History Talk 3. Do you like this video? Play Sound. Real World article written from a Production point of view. This article or section is incomplete This page is marked as lacking essential detail, and needs attention. Information regarding expansion requirements may be found on the article's talk page.
Feel free to edit this page to assist with this expansion. Universal Conquest Wiki. Test Part 1. Test Part 2. Test Part 3. Stars that are much more massive than the Sun continue the fusion process until they reach a point where the core collapses. The outer layers also collapse onto the core and then rebound out to space in a catastrophic explosion called a supernova.
When stars die, all the elements they created in their cores are scattered to space, to become part of interstellar clouds of gas and dust. Those chemical elements are seed materials for new generations of stars, planets, and life. Astronomers sort stars into categories according to their spectral characteristics — that is the information contained in the light they radiate.
For example, O- and B-type stars are blue-looking and are generally among the hottest stars — between , Kelvin. A-type stars are blue-white and have temperatures around 9, K. The F-type stars are white and are no hotter than 7, K.
The G-type stars are yellow-white and around 5,, K. At the cooler end of the spectrum, the K and M stars are orange and red, respectively, and range from 5, to 3, degrees Kelvin. The coolest stellar objects are the R, N, T, and Y stars, which include the brown dwarfs objects too hot to be planets and too cool to be stars. Astronomers further classify stars by such characteristics as their rotation rates, and metallicity how many elements heavier than hydrogen and helium they contain.
Stars are plotted on a color-luminosity chart called the Hertzsprung-Russell Diagram. The stars in their hydrogen-burning phase fall into a curving line called the Main Sequence. White dwarfs, giants, and supergiants all fall outside this sequence, showing that they are fusing other elements and thus are in advanced stages of evolution.
The most famous star in our sky is the Sun, the source of the heat and light that powers the solar system. Then, it will start to fuse helium, which will heat up the Sun and cause it to expand.
The Sun may form a planetary nebula, and eventually will shrink down to become a white dwarf. It will continue cooling for another billion years. The closest stars to our Sun are in the Alpha Centauri System. They are visible mainly from the Southern Hemisphere and the most southerly parts of the Northern Hemisphere.
These stars lie 4. The brightest is Alpha Centauri, which is a double star containing a G-type main-sequence star similar to the Sun. Its companion is Alpha Centauri B, and is a K-type star somewhat dimmer than the Sun and with less mass. The brightest star in our night sky is called Sirius and is also the brightest star in the constellation of Canis Major, the Big Dog. It lies 8. Sirius is the brighter member of a two-star system; its companion is called Sirius B.
It is twice the mass of the Sun and over 25 times more luminous. Sirius B is slightly less massive than the Sun and is a dim white dwarf star. Sirius was used by ancient people as a way to mark the change of seasons and as a navigational aid for long sea voyages. Astronomers theorize that the widest a star can be is just under 2, solar radii. There are a few stars that reach that size, including one called UY Scuti.
UY Scuti is a variable star, which means that its brightness varies over time. Another way to measure a star is by its mass, which is expressed in terms of solar mass. We ship to Canada. Shipping costs are the same for Canada as USA. Cancellation Information If you are not completely satisfied and would like to cancel your model subscription please contact customer service at or via email at customerservice deagostiniusa. View More Products. View Details. Remove from Wishlist. Add to Wishlist.
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