Charles Packard

Ted Coskey

Astronomy 100

April 27, 2009




††††††††††† After plotting the nearest and brightest stars on the HR Diagram which was made using the star spectrum between O to M horizontally and then absolute magnitude vertically, I was able to distinguish between White dwarf, Giant, Super giant, and Main sequence stars.The HR Diagram does not show the diameter or how big the stars are but just the absolute magnitude if you were seeing the star 10 parsecs away from earth and the sequence of the star which gives you an idea of the temperature of the star is.

††††††††††† Red dwarfs are colder stars and I was able to plot a lot of them for the nearest stars seen from earth.Then Yellow dwarfs like our sun between F and K a few less then what I plotted as Red dwarfs.Then two nearest stars plotted were determined to be White dwarfs, hotter then our sun but smaller so the absolute magnitude is a larger number. ††

††††††††††† Now for the brightest stars I plotted were between O to G in the main sequence stars. There were a few more then the other types of stars like Giants and Super giants.From O which is very hot to the B spectrum was a lot of stars being plotted which are very hot compared to our sun.Then towards the end of B to G, I noticed that this is the break between brightest stars and nearest stars in the main sequence.


††††††††††† The Super Giants are brighter because they are larger and hotter like Rigel which I plotted in Orion that is 900 light years away.Then the Giants are large but much cooler which were plotted like Betelgeuse and Antares which are 520 light years away apart of the Orionís belt.

††††††††††† In conclusion the HR diagram shows the intensity of brightness if the star where located 36 light years away (10 parsecs) and the temperature or star spectrum but not the size in diameter of the star.But because we know Super Giants are hot and big just like Red Giants which are also big but cooler, we can look at the diagram and estimate.Like White Dwarfs as hot as a super giant but about the size of earth so they are dimmer between ten to fifteen absolute magnitudes.†† The HR diagram is a good tool to cluster stars and estimate distance based on absolute magnitude and apparent.†††††††††††† ††††