Supernova Remnant Conclusions

Look again at the final plot.

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Astronomers determine the relative abundances of the elements in the supernova remnant by first identifying the energies of the lines with tables containing the emission line energies of the elements and of their ions. Astronomers also measure the fluxes in each of the observed lines. The flux measures how many photons are hitting each square centimeter of the satellite detector each second. For our supernova remnant, we have:

	Line energies	Flux (photons/cm2s-1)
Hydrogen-like O7+	0.65 keV	0.85
Helium-like O6+	0.55 keV	0.31
Hydrogen-like Ne9+	1.016 keV	0.02
Helium-like Ne8+	0.91 keV	0.04

(The line at 1.35 kev which we did not fit is He-like Magnesium.)

To estimate the relative abundances of the elements, one compares the fluxes of the lines. All the fluxes for the Neon can be summed and compared with the summed fluxes of the other lines (oxygen, for example). This comparison yields about 20x more oxygen than neon, which is what is seen in the sun and other stars. (Published values of element abundances are here.)

The hydrogen-like and helium-like ions that we see in this supernova remnant are very different from anything we would find on Earth. These ions are likely generated by very hot gas, greater than 10⁶ Kelvin. This heat energy must come from what is left over from the supernova. The estimates for the age of this supernova remnant come from observations of its expansion rate, and are in the range of 1000-2000 years. Thus it takes a supernova a very long time to cool off.

In this supernova remnant, we are seeing an incredible amount of oxygen, neon, and magnesium. These elements were made in the star that exploded and are now being spread into interstellar space in the Small Magellanic Cloud. This is the process by which the elements we are made of were originally produced.

Consider that this supernova remnant is very distant from Earth. It is not even in our galaxy, but in the Small Magellanic Cloud 200,000 light years away. For an object that far away to produce enough x-rays to make a few photons er square cm per second to Earth is extraordinary.