Question 1
The solar system is located in a spiral arm: Orion-cygnus arm. According to (Leong 5), it is a minor spiral arms of the Milky Way galaxy some three thousand five hundred light-years (1100 parsecs) across and approximately ten thousand light years (3100 parsecs) in length. It is also known as local arm, Orion Bridge, local spur and Orion spur.
It is named for the Orion constellation, one of the prominent constellations of the northern hemisphere winter (southern hemisphere) (Leong 26).the brightest stars and numerous famous celestial objects of this constellation- Betelgeuse, Rigel, the stars of the Orion belt, the Orion nebula- are located within the local arm.
The Orion arm is located between the Carina-Sagittarius arms, towards the galactic centre, and peruses arm, towards the outside universe (Leong 32). Within the local spur, the solar system and earth located towards the inner rim in the local bubble, about half the Orion arm’s length, approximately eight thousand parsecs from the Galactic center.
Question 2
Schneider (53) argues that stars are seen orbiting closely at the centre of the galaxy showing its mass as too high to be a super massive black hole. Moreover, according to Schneider (53), some astronauts, during research using telescopes and infrared cameras observed an orbit that moved under the influence of enormous gravity of an unseen object that was orbit’s compact – super massive black hole. Schneider (53) also adds that the movement of the stars to the galactic centre measure the black hole’s mass that goes further to show how gravity affect the movement and lead to the observation of a super massive black hole.
Question 3
Spiral density wave are responsible for grand design spirals. A grand design spiral galaxy is a type of spiral galaxy with standing out and well-defined spiral arms, contrary to multi-arm and flocculent spirals with subtler structural features (Garlick 15). The spiral arms of a grand design galaxy extend conspicuously around the galaxy through many radians and can be seen over a large fraction of the galaxy’s radius. Ten percent of spiral galaxies are categorized as grand design type spirals including M81, M51and M74.
According to Garlick (17), density wave theory is tells more, on the well defined outlook of grand design spirals. The theory argues that the spiral arms are formed inside destiny waves that run around the galaxy at different velocities from the star in the disk. Stars are clumped in dense regions due to gravitational attraction towards the dense materials; their location in the spiral arm may be temporary. When they approach the spiral arm, the force of gravity pulls them towards dense materials; and as they travel along the spiral arm, they are slowed from leaving by the same gravitational pull. This results to material clumping up in dense regions. In the middle of these galaxies are supper massive black holes.
Question 4
The blue shift are not a violation of the Hubble law because, gravity in a cluster within a super cluster of galaxies predominates within that cluster or super-cluster over Hubble expansion (Jones 12). The Andromeda and milky way galaxies are members of the local group of galaxies, so their gravitational interaction and end collision in 2.5 million years is not a violation of the Hubble’s laws and physics.
Hubble’s law is the theory name of physical cosmology that: (1) all objects observed in the deep space are found to contain in the Doppler shift observable relative speed to earth, and to each other. Secondly, the Doppler shift observable relative speed, of various galaxies receding from the earth, is proportional to the distance from the earth and all other interstellar bodies (Jones 26). As a result, the space time volume of observable universe is expanding and Hubble’s law is the observation of this process. The locomotion of astronomical objects due to this expansion is known as Hubble flow. Hubble’s law is considered the first observational basis for expanding space pattern.
Blueshift on the other hand, is any decrease in wavelength (appreciation in frequency); the contrary effect is referred to as redshift. In visible light, this changes the color from end of the spectrum to the blue end (Jones 38). The term also applies in photons outside the visible spectrum (for example x-rays and radio waves) are shifted towards shorter wavelength as well as to shift in the de Broglie wave length of particles. An observer in a gravity well will also see infalling gravitationally blueshifted, explained by general relativity in the same way as gravitational redshift. In a contracting universe, cosmological blueshift would be seen, the expanding universe gives a cosmological redshift, and increase in size is observed to be accelerating. Doppler and gravitational blueshifts are the two types of the blueshift. Doppler blueshift is caused by movement of a source towards an observer while gravitational is where an observer is at a lower gravitational than the source will observe radiation blueshifted to shorter wavelengths.
Question 5
I carried out a Sloan digital sky survey. Quasar’s spectra have redshift between 0.056 and 7.085. Moreover, when I applied Hubble’s law to these red shifts, it showed that there are between 600million and 28.85 billion light-years away (proper distance)(Jones 38). It looked faint when I viewed it from the earth: which is quasar’s property. They are also visible from far due to their luminous nature. The quasar that appears brightest in the sky is 3C 273 in the constellation of Virgo.
Quasars have an average apparent magnitude of 12.8(bright enough to see through a medium size amateur telescope), and has an absolute magnituide4 of-26.7(Jones 39). When it is viewed from a distance of 33 light years, the object would shine as bright as the sun. Quasars luminosity is about 2 trillion times that of the sun ,or 100 times that of the total light of giant galaxies like the milky way. Nevertheless, this assumes that the quasar radiates energy from all directions.
