Quick Navigation

Northern Illinois University

Department of Physics

Physics 162H Honors Project: Stellar Life Cycle

The life of a star in our universe is cyclic. A star is born from dense concentrations of gas in a molecular cloud. Small particulate matter forms a center, and slowly, more and more gas accretes in and begins to form the proto-star. Eventually, the star achieves a critical mass which causes the core to begin performing HH fusion cycles frequently enough for the star to shine forth, beginning its life.

Stars progress through various stages in their life cycle. They start from the meager hydrogen burner and proceed in their lives to burn heavier elements, up until either the star runs out of viable fuel mass or a core of solid iron is achieved. The fate of a star depends on its original mass. Less massive stars simply sputter out, and their remaining gaseous shells are ejected free. More massive stars undergo spectacular deaths in supernova explosions.

Either way, the end product is typically a cloud of material which was ejected from the dying star, of varying density. Parts of this cloud can accrete and form a next generation star and begin the process anew. As a rule, second generation stars are less massive than their parents, barring unusual circumstances. They also contain a higher abundance of heavier elements.

This project will require a large number of casual non-intensive observations. The endeavor is to locate evidence of this life cycle of the stars in the night skies. It will include the following: an observation of a nebula as a birthplace and death marker of the stars, an observation of a star in the main sequence of its life, and an observation of newly formed stars, particularly stars in a star cluster. An observation of different types of stars, red giants, blue giants, etc., may be helpful to this project.

Procedure

  1. Devise a plan of attack. Consult with the observatory manager and choose the objects you wish to try to view through the telescope. Messier objects are the most likely to be found, so it is strongly recommended that you stick to the Messier Catalog. It is also recommended that you choose objects visible in the Northern hemisphere. Find coordinates for your desired objects. For this project, there are several recommended objects:
    - The Pleiades (7 Sisters) Star Cluster.
    - The stars Antarres, Vega, or Sirius.
    - The Crab Nebula, M-1, which has historical documentation of its death. This is found in Taurus.
    - The Triumvarate. Three new stars formed from the Great Orion nebula.
  2. Locate each object in the telescope at Davis Hall.
  3. With the manager's assistance attach either a camera or the CCD to the scope. An option for a very faint nebula is to observe it visually and attempt to sketch a picture. Most of the nebulae visible from DeKalb will probably require CCD shots due to the light pollution and photographic difficulty. The stars and star clusters should be readily visible.
  4. Capture at least one image, or more if you choose. Try several different images in different scopes and powers of magnification.
  5. With use of photography, or with the CCD images, the pictures may be enlarged so that they may be more visible. For a nebula, the important part is to be able to distinguish the nebula from the background. For the stars, it is enough to observe thier color differences and brightness, and you probably won't need a picture, though they could be a nice addition to the report.

Data Intepretation

For the most part, this should be self explanatory. You will have to take each of the separate observations and say why they might be observed, how they fit into the stellar life cycle, and any other implications each object might have. A discussion of supernovae and star formation will be integral to this project, as will a number of trips to the Observatory, unless you are lucky enough to capture what you require in one night.