Starburst Galaxies

The universe is filled with galaxies, which are themselves filled with stars. At some point in its life, each galaxy bristled with star formation in vast clouds of hydrogen gas. Even today, some galaxies seem to have more than the usual amount of star birth activity and astronomers want to know why. There were so many stars being born in some galaxies in earlier times that they probably looked like cosmic fireworks bursts. Astronomers refer to these hotbeds of star birth as starburst galaxies. Key Takeaways: Starburst Galaxies Starburst galaxies are galaxies where high rates of star formation has occurred very quickly.Nearly all types of galaxies can undergo starburst events if conditions are right.Astronomers know that starburst galaxies are often involved in mergers that mingle stars and gas. Shock waves push the gas, which sets off the starburst activity. Starburst galaxies have unusually high  rates of star formation, and those bursts last for a short time during the galaxys long life. Thats because star formation burns through the gas reserves of the galaxy very quickly. It is likely that the sudden burst of star birth is triggered by a specific event. In most cases, a galaxy merger does the trick. Thats when two or more galaxies mesh together in a long gravitational dance and eventually meld together. During the merger, the gases of all the galaxies involved are mixed together. The collision sends shock waves through those gas clouds, which compress the gases and set off bursts of star formation.   Properties of Starburst Galaxies Starburst galaxies are not a  new type of galaxy, but rather simply a galaxy (or mingled galaxies) in a particular phase of their evolution. Even so, there are some properties that show up in most starburst galaxies: a very rapid star formation rate. These galaxies will produce stars at rates well above the average rate of most regular galaxies; availability of gas and dust. Some galaxies may have higher than normal star-formation rates simply due to their high volumes of gas and dust. However, some starburst galaxies do not a have the reserves to justify why they would have such high rates of star formation, so mergers may not be the only explanation;star formation rate is inconsistent with the age of the galaxy. The main point is that the current rate of star formation could not have been constant since the formation of the galaxy given its age. An older galaxy simply wouldnt have enough gas left over to keep up starbirth action for billions of years. In some starburst galaxies astronomers see a sudden burst of star birth, and often the explanation is a merger or chance encounter with another galaxy. Astronomers sometimes also compare the rate of star formation in a galaxy relative to its rotational period. If, for example, the galaxy exhausts all of its available gas during one rotation of the galaxy (given the high star formation rate), then it can be considered a starburst galaxy. The Milky Way rotates once every 220 million years; some galaxies go much slower, others faster. Another widely accepted method to see if a galaxy is a starburst is to compare the star formation rate against the age of the universe. If the current rate would exhaust all of the available gas in less time than 13.7 billion years, then its possible that a given galaxy may be in a starburst state.   Annotated image showing dazzling eyelid-like features bursting with stars in galaxy IC 2163. A tsunami of stars and gas triggered by a glancing collision with galaxy NGC 2207 (a portion of its spiral arm is shown on right side of image). ALMA image of carbon monoxide (orange), which revealed motion of the gas in these features, is shown on top of Hubble image (blue) of the galaxy. M. Kaufman; B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble Space Telescope Types of Starburst Galaxies Starburst activity can occur in galaxies ranging from spirals to irregulars. Astronomers who study these objects classify them into sub-types that help describe their ages and other characteristics. Starburst galaxy types include: Wolf-Rayet galaxies:  defined by their ratio of bright stars that fall into the Wolf-Rayet classification. Galaxies of this type have regions of high stellar wind, driven by the Wolf-Rayet stars. Those stellar monsters are incredibly massive and luminous and have very high rates of mass loss. The winds that they produce can collide with regions of gas and drive rapid star formation.Blue compact galaxies:  low mass galaxies that were once thought to be young galaxies, just beginning to form stars. However, they usually contain populations of very old stars. That usually is a good clue that the galaxy is quite old. Astronomers now suspect that blue compact galaxies are actually the result of mergers between galaxies of varying ages. Once they collide, starburst activity ramps up and lights up the galaxies.Luminous infrared galaxies:  dim, hidden galaxies that are difficult to study because they contain high levels of dust that can obscure observation. Typically infrared radiation   detected by telescopes is used to penetrate the dust. That provides clues to increased star formation. Some of these objects have been found to contain multiple supermassive black holes, which can shut down star formation. The increase in star birth in such galaxies has to be the result of a recent galaxy merger. Cause of Increased Star Formation Although the merger of galaxies is pinpointed as the main cause of star birth in these galaxies, the exact processes are not well understood. Partially, this is due to the fact that starburst galaxies come in many shapes and sizes, so there may be more than one condition that leads to increased star formation. However, for a starburst galaxy to even form, there must be lots of gas available to generate the new stars. Also, something must disturb the gas, to begin the gravitational collapse process that leads to the creation of new objects. Those two requirements led astronomers to suspect galaxy mergers and shock waves as two processes that can lead to starburst galaxies.   Centaurus A galaxy has a massive black hole at its heart that is actively gobbling up material. The actions of such active galactic nuclei may play a role in starbursts in galaxies.   ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray) Two other possibilities for the cause of starburst galaxies include: Active Galactic Nuclei (AGN): Virtually all galaxies contain a supermassive black hole in their core. Some galaxies appear to be in a state of high activity, where the central black hole is ejecting massive amounts of energy.  There is a great deal of evidence to show that the presence of such a black hole can dampen star formation activity. However, in the case of these so-called active  galactic nuclei, they can also, under the right conditions, trigger rapid star formation as the accretion of matter in a disk and its eventual ejection away from the black hole can create shockwaves that could trigger star formation.High supernova rates: Supernovae are violent events. If the rate of explosions increases due to the presence of a very high number of aging stars in a compact area, the resulting shockwaves can begin a rapid increase in star formation. However, this such an event to occur the conditions would have to be ideal; more so than in the other possibilities listed here. A supernova can push clouds of nearby gas around spur limited amounts of starbirth. This supernova is shown in a Hubble Space Telescope view of the Crab Nebula supernova remnant. NASA/ESA/STScI Starburst galaxies remain an active area of investigation by astronomers. The more they find, the better scientists can describe the actual conditions that lead up to the bright bursts of star formation that populate these galaxies.   Edited and updated by Carolyn Collins Petersen.

