By studying the light of a star we can not only learn what they are made of but can accurately deduce their temperature, size and even age. We can even find some stars which vary in size. These variable stars as they are known shrink and grow over a very regular period and the variation in their brightness can be clearly measured. There are other variable stars whose brightness variation is driven by other processes for example members of binary star systems can dip in brightness as one star passes in front of another.
These systems where more than one star makes up the tiny speck of light are surprisingly common in the Universe. Binary or multiple star systems as they are called can be just two or maybe even four or more individual stars all orbiting around a common centre of gravity. These stellar systems make up an estimated 50% of all stars in the sky and by studying their motion around each other, we can work out a number of physical characteristics.
It may come as a surprise to learn that stars don’t last forever. Our Sun was formed about 5 billion years ago and we look at the process that led to it’s formation in the Nebula pages. It turns out then, that stars are born and die. The mass of the star determines the manor of its eventual demise. For stars like our Sun, they will die in a relatively quiet manor loosing its outer layers to space because it can no longer hold on to them. This is the fate that awaits our Sun in about 5 billion years time. The core of the star will be left behind often as a rapidly cooling and fading white dwarf.
For stars more massive, they end their lives in a much more explosive manor, blowing themselves to pieces. These supernova events mark one of the most violent explosions in the Universe and, one star going supernova will often outshine all the stars in a galaxy put together. Not much is left behind of the original star other than the super compressed core which, depending on the stars mass, will either become a neutron star or maybe even a black hole.
Mark’s Observing Tip
Its quite easy to pick out the colours of the stars with the naked eye and variable star brightness can be observed quite readily. For binary or multiple stars, you will often need a telescope to help separate the individual stars. The dimeter or aperture of a telescope will determine what level of detail can be seen, this is called its resolution. Find out the resolution of your telescope in arc minutes or arc seconds and you will be able to see if you will be able to separate the individual stars (their separation is specified in same units).