HR Diagram and Variable Stars Lab RevMar2016 Mailings Review Vievw Heading Norma
ID: 292307 • Letter: H
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HR Diagram and Variable Stars Lab RevMar2016 Mailings Review Vievw Heading Normal Background Part 1: The HR Diagram The Hertzprung-Russell, or HR, Diagram is a chart on which stars are organized by their luminosity and temperature. You can find example charts and more information at daviddarling.info (http://www.daviddarling.info/encyclopedia/H/HRdiag.html); at The University of Califomia (http:l/casswww.ucsd.edu/archive/public/tutorial/HR.html); at Wikipedia (http://en.wikipedia.org/wiki/Hertzsprung%E2%80%93Russell diagram); and in your lecture textbook. The vertical (y) axis of the diagram is the Luminosity, or energy emitted per time (power) sent out by the sun. Sometimes this axis may be labeled as Absolute Magnitude, or how bright a star would appear to someone exactly 10 parsecs away Absolute magnitude is directly related (directly proportional) to luminosity: if one goes up, the other goes up. The horizontal (x) axis is Temperature, which increases toward the left of the diagram. The axis may also be labeled by Spectral Class of the stars. The spectral classes go in order by temperature from the hottest stars o, through B, A, F, G, K, to M, the coldest stars. On some diagrams, you will see each of these classes divided up into subclasses 0 through 9. The Earth's Sun is a G2 star. Questions Part 1: The HR Diagranm Study the HR Diagram here (https://icogt.net/spacebook/h-r-diagram/) and play with the Star in a Box (http://Icogt.net/siab/). This information will help you to answer some of the questions below. (Alternately, check out the links in the Background information above, an alternate but reliable internet source that you may choose, and the textbook from your current or previous Astronomy lecture course.) 1. What type of star is oldest: a red giant, a main sequence star, or a white dwarf? Which of the following stars has the greatest luminosity: our sun, the red supergiant Betelgeuse, or the white dwarf Sirius B?Explanation / Answer
Ans 1) Out of main sequence star, white dwarf and red giant, white dwarf is the oldest. In the life cycle of a star, it is initially a main sequence star, then it becomes a red giant which is followed by planetary nebula and then finally leading to White dwarf. therefore the white dwarf is the oldest.
Our sun has the highest luminosity out of the three.
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