halo of hot gas that lights for hundreds of thousands of years. Halo gas is estimated to be equal to all stars in the galaxy, and it is spinning quickly.

At its center, there is the galactic bulge which is collection of many stars, gas, and dust. This makes an individual to see only a few stars in the galaxy. Inside the galaxy center, there is a black hole that supplies dust and gas into the galaxy. The disc extends from the nucleus out to about 75,000 light years and has a thickness of about one-fifth diameter and small areas with dust, gas and small stars. The estimated number of spiral arms is about 100 to 400 billion stars and 100 billion planets.

Unit 6

6. Write a post detailing the best scientific model we have for galaxy formation.

Please include a description of the three main galaxy types, their Hubble classifications, and likely stellar populations (old stars/ new stars).

The hybrid hierarchical model is the best scientific model for galaxy formation and evolution. This model provides a good description of observed galaxies and is a combination of monolithic model and hierarchical model. This model believes that galaxy formation was from the early times of the universe. Additionally, the CMB radiation that is seen today was emitted thousands of years ago after the world was born. The remaining small variations in radiations in the sky showed that the distribution of matter was clumped. Consequently, the clumps of matter formed the inner parts of the first protogalaxies that ultimately matured into galaxies available today.

Nevertheless, the hybrid hierarchical model shows how the three main galaxy types evolved. The initial protogalaxies merged to form large structures that finally created the galaxies. The galaxies merged while condensing until it produced spheroidal shaped galaxies. This is believed to have developed the spirals that are characterized by spheroidal bulges in today galaxy. In addition to that, if additional merges would have occurred, the elliptical galaxies would be formed. The more considerable condensation of the regular galaxies results to multiple collisions that give rise to irregular galaxies.

The Hubble classified the elliptical galaxies according to the ellipticity of the galaxy and given a Hubble type of E = 10 * (1-b/a) where a is semi-major axis, and b is the semi-minor axis of the eclipse. Moreover, Hubble classified spiral galaxies from early type to late-type using the amount of winding of the spiral arms and luminous ratio of the bulge when likened to the disk. Lastly, the irregular galaxies are classified into Irr I that showed small clue of organized structure and Irr II who are irregular. Besides, the model analyzed the stellar populations that involved a collection of stars that resemble each by chemical composition and spatial distribution.

7. Summarize the modern scientific model of cosmology and the age of the universe. Provide at least three different pieces of observational evidence to support the details in your description.

Bing Bang theory has successfully explained the critical cosmological observations and the age of the universe. Bing Bang theory states that the universe expansion began way back in the past when it was having massive pressure and density. It cooled as it grew older and there started the formation of stars and galaxies currently available. Moreover, the theory is based on three pillars which are Hubbles law, the cosmic background radiation and the abundance of deuterium and helium in the atmosphere.

The Hubbles law observed the distances and velocity of galaxies and concluded that the universe is expanding. Hubble further explained that expansion is seen by the ever decreasing density of low density and cold world. The universe tends to be hotter and of higher densities according to the theory. The second pillar is the Helium abundance. Observation of Helium is one of the predictive observation, and it states that universe starts by being hot and then cools faster while expanding. This shows helium was formed at some point but the cold...