Science of Stars Paper

Science of Stars Paper

Tiffany Lakes

SCI/151

September 10, 2012

Piotr Hebda

In astronomy one of the most important tools we have at our disposal is light. We can use light to our advantage in many different ways to gather information about planets and stars that we would never be able to physically reach in our lifetime. By using light we can look at a star or planet outside of our solar system and gather information like it’s composition, temperature, speed, and rotation rate. For stars we can use this information to also see what stage of life this star is in, and possibly how much longer it has in its life.

Astronomers have several instruments that they are able to use in order to determine the composition, temperature, speed and rotation rate of distant objects. In order to determine the composition of a planet they often use its density, as well as the light that is given from the object (Holladay, 2007). To determine the density of the object we would measure it’s mass and volume. Once we have determined the density of the planet we are then able to compare it’s density to planets that we already have information about such as Earth (Holladay, 2007). Next, we use spectroscopy, this I when we would use a spectrograph to view the object in space, gather light from that object and split the light into different spectra (Bennett, Donahue, Schneider & Voit, 2010).. By splitting the light we are then able to see what elements are in the object. We measure the temperature of different objects in a similar way. Different temperatures give off different colors and types of light. A hotter star will give off ultraviolet light, but will look blue-white because our eyes are not capable of seeing ultra-violet, a cooler start will seem red (Bennett et al., 2010). Last, we can also use light to determine the rotation rate and speed at which an object is moving. The light reacts much like sound, as the object is moving toward Earth and it’s light will have a shorter wavelength, leaving it blue in appearance, while moving away gives it a longer wavelength, making it red in appearance. This works the same for the rotation direction and speed of rotation. We can look at the color of the spectral lines of the object, the side that is moving away will be red while the side moving toward us will be blue. Measuring the widths of these colored spectral lines would help us determine just how fast the object is rotating (Bennett et al., 2010).

Using a Hertzsprung-Russell diagram can help us to see the relationship between stars and the properties of other stars. A hertzsprung-Russell diagram plots the stars in a graph-like diagram that will compare their luminosity