Stellar Spectra
Description
In this lab, students see if they can use Wien's law to demonstrate the match between stellar temperatures (from their color) and their spectra.
Procedure
We know that stars glow because they are hot, but how well do their spectra match the expected blackbody (or thermal emission) spectrum? You will use real stellar spectra from SDSS and Wien's law to answer this question. Although it's fine to work with someone on this assignment, each person in the class should find their own objects and create their own page.
Important Note: You won't be able to use the link to Navigate in the Voyages page for this lab, instead use:
The Voyages page for this lab no longer exists, so I'm using a copy of it from the Internet Archive's Wayback Machine. I'm glad we can still see it, but links to the SDSS tools don't go to the real tool, but just to a snapshot of what it used to look like.
Navigate to Voyages: Stars as Blackbodies. Remember that the SDSS Navigate tool and other non-text content won't work.
Gather data, except:
I didn't find it necessary to use separate notebooks for this lab, so I didn't make an account.
Your starting place can be the RA and Dec from your special place in the SDSS, or you can choose a new spot.
Collect around five blue stars with spectra and five red stars with spectra (if you're not sure if your stars have spectra go back and remember to check the "Objects with spectra" box under "Drawing options").
Some plots in the SDSS have very few red stars with spectra. If there aren't any red stars with spectra where you're looking, move to a new location that's at least five degrees away from where you were and try again.
Clean your data. The Voyages website doesn't mention this, but some of the "stars" you collected might be remote galaxies with active super-massive black holes(!). These particular active galaxies look a lot like stars, so they are called Quasi-Stellar Objects or QSOs. The "STAR" classification you used earlier is based on imagery, but after the spectra is taken the object is reclassified, and some stars turn out to be QSOs. You'll need to clean these out of your data.
For each object in your notebook, click on "Explore".
Look for the "class" entry (under "Optical Spectra", and also on the spectrum itself).
If it says "QSO" it's not a star. Delete it.
If it says "STAR", you can save the thumbnail image now.
After you have collected your data, create a page that has:
Two to three stars that demonstrate typical red star spectra. You must show both the image of the star and its spectrum.
Two to three stars that demonstrate typical blue star spectra. You must show both the image of the star and its spectrum.
A short paragraph (at least three sentences) that answers the question, "Can you use Wien's law to tell hot stars from cool stars?" Be sure to refer to the spectral features you see that are relevant to thermal radiation.
You're welcome to use any tool that can arrange text on a page, but please submit something Canvas can open (Microsoft Word, Powerpoint, or a pdf).
Suggested Rubric