What Causes Delinquent Behavior Essays - 931 Words

It is hard for anyone to understand why people commit heinous crimes. We as human beings are all capable of committing or engaging in delinquent behavior. What stands in the way of a person that decides to engage in deviant behavior or to choose not to commit crimes at all. We may never truly know or understand the real reasons behind why certain people engage in delinquent behavior. Early philosophers and scientists studied the Criminal Justice System and the behavior of criminals using different forms of theories, which in turn, lead to the Classical School and the Positive School. We all use theories in our everyday life. We make assumptions about certain things, that in turn allow us to form a kind of theory or thought. We gather†¦show more content†¦The way that people use these terms depends greatly on how they understand them and how they are using them at a given time, theories help us understand our social norms. Having a good theory is to be able to understand all the areas that the theory deals with, it is not only easier on you as the researcher, but it is also easier for you to understand what other theorist was writing about. One of the oldest conception about the Criminal Justice System and crime emerged out of the eighteenth century which is best known as the Classical School of criminology. During this time period paved a way for some basic ideas about the operation of the criminal justice system and the processing of sentencing. The Classical School was not interested in studying the criminals but more focused on lawmaking and the legal process. Best known for there works and were the most influential during this time was philosophers Jeremy Bentham and Cesare Beccaria. From the Classical School concept they believe that people have the free will in making their own decisions and that punishment can be a deterrence to others, as long as the punishment was swift and fit the crime. The school saw two forms of deterrence specific and gen eral. Specific deterrence is giving a offender the most sever punishment or applied just enough pain to deter them from repeating. General deterrence was applied to show potential offenders thatShow MoreRelatedIntroduction: There are many theories that attempt to explain the phenomenon of juvenile1000 Words   |  4 Pagesthat attempt to explain the phenomenon of juvenile delinquency and the factors that cause it. There is, and has been, a great amount of young people who engage in delinquent behavior throughout the nation and worldwide. What exactly is the catalyst that incites these young people to commit crime and stray from the ethical norm established in society? Are all youth susceptible to the temptation of deviant behavior or is it just some? 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Culture and Traditional Gambian Dress Free Essays

