Supernova: Progenitor of life?
Published 12:00 am Wednesday, December 10, 2014
A supernova (the plural is supernovae) is the explosion of a star that, for a brief time, can outshine all other stars within a host galaxy. The subject is often discussed as a possible explanation for the bright Star of Bethlehem, of special significance in Christianity during the month of December. Science today has not found data to support the appearance of that star.
The Crab Nebula, also known as M1 in the constellation Taurus, is a supernova remnant created by a supernova explosion in 1054 AD. Bright enough to be observed in daylight, the explosion was seen and recorded by the Chinese at the time. This sighting is a testament to the gargantuan amount of energy released.
Supernovae can come about by two principal means. One is the sudden reignition of nuclear fusion in a white dwarf star. Material may be gravitationally pulled from a nearby companion star, fall onto the surface of the dwarf and initiate the explosion. It is also possible for this method to happen as a result of merging dwarf stars. The second method involves collapse of the core of a very massive star, which can release enough gravitational potential energy to create a supernova explosion. There are a number of other suggested mechanisms that can generate a supernova; however, detailed explanations go well beyond the scope of this article.
Supernova explosions are of particular significance to all life. All high-mass elements, those heavier than iron and nickel on the periodic table of elements, are created by these gigantic explosions. Moreover, the interstellar medium is thusly seeded with elements, both relatively low and high mass, that are necessary for life. The progenitors of life are spread everywhere throughout the universe. The last observed naked-eye supernova in the Milky Way, our home galaxy, was Kepler’s Star, seen in 1604. Occurring in the constellation Ophiuchus, the explosion originated about 20,000 light-years from Earth. It is estimated that three supernovae explosions happen in the Milky Way over periods of about a hundred years. Naked-eye examples are quite rare.
— Kent Fairfield is a volunteer with Pine Mountain Observatory and a lifelong amateur astronomer. He can be reached at kent.fairfield@gmail.com. Other PMO volunteers also contributed to this article.