Stars, Stars & More Stars

There are 6000 stars visible to the naked eye. Some stars seem to sparkle or twinkle. This 'twinkle' is caused by the atmosphere around our earth, blurring our sight path. Now we send orbitting telescopes outside our atmosphere to avoid this problem.

These other 'suns' are bourn out of clouds of gas. We don't need to visit other stars to find out what they are made of. With the study of starlight we can decode informatin such as temperature, chemical makeup, magnetic fields and velocity.

With the force of gravity, stars will contract until the heat & pressure are so intense that a nuclear reaction takes place and the hydrogen transmutes into helium. These nuclear reactions generate the force needed to halt the star's contraction. Heavier stars will later turn helium to carbon and carbon to other heavier elements like iron. The life and death of a star will depend on its initial mass.

Some stars form a binary star system. Like two stars beginning to dance, they revolve around each other. This process, usually has one star being sucked up by the more powerful one. Still other stars may even form triangular star systems.

Above: About 1,600 light-years away, in a binary star system fondly known as J0806, two dense white dwarf stars orbit each other once every 321 seconds .

Image Credit: Dana Berry, NASA.

Types of Stars

Brown Dwarfs are typically less than 1/10th the mass of our sun. This type of star does not have enough mass to 'ignite' itself and therefore remains a brown dwarf for most of its life. Brown Dwarfs are difficult to spot from Earth and may well account for a large part of a galaxy's mass.

Artists rendition of a swirling brown dwarf star. Courtesy of JPL-NASA.

Above: This star has reached its so-called red giant phase, where it swells to hundreds of times its original size. Those outer layers are then captured by the gravitational pull of the denser companion. Courtesy NASA.

Red Giants (our sun is on its way to this phase) - these stars are in their later stage of development. Once this star has turned most of its hydrogen into helium, the nuclear energy production slows down and gravity becomes more dominent than the energy. The star begins to contract and starts another phase of nuclear reactions which then transmutes the helium into carbon & oxygen. The core becomes hard and fused while the outer layer is blown away as stardust by stellar winds.

White Dwarf is what remains of a Red Giant after the explosion described above. This stage in the sun's life is a much cooler and dense star, so dense that one sugar cube-sized piece weighs as much as a ton. The final phase in this star's life is called a black dwarf, even more dense and cool.

Super Giants come in two types. Type one (about 10 solar masses) fuses its core past helium and hydrogen, all the way to carbon. Gravity comes in to condense the matter, which then reacts by rebounding outwards, throwing off shock waves. This process is called a Supernova (pictured left). The core then becomes a star made of neutrons. This star transmits radio, x-ray or gamma waves. These beams (like a lighthouse in the sky) is called a pulsar.

The second type of Super Giant (30-50 solar masses) goes through a very similar process except for its final phase. Instead of becoming a neutron star, its gravity is so great that, nothing remains except for a black hole.

Both of these Super Giants types do not live as long as Red Giants. They expend their energy comparitivley quicker and they die dramatically in an explosion of cosmic proportions. The bigger they are the harder they fall.