Experimental Analysis: The Formation Of The Milky Way

The Formation of the Milky Way
By Nathanael Roybal; Geological Sciences
ABSTRACT

The Milky way is a band of light that has millions of stars that are combined together and that spans 100,000 light years away. They say the Milky Way is about 14 billion years old. How they figured this out by measuring the ages of each star. They have found trace elements of hydrogen and helium so we know that the Milky Way was formed an early in the history. Another good way to find the age of the stars in the Milky Way is measuring thorium because it has a half-life of 14 billions years after 14 billion the thorium should decay in another element. The formation of the Milky way starts by observations concerning chemical abundances in stars and gas using nucleosynthesis
calculations. they measured star formation rate (SFR), the initial mass function (IMF) to find a good model of chemical evolution can allow us to impose constraints on such quantities.

Introduction

The Milky Way is a band of light, the combined glow of millions of stars, which outline the flat disk of our Milky Way Galaxy. The Milky Way is the gigantic cluster of stars, which spans 100,000 light years, and contains hundreds of billions of stars. Astronomer Chris Sneden from the University of Texas said it is about 14 billion years old (McDonald Observatory, 2011). Astronomers arrived at this age by measuring the age of a single star. The galaxy is younger than its oldest stars, so this technique yields a minimum age for the Milky Way. Astronomers determined the star’s age by measuring its chemistry. They found that it contains traces elements of hydrogen and helium, the two lightest elements. That shows us that the star must have formed early in the history of the Milky Way because heavier elements were formed inside stars then expelled into space that was fused into new stars. One of the most important tracers of the star’s age is a radioactive element called thorium. Stars that contain about half of thorium are expected to have a half-life of 14 billion years. In 14 billion years, half the star’s thorium should have turned into other elements. Since half of the thorium has disappeared, astronomers deduce that the star is about 14 billion years old and so is the Milky Way.
Formation of the Milky Way
So we know how old the Milky Way is now I am going to start talking about the Formation of Milky Way.The formation and evolution of the Milky Way galaxy comes, on one side, from observations concerning chemical abundances in stars and gas and, on the other side, from the continuous improvement of stellar nucleosynthesis calculations (Chiappini et al, 2001).
There are some important quantities relevant to the chemical evolution of the Milky Way, such as the star formation rate (SFR), the initial mass function (IMF), and gas are still poorly constrained. However, a good model of chemical evolution can allow us to impose constraints on such quantities (Chiappini et al, 2001). In particular, a good chemical evolution model should be able to reproduce observables larger in number than the number of adopted free parameters. Among the observables there are in the center with the consequent formation of the bulge. During the second episode, a much slower infall of primordial gas gives rise to the disk with the gas accumulating faster in the inner than in the outer regions. In this scenario the formation of the halo and disk are almost completely dissociated although some halo gas falls into the disk. This mechanism for disk formation is known as “inside-out II scenario, and it is quite successful in reproducing the main features of the Milky Way (CMG97) as well as of external galaxies especially concerning abundance gradients” (Chiappini et al, 2001). That how was the Milky Way was
formed and I going to start talking about the Star Formation.

Star Formation in the Milky Way

Star formation encompasses the origins of stars and planetary systems, but it is also a principal agent of galaxy formation and evolution, and hence a subject at the roots of astrophysics on its largest scales.
The past decade has witnessed an unprecedented stream of new observational information on star formation on all scales, thanks in no small part to new facilities such as the Galaxy Evolution Explorer (GALEX), the Spitzer Space Telescope, the Herschel Space Observatory, the introduction of powerful new instruments on the Hubble Space Telescope (HST), and a host of groundbased optical, infrared, submillimeter, and radio telescopes. These new observations are providing a detailed reconstruction of the key evolutionary phases and physical processes that lead to the formation of individual stars in interstellar clouds, while at the same time extending the reach of integrated measurements of star formation rates (SFRs) to the most distant galaxies known. The new data have also stimulated a parallel renaissance in theoretical investigation and numerical modeling of the star formation process, on scales ranging from individual protostellar and protoplanetary systems to the scales of molecular clouds and star clusters, entire galaxies and ensembles of galaxies, even to the first objects, which are thought to have reionized the universe and seeded today’s stellar populations and Hubble sequence of
galaxies.

Conclusion
The milky way is about 14 Billions years old and how scientist found that out by measuring the

REFERENCES CITED
Chiappini, C., Matteucci, F., & Romano, D. (2001). Abundance Gradients and the Formation of the Milky Way. The Astrophysical Journal,554(2), 1044-1058. doi:10.1086/321427.
Kennicutt, R. C., & Evans, N. J. (2012). Star Formation in the Milky Way and Nearby Galaxies. Annual Review of Astronomy and Astrophysics,50(1), 531-608. doi:10.1146/annurev-astro-081811-125610.
McDonald Observatory. (April, 2011) “The Milky Way.” The University of Texas at Austin. Retrieved from file:///Users/nathanaelroybal/Desktop/TheMilkyWay.pdf