A)In a paragraph, describe the acculturation process that the author experienced and explain how her cultural identity changed. Catherine Pigott came from a Western background. In Africa, she experienced a dramatically different culture. We will write a custom essay sample on Culture and Traditional Gambian Dress or any similar topic only for you Order Now At first, it must have been very difficult. There was little about her that appealed to the Gambian sense of femininity. She was far too thin by those standards. Consequently, she could not dance as they danced, dress as they dressed, or eat with the relish and gusto becoming of a Gambian woman. Frankly, she was too thin. Her slim physique represented everything synonymous with poverty, drought and starvation. Her body was a cause of sadness for those who looked upon her. If she were to remain in Gambia, she would need to adapt to these rather foreign cultural expectations. Her new lady friends insisted she gain more weight, and made it a priority to help Catherine accomplish that goal. Pigott began to understand that â€Å"big truly is beautiful† in this part of Africa. Everyone looked favourably on a woman carrying weight on her hips and thighs. A woman is beautiful if she has a round stomach and heavy, swinging breasts. This was not Catherine’s cultural ideal. In fact, she had difficulty eating as they did; for her, to eat with such delight and abandon was unattractive. Nevertheless, with time she gained weight, and slowly began to believe in Africa’s beauty image. She believed she was becoming more beautiful; she let go of the panic, shame and guilt-ridden resolves regarding her weight and eating habits. One day she clothed herself in traditional Gambian dress and made her way to the shops. As she returned, she placed her newly purchased items on her head, and made her way back home, slowly, swinging her hips in the manner of the natives. She was transformed. Now, when she looked upon the skinny European tourists, she did not see an ideal; she saw something more skeletal than slim, lacking in shape and substance. Her ideal had changed. After only one year Catherine returned home. She was happy and comfortable with her body, but her family had nothing nice to say about her new weight. Pigott returned to a land where fat is feared and despised. Before one month had elapsed she was already back at the gym, yearning to be slimmer and more fit. She was unhappy again; she had lost her Gambian freedom. Catherine’s process of adopting the cultural traits and social patterns of Gambia was difficult, but it was genuine. By the time she left Africa, she was comfortable with her body; she had adopted an entirely new perspective. Unfortunately, she would revert to her older, less fulfilling, cultural ideals after returning home. How to cite Culture and Traditional Gambian Dress, Papers

Debut Albums and Silently Alongside Bruiser free essay sample

Growing up in the deep south I would be In my grandparents yard reintegrate new born puppies. Going to the cold Smokey Mountains I would go to The rushing falls running. On a snow-covered Christmas day my dad and I were ornithology the deserted downtown. Doing laps and laps on frightfully frosty winter nights Signing up for a new sport, scared but ready. Running. Sounds of squirrels, and creeks flowing in trails where I was silently Running Connected myself with nature and who I am deep down Inside. Unseen Shadow Worry hung over the room like a soupy fog, s silence was the only sound.A dark, undefined shadow dashed before my eyes. Carefully, I crept behind the velvet-red chair, hoping to become unseen. Thick, smoke-scented alarm began to shake my senses, Left.. . Was a dark, defined shadow of dust-like ash.. Floating low in dense fog. The not so Legally blonde Like her blonde hair, she bleaches out her past with little, yet loud lies. We will write a custom essay sample on Debut Albums and Silently Alongside Bruiser or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Pretty pink on the outside but, blistering black controls inside. She walks slowly, silently. .. Alongside Bruiser, her aggressive black pit-bull, looking for her next victim.Sneaking behind her ex, A sly smirk screams on her face as she does the bend-and-shoot. Now being the defendant, she is questioned by a pink mirror-like image. Opening the door, the scent of sugar filled my face with a smile. Gingerbread men danced throughout Grandmas kitchen Presents hid beneath the pine-like tree, ready to be sent. . Looking out the frosty window, a familiar ghostly figure glanced at me Now, everyone was eagerly eating those dancing gingerbread men Cross Country I can hear the beat of feet hitting the ground. I can hear roaring voices that irritate some ears.