Harlow Shapley Views on Galaxy

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Harlow Shapley is renowned for his great work in identifying that the sun was not at the center of our galaxy. Shapley studies spherical groups, galactic structure, Milky Way and shape of the disks with clusters. He made the major discovery in the year 1916. In the year 1912, Harlow Shapley realized the brightness of the clusters and the structure of the galactic structure (Ideas of Cosmology 2).

Later, Shapley realized the widely distributed clusters beneath the Milky Way and seemed to be compact in one smallish region in the direction of the arrangement Sagittarius. As such, the distribution revealed that the galaxy shape took the form of a flat disk having the cluster surrounding the galactic center.

The revelation called for a relook in the solar system focusing on its centrality (Sparke 13). As such, it is worth noting that Harlow Shapley realized the overview orientation of the galaxy size and structure. The distance from the center was determined by the by the calibration of the galactic structure, intrinsic brightness, luminosity and quantification of the of the brightness. Galactic clusters have elliptical dwarf and circular dwarfs with little mass of almost solar masses.

Galactic clusters are 3000 light years (at minimum) mostly compact and associated with black materials of massive black holes if they are big. Globular clusters barely reach a million solar masses. The presence or absence of dark matter alternates through the globular cluster based on the size of galaxies (Al-Biruni 43).

They lack SMBH although they have intermediate dark masses of holes that are about 75 light years in radius. Globular constellations are constituents of halo galaxy and they behave like satellite galaxies. In conclusion, Globular clusters consist of single generation stellar population. On the other hand, galactic clusters consist of distinct and intermediary stellar population.

The cluster method explains that masses of galaxies are gotten from the distribution of x-ray releasing gases, if the gas is in hydrostatic equilibrium. The mass of the galaxies are affected by sound crossing time, gravitational potential, magnetic fields and gas pressure.

According to Sarazin (“Total masses and mass distributions in clusters-the hydrostatic method” 87), the masses range according to the motion of the varying factors that show significant dynamic variables and cooling flow. Ultimately, mass distribution of the factors causes the mass of the galaxies as narrowed down in the formula below.

mass distribution of the factors causes the mass of the galaxies

By the year 1920, Shapley discovered the scale of the galaxy, citing that the sun was fifty thousand light years from the galaxy centrality. To be precise, Harlow Shapley identified the radius of the galactic disk to be about one hundred and fifty thousand light-years. Ultimately shapely computations that interstellar substances take in the light form stars, therefore, influencing the effects of stellar illumination (Seeds 76). Ultimately, the values have been settled to about thirty thousand light years for the distance of the galactic cluster as well as the one hundred thousand light years- for the diameter.

On the other hand, Harlow Shapley failed to realize the relationship of the scale to the universe. Shapley employed various methods to come to his discovery. Sharply used telescopes in the year 1915, 1916 and 1917 and realized the globular clusters in the plane of the Milky Way were compact.

Shapley derived a conclusion that the solar system was about fifty thousand light years which away from the center. As such, Harlow Shapley narrowed down to the conclusion that the solar system is not at the center of the galaxy having a diversion of fifty thousand light years (NASA 2).

Compare the differences between galactic and globular clusters

The formation, stellar population and definition of the two clusters is different. A galactic cluster came from the primordial gases and dusts in the early bulge of the massive black hole created in the universe. The globular cluster may have been formed together with the circle of light. Galactic clusters have elliptical dwarf and circular dwarfs with little mass of almost solar masses. Galactic clusters are 3000 light years (at minimum) mostly compact and associated with black materials of massive black holes if they are big.

Globular clusters barely reach a million solar masses (McLuhan 123). The presence or absence of dark matter alternates through the globular cluster based on the size of galaxies. They lack SMBH although they have intermediate dark masses of holes that are about 75 light years in radius. Globular constellations are constituents of halo galaxy and they behave like satellite galaxies. In conclusion, Globular clusters consist of single generation stellar population. On the other hand, galactic clusters consist of distinct and intermediary stellar population.

How does the use of H II regions to find a galaxy’s distance differ from the use of Cepheid variables?

H II regions are characterized by the ionization of hydrogen while Cepheid variables consists of a group of bright stars that range in size and brightness. As such, Cepheid variables have a good characteristic, which associates with their period of absolute luminosity. Knowing the absolute luminosity enables the distance to be found by comparing with the apparent luminosity.

On the other hand, H II regions use the luminous areas that are actively forming stars in the galaxies. There exists a correlation between the galaxy’s absolute size and geometrical size H II illumination in the area. This makes it possible to employ the Tully fisher relation to get the distance due to the correlation of the luminosity of galaxies and velocity of H II regions.

How does the cluster method tell us the mass of galaxies?

The cluster method explains that masses of galaxies are gotten from the distribution of x-ray releasing gases, if the gas is in hydrostatic equilibrium. The mass of the galaxies are affected by sound crossing time, gravitational potential, magnetic fields and gas pressure (Govert 23). As such, the masses range according to the motion of the varying factors that show significant dynamic variables and cooling flow.

Ultimately, mass distribution of the factors causes the mass of the galaxies as narrowed down in the formula below.

mass distribution of the factors causes the mass of the galaxies

What evidence do we have that the center of our galaxy is a powerful source of energy?

In the orbits, there exist super waves. The orbits of the stars also contain supermassive dark holes at the core of the galaxy. The super waves and supermassive dark holes at the center is evidence that there is gravitational potential energy. As such, the center of the galaxy spins because of the waves releasing kinetic energy, thus powerful source of energy.

Works Cited

Al-Biruni, Ramsay. The Book of Instruction in the Elements of the Art of Astrology. London: Kessinger Publishing, 2004. Print.

Govert, Schilling. Atlas of Astronomical Discoveries. New York: Springer, 2011. Print.

Ideas of Cosmology. From Our Galaxy to Island Universes. 2012.

McLuhan, Marshall, Gordon, W. Terrence, Lamberti, Elena and Dominique Scheffel-Dunand. The Gutenberg Galaxy Making of Typographic Man G – Reference, Information and Interdisciplinary Subjects Series. Toronto: University of Toronto Press, 2011. Print.

NASA. Galaxy Clusters and How they Live their Lives. 2009.

Seeds, Michael. Horizons Exploring the Universe. New York: Cengage YouBook Series, 2011. Print.

Sparke, Gallagher. Galaxies in the Universe: An Introduction. Cambridge: Cambridge University Press, 2000. Print.

“Total masses and mass distributions in clusters-the hydrostatic method.” X-ray Emission from Clusters of Galaxies. Ed. Craig L. Sarazin. Cambridge: Cambridge University Press, 1988.