Sunday, January 30, 2011
introductions
Please use the comment box to introduce your self to the astroBITS group. The course material can be found at http://www.noao.edu/education/astrobits/course-outline.php. Also check azastro.pbworks.com
Module 1, Assignment 1
Describe the light sources and spectra that you have projected in detail as well as any experimental difficulties you encountered in the process. How do the different light sources compare with each other?
Module 1, Assignment 2
What is the largest value you can find within the image of the sun? Let’s call these “Data Numbers” or DN value.
Comment on what you estimate is your measurement accuracy. How many significant figures are meaningful? (In other words, can you measure the diameter to an accuracy of one pixel? One tenth of a pixel? One hundredth of a pixel? None of these?)
How much fainter in DN units is the sunspot than its surroundings?
Repeat your measurement of the Sun’s diameter several times and post your average value of the diameter in kilometers on the Blog. Include a comment about sig figs.
Comment on what you estimate is your measurement accuracy. How many significant figures are meaningful? (In other words, can you measure the diameter to an accuracy of one pixel? One tenth of a pixel? One hundredth of a pixel? None of these?)
How much fainter in DN units is the sunspot than its surroundings?
Repeat your measurement of the Sun’s diameter several times and post your average value of the diameter in kilometers on the Blog. Include a comment about sig figs.
Describe the general nature of the sun's surface around the location of this sunspot.
Module 2, Assignment 3
Describe your best simulations and your interpretations on the Blog. Also demonstrate the Stefan-Boltzmann Law by answering the following: when you double the temperature, by how much does its total energy increase?
Module 2, Assignment 4
At what temperature is the light in the B filter equal to the light in the R filter (i.e. the peak of the curves are the same height)? What is the lowest temperature at which U>B>V>R?
Which star is brighter in the B image? Which is brighter in the R image?
Send a screen shot of the 4 profiles to Chris Martin and post your analysis of which star is the hotter, A or B, on the blog.
Which star is brighter in the B image? Which is brighter in the R image?
Send a screen shot of the 4 profiles to Chris Martin and post your analysis of which star is the hotter, A or B, on the blog.
Module 3, Assignment 5
Post a list of the stars (identifying them by their HD, SAO or Feige numbers) your estimates of temperature (in degrees K), and the number of significant figures you believe are appropriate. Calculate the relative luminosity, compared to the coolest star in your sample, for each of the other 5 stars. To do this, select the coolest star in your sample and define its luminosity as 1, and scale the remaining stars to this one.
Module 4, Assignment 6
Send your pictures to Chris Martin and explain how you might use this activity with your students.
Module 5, Assignment 7
Send a screen shot of the spectrum of 41 Cygnus to Chris Martin. Explain what your temperature estimate is for this star.
Module 5, Assignment 8
Post your spectral class and temperature for three of the stars, identified by the HD number, as well as the spectral type, B, and V from SIMBAD. Include a screen shot of at least one spectrum (send to Chris Martin) with the lines you have identified.Which technique do you think is more accurate for determining spectral class- temperature as determined by Wien’s Law or as determined by spectral lines?
Module 6, Assignment 9
Comment on how the pencil appears to move with respect to a background object. Now, repeat this but with the pencil at a different distance from your face. How does the apparent shift of the pencil change?
Send a screen shot or copy of this plot to Chris. Comment on your plot. Do you see a relationship? Compare it with a published HR diagram: for example, see Wikipedia, Hertzsprung-Russell Diagram
Sort the data by B-V. (Remember, this is a measure of temperature.) How does B-V compare with the spectral types in the table? Make a table to express the relation. Make a third column for temperature. How does your table compare with the axes in the published HR diagram from Wikipedia?
Using the distance modulus equation, what distance do you derive?
Send a screen shot or copy of this plot to Chris. Comment on your plot. Do you see a relationship? Compare it with a published HR diagram: for example, see Wikipedia, Hertzsprung-Russell Diagram
Sort the data by B-V. (Remember, this is a measure of temperature.) How does B-V compare with the spectral types in the table? Make a table to express the relation. Make a third column for temperature. How does your table compare with the axes in the published HR diagram from Wikipedia?
Using the distance modulus equation, what distance do you derive?
Module 7
In this exercise, you will use imageJ with an astronomy plugin to create color (RGB) composite images. You will have to download the plugin and place files into your imagej program file. You will make color composite images using each image set. Send the images to martinbrockie@gmail.com. On the blog discuss how you constructed the images; adjusting, color combining and aligning.
Optional module 9
Send a screen shot of the HR diagram to Chris Martin and calculate the distance to the open cluster.
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