INTRODUCTION
This work is going to talk about the Supernovas, the types of supernovas, their history and the importance for us.
We chose this topic because we think, this is a very relevant topic for us, because one of the explosions of a supernova got place to the solar system , this is the reason why we got live, we breath , we are study now. Besides we like the Astronomy and the geography because it’s exciting to study the planets that are very far away from us.
Well, as we know a supernova is a stellar explosion that creates an extremely luminous object. A supernova causes a burst of radiation that may briefly outshine its entire host galaxy before fading from view over several weeks or months. During this short interval, a supernova can radiate as much energy as the Sun would emit over 10 billion years.
Supernovas fall into two classes: those focused on relatively nearby events and those looking for explosions farther away.
Type A
One model for the formation of this category of supernova is a close binary star system. The larger of the two stars is the first to evolve off the main sequence, and it expands to form a red giant. The two stars now are sharing a common envelope, causing their mutual orbit to shrink.
The giant star then sheds most of its envelope, losing mass until it can no longer continue nuclear fusion. At this point it becomes a white dwarf star, composed primarily of carbon and oxygen. Eventually the secondary star also evolves off the main sequence to form a red giant. Matter from the giant is accreted by the white dwarf, causing the latter to increase in mass.
Type B
These events, like supernovae of Type II, are massive stars running out of fuel at their centers; however the progenitors of Types Ib and Ic have lost most of their outer (hydrogen) envelopes due to strong stellar winds or else from interaction with a companion. Type Ib supernova are thought to be the result of the collapse of a massive Wolf-Rayet star. There is some evidence that a few percent of the Type Ic supernova may be the progenitors of gamma ray bursts(GRB), though it is also believed that any hydrogen-stripped, Type Ib or Ic supernova could be a GRB, dependent upon the geometry of the explosion.
The impact of a supernova on Earth
In Earth's case, gamma rays induce a chemical reaction in the upper atmosphere, converting molecular nitrogen into nitrogen oxides, depleting the ozone layer enough to expose the surface to harmful solar and cosmic radiation. The gamma ray burst from a nearby supernova explosion has been proposed as the cause of the end Ordovician extinction, which resulted in the death of nearly 60% of the oceanic life on Earth.
Well, this is only the introduction of this relevant and interesting topic, you’ll find impressive images of the cycle of the supernovas, later you will check our presentation.
Also in this work you will find the history of the most important supernovas, and the impact that got in the earth.
And this is a little information of Supernovas:Heavyweight Remnant of a SupernovaA neutron Star is the smoking gun at the scene of a Supernova explosion. The inmense presure and heat in the Supernovas iron core at the moment of the explosion create a neutron start by forcing oppositely chargea electrons and protons so close together that they fuse to become neutrons. Inside an iron shell only a few hundred feet thick these neutrons pack together into matter so dense that a single teaspoonful could weigh a billion tons. Though no more than perhaps ten miles in diameter, the neutron star has a gravitational field at its surface 100 billion times as strong as that on the surface of the Earth.The Suepernova explosion that forms a neutron star also expels vast numbers of nearly massless particles called neutrinos, as well as an expanding cloud of dust and gas that can remain visible for thousands of years.
Well, this is our work. See you next class.
