Facts About Stars II
Space and Astrology 6/19/11
By: Yona Williams
A globular star cluster is a spherical group of up to one million stars that are held together thanks to gravity. You will find these objects in remote locations Ã¢â‚¬â€œ mostly found around the central bulge of spiral galaxies. To learn more about stars, continue reading this article, which also touches upon the closest stars to us.
When larger groups of stars form, they are called clusters. There really isnÃ¢â‚¬â„¢t any organization to these collections of stars, as an open cluster is a loose grouping of up to about 1,000 stars. An example of these clusters include the Pleiades and Hyades. When large collections of stars are organized, they are called galaxies. The Milky Way is a spiral galaxy associated with our solar system.
What are Spiral Galaxies?
Spiral galaxies possess a central, dense region and spiraling arms, which often serve as the point where star formation takes place. There are two major parts to these common galaxies. The first is a central, flat disk that contains a dense cloud of interstellar matter. It is here that young star clusters are found Ã¢â‚¬â€œ mainly on the arms. The other part of a spiral galaxy is a central bulge (also known as a nucleus), which is home to older stars.
There are two different kinds of spiral galaxies. The "S" type is known as a normal spiral and the "SB" type is described as a barred spiral with an elongated center. The "SB" type is less common. There are many known spiral galaxies, but the best known is the Milky Way and the Andromeda Galaxy (M31).
May the Force Be With YouÃ¢â‚¬Â¦
Gravitational forces hold all groups of stars together.
The Characteristics of Stars
Thanks to nuclear fusion and nucleosynthesis, stars receive their hot and bright characteristics. Stars are considered giant nuclear reactors. At the center of a star, atoms experience a great deal of force through atomic collisions, which break apart the atoms. Their atomic structure is affected and as a result, a lot of energy is released. This causes a star to become hot and bright. The majority of stars are also affected by the conversion of hydrogen atoms into helium atoms Ã¢â‚¬â€œ known as nuclear fusion. A great deal of energy is released due to this process as well.
The Closest Star
Out of all the stars that twinkle in the sky, the Sun is the closest star to us. Trailing behind the Sun in closeness is Proxima Centauri (also known as Alpha Centauri C), which is actually the dimmest star in the Alpha Centauri system. This star measures 4.3 light-years from the Sun. Other close stars include Sirius (in Canis Major), Canopus (in Carina), Rigel Kentaurus (Alpha Centauri) (in Centaurus), Arcturus (in Bootes), Vega (in Lyra), Capella (in Auriga), Rigel (in Orion), Procyon (in Canis Minor), Archenar (in Eridanus), and Betelgeuse (in Orion).
Measurements for Stars
When people measure the brightness of an object in the sky, they calculate the apparent magnitude and absolute magnitude, which measures the inherent brightness of a celestial object. Greek astronomer Hipparchus came up with the system that rates the brightness of celestial objects in 120 B.C. Apparent magnitude (abbreviated with an 'm') measures the brightness of a celestial object as we see it from Earth.
Low numbers indicate a bright object. If the numbers are negative, it is an indicator that the object possesses extreme brightness. For example, a full moon has an apparent magnitude of -12.6. The Sun has a measurement of -26.8. Humans have the ability to view objects up to 6th magnitude without the assistance of a telescope.