Astronomy?

Question

How can you tell relative temperatures of stars by the color of the star?

Why do some gaseous clouds of hydrogen glow green?

Answer 1

Based on the knowledge of the stars brightness and color, what would you assume about the stars relative temperature? List the stars from coolest to hottest.

The applet in this exercise allows you to look at a virtual light bulb capable of a wide range of temperatures. The applet screen is broken into four parts. The bottom right is your temperature control. You can use the slider bar, or type the temperature in Kelvin. The bottom left is the light bulb. The upper right is what you see when you split the light with a spectral grating or prism. The upper left is a plot of brightness versus the wavelength of the light. Notice that the visible part of the spectrum is the part of the plot between the red and blue lines. To the left of the red line is infrared and radio light. To the right of the blue line is ultraviolet light.

Many people think that white hot should be hotter than blue hot. Maybe this goes back to our ancestors sitting around a fire, and seeing the hottest parts of the flame being white. However, it actually takes a pretty hot source, hotter than we get with charcoal or wood, to create a blue light. Blue stars have a surface temperature of 10000 K or higher.

Red light is the low energy end of the electromagnetic spectrum. Blue light is the high energy end. So, hotter (higher energy) objects will produce bluer light. Light that is "in between" will get a mixture of all visible colors, and since when you combine all different colors of light you get white light, white stars are stars of an "in between" temperature.

http://www.shodor.org/refdesk/Resources/Activities/ColorsOfStars/index.php

Answer 2

Temperature is related to color. A red hot iron is cooler than a white hot iron. Look up "color temperature" on wikipedia or whatever.

It is oxygen that glows green in gaseous clouds in space. Hydrogen glows red.

Answer 3

Did you ever see a candle go out by itself? Did you notice how the wick changed color as the candle died out? It's the same thing with stars.

As for why some gaseous clouds of hydrogen glow green, maybe they have enough methane in them to give off the green color?

Answer 4

A star's color can give clues to an important property of a star: its average temperature. All objects give off "thermal radiation" - light waves emitted from the random motions of atoms inside the object. As the atoms heat up, they move around more, and thus give off more radiation. As atoms heat up and move faster, the peak wavelength of their thermal radiation changes.

Answer 5

hotter stars burn more blue-white. cooler stars burn more dark red. Green ones are in the middle.