dipper@utastro.UUCP (Debbie Byrd) (09/05/84)
This is the anniversary of the discovery of the world's most recent naked-eye nova. More on Nova Cygni 1975 -- right after this. August 29 A Bright New Star in Cygnus On this date in the year 1975, stargazers all over the world were amazed to see an extremely bright "new star" in the constellation Cygnus. This new star -- or nova -- was very faint when first seen from Japan. As darkness fell all around the globe, the nova was independently rediscovered by many thousands of people. And by nightfall in the United States, the nova was the fourth brightest star in the sky! This amazing star became known as Nova Cygni 1975. Millions of people saw it -- it remained visible to the naked eye for several weeks. Most astronomers agree that this object was probably like other novae -- a double system in which a very small, massive white dwarf star rips matter from its companion star. This stolen matter piles up on the white dwarf. When it reaches a critical mass -- about one-ten-thousandth the mass of our sun -- a gigantic explosion occurs. For a few days or weeks, the star is a million times brighter than normal -- later it fades again. Theory predicts that the whole process should be repeated about two thousand years later -- although no one has observed long enough to see any star like Nova Cygni explode twice! It's still a mystery how the white dwarf manages to rip so much matter from its companion star -- about a thousand times more than predicted. In fact, the white dwarf is so good at stealing matter from its companion star that the companion should be completely cannibalized in only about 50 million years -- a very short time in astronomical terms! Script by Joe Patterson. (c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin