A dwarf galaxy is, “a small galaxy composed of up to several billion stars—a smaller amount compared to our own Milky Way’s Galaxy’s 200-400 billion stars” (Wikipedia). On February 23, 2014, it was reported that two galaxies that had once orbited around the Andromeda Galaxy were merging together. The collision created a stream of stars in one of Andromeda’s dwarf galaxies, Andromeda II. Researchers then observed the stream of stars by separating them into categories and trying to analyze which could be members of Andromeda II versus those that could be “dwarf foreground stars from the Milky Way halo” (Amorisco et al, 2014, p 4). Because the stream of stars is located on an area of Andromeda II that has limited brightness, researchers found 14 “high-probability contaminants” in a region of the stream with “stars that [were] significantly more likely to belong to the Andromeda II population” (Amorisco et al, 2014, p. 4). By measuring the characteristics of the stream, researchers were able to conclude that it displayed “remnants of a merger between two dwarf galaxies…illustrating the scale-free character of the formation of galaxies, down to the lowest galactic mass scales” (Amorisco et al, 2014, p. 1).
As we discussed in lecture, galaxies are constantly colliding with each other and these collisions shape the structure and evolution of galaxies. “Andromeda II provides direct evidence for the importance of mergers even for the smallest and least luminous of galaxies” (Amorisco et al, 2014, p. 3). By discovering more evidence of galactic collisions, cosmologists and astronomers will be able to determine the effect they have on the Universe. The merging of galaxies allows for them to grow bigger—small galaxies are merged to create ...
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... is observed between the Andromeda and Milky Way satellites and has been proposed to be due to differences in the formation and/or evolution of the dwarfs” (Martin et al, 2006, p. 1989). This suggests that collisions may have other impacts on the universe depending on how often they occur and the velocities they collide with. The evolution of new dwarf galaxies is evidence that the universe is shaped by the collision of galaxies and that galaxies create big balls/clusters of stars when they hit one another. The dwarf galaxies, over time, will merge with the larger galaxies, and this cycle will contribute to the growth of the universe.
Throughout this course we have been learning about the expansion of the universe and it seems as if the universe will never stop expanding. There is so much that has yet to be discovered despite the fact that our ideas are evolving.
In the last hundred years we have made enormous progress in studying not our galaxy but ones billions of light-years away. Only a few hundred years ago our world seemed so big that there were areas of the world that had never been charted and people believed that the Earth was flat (and yes for some reason a few people still believe that today). If we continue to make progress at thus rate the universe will actually begin to seem smaller because of how much more we might know.
Two men named Harlow Shapley and Heber Curtis has a debate in 1920 that is still important today for changing how we think about galaxies. They talked about five important things. The first thing they debated was how big our galaxy, the Milky Way, is. Shapley said that the Milky Way was much bigger than we first thought, 100,000 light-years across, and that, because it was that big, it had to be the only one. Curtis said the the Milky Way was smaller than that, and that other galaxies existed past ours. They were both right and both wrong. Shapley was right about the size of the Milky Way, and Curtis was right about there being many more galaxies in the universe.
Brown dwarfs are objects in space that sit between the lines of being a star and a planet. This object is dim and hard to distinguish from low mass stars at the early stages of the dwarf’s life. They are often called failed stars because they start their life the same way as regular stars. However, in some stage, they just didn’t have enough mass gathered to generate the fusion-powered energy of a star. Scientists are certain that brown dwarfs are the missing link between stars and planets but the formations of dwarfs are still a mystery.
Only after Vesto Slipher, Hubble and others discovered in the second decade of this century that the universe was expanding, it could give a satisfactory explanation for the paradox.
An examination of the term “galactic interaction” does not immediately convey much in the way of understanding as to exactly what happens during one of these events. The problem is that the word “interaction” is fairly ambiguous, yet it must be so because two galaxies can interact in so many ways that literally every interaction we observe is a unique event (depending on how close one looks at the details). Changing the mass ratios, the angle of impact, or the morphological type of the progenitor galaxies can greatly influence the nature of the system after the interaction has played itself out, as we shall see.
It is clear that we would need further evidence and advances in physics before it will be remotely possible to know the fate of our universe. Scientists now think, and mostly agree with each other that the fate of the universe depends on three main things: the overall shape or geometry of the universe, how much dark energy it contains, and on the “equation of state”; which determines how the density of dark energy responds to the expansion of the universe.
