Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.
What is the mystery star?
This project must be done by individuals.
Joe Cosmos
uses his telescope to take spectra
of objects in the sky:
stars, galaxies, nebulae -- he's seen them all.
One night, he acquires the spectrum
of an faint object.
What could it be?
- Download the spectrum.
The data file has two columns: the first one is wavelength,
(in Angstroms), and the second is flux (energy per second
per square meter per unit wavelength).
Your job: identify the mystery object.
You might follow these steps:
- Download the data file
- Make a plot of flux versus wavelength. Print it out,
and include it in your report.
- Look for absorption lines. If this is the spectrum of
a star, there should be "dark" (absorption) lines
due to cool gas in the star's upper atmosphere.
Mark some of the strongest lines you can find.
Measure their wavelengths by making zooming in
on the spectrum (replot it on your screen or on paper)
so that you focus on a stretch of 500 to 1000 Angstroms;
that will let you measure the bottom of each line accurately.
- In ordinary stars, the lines of hydrogen often appear strong
(there's a lot of hydrogen in stellar atmospheres).
Can you find lines due to hydrogen?
Again, zoom in on the graph to measure their wavelengths
accurately.
- Look at the overall shape of the spectrum. Estimate
the temperature of the mystery star.
- Classify the spectrum of this star. Provide
reasons for your classification.
Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.