They have all the properties as active galaxies, but they are more powerful: their radiation is ‘nonthermal’. They are brightest in their rest-frame near- ultraviolet wavelength of 121.6 nm Lyman-alpha emission line of hydrogen, but due to the tremendous redshifts of these sources, that peak luminosity has been observed as far to 900.0nm in the nigh infrared. A few quasars show strong radio emission, which originates from jets of matter moving close to speed of light. When viewed down jet, often have regions that appear to move away from the center faster than the speed of light (Jones 40). This is an optical illusion due to the properties of special relativity.
Question 6
It is subtle. A Doppler shift stretches the frequency of light, reason; the object emitting it is receding. A cosmological shift occurrence is due to the frequency stretch expansion of space. In a Doppler redshift, two objects are receding through space (Burser 5). If you pictured the two objects in a coordinate grid, one or both will be changing its coordinates as the two separates. The depreciation in frequency is caused by the fact that it takes an increasingly long time for each crest of wave to reach the receding observer.
In cosmological red shift, the objects might or might not recede through space; even though the space between them is actually expanding. If you imagine them in a coordinate grid-grid itself grows. In this case, the drop min frequency is resulted by the fact that the light waves are literally stretched out, getting longer and longer wavelengths annually, as the space in which they reside stretches around them (Burser 12).
The receding objects can’t recede faster than light speed in Doppler red shift while in cosmological the receding objects can recede faster than the light speed (Burser 24). There is a small discrepancy in the equation for Doppler versus cosmological redshift, so it is feasible to determine which kind you are looking at by measuring their attributes.
Question 7
If the universe expands, the micro waves will cool to near absolute zero and they will be unnoticed. Due to its nigh perfect uniformity, scientists deduce that this radiation’s origin was at a time when the universe was much smaller, hotter, and denser (Burser 25). Universe expansion, result to the stretching out to longer wave length of the light waves.
Astronomers and physicists feel that the Cosmic Microwave Background might display very little fluctuations in temperature, but this data could not be accurately recorded until the flight of COBE because it was the first satellite experiment to gather information from outer space, where all of the background noise from water vapor could be getting rid of (Burser 40). Water vapor causes problems for detecting microwaves because it absorbs microwaves. That makes the microwaves very hard to observe, especially when scientists are observing temperature variations that are the order of micro Kelvin.
Question 8
Strong force is believed to have been formed the second force formed after electroweak force. The universe was so hot or energetic and the forces around us today used to be a unified force. The space expanded during inflationary epoch due to the immensity of the energies initiated (Jones 67). Gradually, the intense energies cooled- still to a temperature that is intensively hot to any that we see around us today, but efficiently to allow forces to gradually undergo symmetry breaking, a kind of repeated condensation from one state to another, leading to the separation of the strong force from the electroweak force and the first particles.
The strong force and the weak force have a short range on which the effect is felt. They are less directly related to the intermediate and large scale structure of the universe than electromagnetism and gravity (Jones 70). Nevertheless, they are vital to the stability and nuclear structure of matter, therefore; changing them would result in a markedly different universe.
This explains why atomic nuclei stick together even though protons have a positive charge (Jones 82). The weak nuclear force is made of W and Z bosons, and is responsible for certain types of radioactive decay. Furthermore, iirc, neutron decay involves interconversion of a neutron into proton, electron neutrino via a W boson.
Question 9
The stellar spectral type that is most likely to have a planet on which advance life exists is G. The G types stars, our sun is G2 (Leong 45). They are long lived 10 billion years and are luminous to have a hospitable zone for life. The M class stars are longer lived but have a smaller hospitable zone for life. Rotation period of a planet would get tidally locked being so nigh to the M star which could make it uninhabitable.
Most notable are the H and K lines of Ca II, which are most eminent at G2. They have even less strong hydrogen lines than F, but along with the ionized metals, they have neutral metals. There is an eminent spike in the G band of CH molecules. G is host to the "Yellow Evolutionary Void"(Leong 50). Supergiant stars seldom swish between O or B (blue) and K or M (red). While they do this, they do not stay for long in the yellow supergiant G classification as this is a tremendously unstable place for a supergiant to be.
Work cited
Leong, Stacy. "Period of the Sun's Orbit around the Galaxy (Cosmic Year)". The Physics Factbook, 2002.
Garlick, Mark Antony. The Story of the Solar System. Cambridge University, 2002.
Schneider, Peter. Extragalactic Astronomy and Cosmology. Springer, (2006). p. 4,
Jones, Mark H, Lambourne, Robert J, and Adams, David J. An Introduction to Galaxies and Cosmology. Cambridge University Press, 2004.
Imamura, Jim. "Mass of the Milky Way Galaxy". University of Oregon. Archived from the original, (August 10, 2006).
Peter Schneider. Extragalactic Astronomy and Cosmology. Springer, 2006.
Wethington, Nicholas. "Formation of the Milky Way". Universe Today, (May 27, 2009).
Buser, R. "The Formation and Early Evolution of the Milky Way Galaxy". Science, 2000.
Wakker, B. P., Van Woerden, H. "High-Velocity Clouds". Annual Review of Astronomy and Astrophysics, 2000.
