Posted: December 2nd, 2013

H-R Diagram and Spectroscopic Parallax

Description: Attention: This is a PROJECT NOT an essay!! H-R Diagram and Spectroscopic Parallax This is a three-part project. First, you will use known data to create
your own Hertzsprung-Russel (H-R) diagram. Next, you will use this diagram to estimate the absolute magnitudes of and distances to several stars in a
constellation of your choosing. Finally, you will use your estimated distances to create a side view of the constellation â in scale. Part 1: Create your H-R
diagram Data on the spectral types and absolute magnitudes of many of the nearest and brightest stars are available in the back of your book. There is
also a file containing the data for a larger list of stars available on Blackboard. Plot as many of these stars as possible on your H-R diagram, with the
spectral type along the x-axis and the absolute magnitude along the y-axis. Be sure to plot both nearest and brightest stars â neither of these two groups
is adequate to populate your H-R diagram. You may choose to plot the stars by hand, or you may use any computer plotting software you choose,
including, but not limited to the following: Microsoft Excel, IGOR, OriginLab, SigmaPlot, Mathematica, and MatLab. If you do choose to create your H-R
diagram on the computer, just make sure you consider the reminders below when setting up your plot. Remember: There are seven spectral types for
main sequence stars, and these are subdivided even farther based on the number immediately following the letter. For example, our Sun has the spectral
type âG2â. The absolute magnitude scale is logarithmic. The lowest magnitude number should be at the top of the y-axis, and the highest magnitude
number should be at the bottom of the y-axis. Once you have plotted enough stars from both categories, the location of the main-sequence should be
easy to see. Sketch a line on your H-R diagram (in a different color) highlighting its location. Using the information in your textbook, mark the right axis
with the luminosity scale in terms of the Sun’s luminosity, and the top axis with the temperature scale in Kelvins. Part 2: Plot stars from your chosen
constellation on your H-R diagram You can find use star charts of the region of the sky around each of the 88 official constellations on the website
www.topastronomer.com. These star charts include the basic information you need to use stellar parallax to estimate the distance to the stars in that
region of the sky. Go to the website http://www.topastronomer.com/StarCharts/ConstellationViewer.aspx Choose any one of the 88 official constellations,
EXCEPT Orion. Choose any ten stars to plot on your H-R diagram. Draw a picture of the arrangement of the stars you chose as they appear on the star
chart. Hover over each of the stars you have chosen to get more information about it. The two most important pieces of information for this project are
the spectral class and the magnitude. Use the spectral class to estimate the appropriate placement on the H-R diagram for each of the ten stars you have
chosen. Remember: The Roman numeral following the spectral type tells you whether the star is on the main sequence.
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 For example, our Sunâs complete
classification is G2 V, which indicates that the Sun is a main-sequence star. Roman numerals IV, IIV, III, II, and I indicate ever increasing distance above
the main-sequence line. They can be farther broken up by adding an âaâ or âbâ after the Roman numeral. The star charts will provide data on the
apparent magnitude for each star. Do not try to plot each star using the spectral class and the apparent magnitude â you can only plot stars on the H-R
diagram using absolute magnitude. Instead, read off the predicted absolute magnitude for each of the stars you chose, based on its spectral class. Make
the best estimate you can for this quantity. Estimate the distance to each of the stars you chose. In order to do this, use the absolute magnitude, the
apparent magnitude, and the formula: d i s italic tan c e space equal space 10 to the power of open parentheses fraction numerator m subscript a p p end
subscript minus m subscript a b s end subscript space plus 5 over denominator 5 end fraction close parentheses end exponent Record all of your data in a
table, including the spectral class, apparent magnitude, estimated absolute magnitude, and estimated distance. Also record the right ascension and
declination for each star. Part 3: Create a side view of your constellation Plot the ten stars you chose on a new sheet of paper as if you were looking at
them from a completely different point of view. See the diagram of the constellation Orion on page 5 of your textbook as an example. (I send this photo
as files) The estimated distance from Part 2 should be along the x-axis, and either the right ascension or the declination can be used to determine the
location along the y-axis. When you plot the stars in this way, it is simulating what they would look like to an observer who is looking at the constellation
from the side. Make sure the scale of your diagram is accurate (ie: one cm equals one parsec in distance). If one star is much more distant than all the
others, make sure your diagram reflects this fact. What do you n
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