Take a look at the image & caption below it about supernova explosion.It says the white dwarf star is spreadin?

g its gas as far as 70 Light Years.





http://antwrp.gsfc.nasa.gov/apod/ap05122鈥?/a>








I know that nearest star to us lies within 4.2LY.so the stars within the range of 50-100LY RANGE FROM eARTH WILL reach up to us to take a smell of the supernova remnant gases.


Just how harmful they were in case we mate with such disaster in our lifetime?And how a star after explosion spreads its gas at distances so large in magnitude [70LY]?


can we able to here the sound produced during such explosions?


[i know that the star has nearly perfect vacuum around as its surrounding, so no scope for sound propagation, but still is any other advance method developed to do so]Take a look at the image %26amp; caption below it about supernova explosion.It says the white dwarf star is spreadin?
Most models agree that if a star went supernova within about 100ly of the Earth, the ozone layer would be exposed to such bombardment by high energy x and gamma rays that it would not be able to protect us from the deadly radiation coming from out own star and the base of the food chain would die off (there are some models that suggest the event would have to happen much closers, perhaps 25ly).





The closest star to Earth that will one day go supernova is Spica in constellation Virgo at the distance of 260 ly. We can conclude that there is no danger for life on Earth from the regular type of supernovae.





However, massive stars are not the only ones we can explode. There are other types of supernovae (namely type I) that can be created in a binary star system when one of the stars matures faster and turns into a white dwarf. As the second star enter the red giant phase and expands, the white dwarf could accrete matter from the red giant up to when it grows to about 1.44 solar masses at which point the outward pressure of electron degeneracy cannot prevent the white dwarf from collapsing under its own gravity. As it collapses the temperature grows tremendously and because the electron degeneracy is independent of the temperature there is nothing to stop the collapse ... the temperature grows until it reaches a point when almost all material of the white dwarf undergoes thermonuclear fussion in matter of seconds and the released energy is big enough to unbind the white dwarf in a supernova.





There is some chance that the white dwarf in the Sirius system (Sirius B) could on day go through this process once Sirius A (the brightest star in the night sky) enters the red giant phase. Most models, however, suggest that the conditions aren't right, namely, Sirius B is too far off from Sirius A to feed at the necessary rate. Also, as far as we know there are no other condidates for type I and type II (for that matter) on our vicinity.Take a look at the image %26amp; caption below it about supernova explosion.It says the white dwarf star is spreadin?
The caption tells part of the story. You have to click the links for the whole story.





Briefly, if a white dwarf is part of a binary system, gas from a companion star can accumulate on the surface of the white dwarf until enough is there to form a critical mass, and the hydrogen on the surface fuses into helium in an enormous detonation across the entire surface of the star.