Assignment 5: Planetary Nebulae

Due: Before 5 pm Tuesday, November 7, 2006. Please turn in hardcopy.

Planetary Nebulae form a short-lived phase in the evolution of stars with relatively small masses, less than about 8-10 times the mass of the Sun; the Sun will enter the Planetary Nebula stage in about 5.4 billion years. Go to www.google.com (or whatever your search engine of choice happens to be) and search for information on planetary nebulae. Search on "Planetary Nebula." Choose a likely site to visit and perform the following tasks. (What is the URL for your chosen site?)

1. Find another picture of the Helix nebula:

Print it and hand it in. Why does the outer portion of the appears reddish? What kind of spectrum do you expect the Helix Nebula to show? Upon which of Kirchhoff's Laws of Spectral Formation do you base your answer? The central star in the image is the core of the original star. It has a temperature of 100,000 K to 120,000 K! What kind of spectrum do you expect the central object to show? At what wavelength will its emission be the strongest? Eventually the central star will cool and become what is known as a white dwarf.

2. The ring shape of the Helix nebula does not tell us that the ejected gas came out in a ring. Explain why.