Unit Five: Investigating Stars
4. Supernova Remnants and Planetary Nebulae
Stars with one solar mass or less end their lives by shedding much of their mass into space as planetary nebulae (PNs), while more massive stars expel their mass as clouds of gas and dust called supernovae remnants (SNRs). PNs and SNRs are among the most beautiful and complex objects seen in the sky, and many of the brighter ones are popular targets for amateur astronomers. While striking color images tell us about the structure of these expanding nebulae, other questions arise: what are those knots of gases made of? How hot are they? How fast are they traveling? PNs and SNRs are formed in events of greatly differing energies and violence. Are their differences between the PNs and SNRs that are the result of radically different processes producing their demise? In this Doing Science, you will examine multi-spectral images and spectra of PNs and SNRs to investigate systematic differences between them and what those differences tell us about these two forms of stellar death.
Visit the following sites for images and data abut PNs and SNRs:
Visible Images: Hubble Site Gallery Picture album http://hubblesite.org/gallery/album/
X-Ray Images and spectra: High Energy Astrophysics Science Archive Research Center http://heasarc.gsfc.nasa.gov/
[Note, the conversion between energy, E, in kilo-electron volts (kev) and wavelength, λ, in Angstroms is: λ = 12.40/E(kev)]
Gallery of Planetary Nebulae Spectra: http://www.williams.edu/Astronomy/research/PN/nebulae/
More visible images and general information: SEDS SNR page http://www.seds.org/messier/snr.html
Select 3 representative PNs and SNRs. Collect visible and X-ray images and spectra of each. For each object, find or estimate the temperature, composition, expansion velocity, and mass of the nebula. Some of this information you can derive directly from the images and spectra; some of it you will need to locate by further library or Internet search (keywords: planetary nebula, supernova remnant, spectra).
Make a summary poster or PowerPoint containing images, spectra, and a table of information about each object. Examine your data to determine typical composition, temperature, expansion velocity, masses, and description of the structure of PNs and SNRs. Write a short summary of the differences between the two types of objects, and what those differences tell you about the nature of PN formation and supernova explosions.