Adam Riess and Brian Schmidt’s ambition led them to meet Perlmutter at the same conclusion. The universe’s rate of expansion is accelerating. It is being pushed apart by a mysterious dark energy. Zeeya Merali’s article “Confronting the Dark” follows Perlmutter, Schmidt, and Riess on their journey to discover dark energy. Throughout the article, we can apply of many of the basic ideas we have discussed in class.
Waller, William H. The Milky Way: An Insider's Guide. Princeton, N.J: Princeton UP, 2013. 42+. Print.
A star begins as nothing more than a very light distribution of interstellar gases and dust particles over a distance of a few dozen lightyears. Although there is extremely low pressure existing between stars, this distribution of gas exists instead of a true vacuum. If the density of gas becomes larger than .1 particles per cubic centimeter, the interstellar gas grows unstable. Any small deviation in density, and because it is impossible to have a perfectly even distribution in these clouds this is something that will naturally occur, and the area begins to contract. This happens because between about .1 and 1 particles per cubic centimeter, pressure gains an inverse relationship with density. This causes internal pressure to decrease with increasing density, which because of the higher external pressure, causes the density to continue to increase. This causes the gas in the interstellar medium to spontaneously collect into denser clouds. The denser clouds will contain molecular hydrogen (H2) and interstellar dust particles including carbon compounds, silicates, and small impure ice crystals. Also, within these clouds, there are 2 types of zones. There are H I zones, which contain neutral hydrogen and often have a temperature around 100 Kelvin (K), and there are H II zones, which contain ionized hydrogen and have a temperature around 10,000 K. The ionized hydrogen absorbs ultraviolet light from it’s environment and retransmits it as visible and infrared light. These clouds, visible to the human eye, have been named nebulae. The density in these nebulae is usually about 10 atoms per cubic centimeter. In brighter nebulae, there exists densities of up to several thousand atoms per cubic centimete...
Comparing this galaxy’s size to are own Milky Way Galaxy, which is estimated to be around 8.5*1011 solar masses large, the Andromeda Galaxy is about 20% bigger then are own. Along with this we also know that both our own galaxy and this galaxy are on a collision course. It is estimated that in around 7.5 billion years that these two galaxies will merge together in a surely violent process. It is suspected that after this a large disc or elliptical galaxy will exist in the place of the once separate galaxies.
The first person to ever observe the Milky Way was Greek philosopher, Democritus, who said the galaxy may consist of distant stars. In 1610, Galileo Galilei used a telescope to study the Milky Way and came to the conclusion that it was composed of billions and billions of faint stars. Then, in 1750, Thomas Wright c...
“Sheltered as we are by Earth's atmosphere and magnetic field, which deflect lethal radiation from space, we are like coddled children who have never ventured into a tough neighborhood” (Folger 2). Humans have been fascinated with space since the beginning of our time. Just like children and rough neighborhoods, we have tackled obstacle over obstacle to make it home again. In the end, we have a better knowledge and strength than before. The future of space exploration can assist us in answering the everlasting question of how the universe came to be. The more we explore the infinite galaxies, the more we can scientifically discover and create new technologies as science advances. As we continue to discover, we can create new fields and occupations for aspiring young students like myself.
The universe, it's vastness, how it was created, and why we are a part of it amazes and astounds many people who are constantly searching for answers. Others believe they have the answers and try to persuade people to understand their view. Others don't even think about it at all.
Astronomers believe that most galaxies consist of a supermassive black hole at the center, which attracts all constituents of galaxies such as, dust, gases (mainly Hydrogen and Helium), atoms, stars, interstellar clouds and planets to the center by force of gravity, but are not sure whether all galaxies contain a black hole in the center. Galaxies keep moving in relative motion to one another and intermittently can come so close that the force of gravitational attraction between the galaxies may become strong enough to cause a change in the shape of the galaxies, while in exceptional cases, the galaxies may collide. If two galaxies collide, they may pass right through without any effect or may merge, forming strands of stars, extending beyond 100,000 light years in space (World Book Online Reference Centre, 2005). Hence, neighboring and often other colliding galaxies induce the sha...