Spectrum of a
Supernova Remnant
There are three kinds of information that can be derived from the electromagnetic spectrum: images, spectra (singular is spectrum), and light curves. We will be working with analyses of spectra. A spectrum is a measure of the light emitted by an object (such as a Supernova Remnant or SNR) as a function of wavelength (or energy - the shorter a light wave's wavelength, the more energy it has). Spectra are useful tools because particular atoms, when excited, emit and/or absorb light at certain fixed wavelengths or energies. Scientists can use the spectral output from telescopes to determine the type of object that the telescope is viewing and how that object is changing. This is achieved by comparing the spectra from the telescope with a model of a known stellar object. The study of spectra is known as spectroscopy.
Follow this link for background on these analyses: http://imagine.gsfc.nasa.gov/docs/features/topics/snr_group/spectroscopy.html
HERA is
an analysis tool that can be used to study spectral images. The first
data set you will be analyzing is that of a Supernova remnant.
A supernovae remnant consists of gas left over after the explosion
of a massive star. The elements in this gas were made inside the star
and during the explosion of the star. The various gases in the remnant emit
light at specific energies; which can be visualized in a spectrum.
This leads to narrow features in the spectrum called emission
lines. By identifying what emission "lines" are present in a spectrum,
it is possible to tell what elements are present in the object
observed. So by looking at a supernova remnant's spectrum, it is
possible to tell what elements are in that remnant. All existing
elements heavier than Lithium were made in stars, and the likely path
out of the star was through a supernova. Essentially all elements in the entire galaxy has been processed through stars in this way. We will be working with a data set from supernova remnant E0102-72 that was observed with the Suzaku satellite. We will determine the elements present in this supernova remnant, and compare their relative abundances.
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