Tuesday, 15 March 2011

SXR208: Day 4

Day 4 - Spectroscopy

Today we hope to take spectrographic images of stars. It is quite amazing what you can do with a spectrum fo a star. You can work out what its made from, how big it is, which direction it is moving and all sorts of other things, which rather puts the final nail in the quote 
"On the subject of stars, all investigations which are not ultimately reducible to simple visual observations are ... necessarily denied to us. While we can conceive of the possibility of determining their shapes, their sizes, and their motions, we shall never be able by any means to study their chemical composition or their mineralogical structure ... Our knowledge concerning their gaseous envelopes is necessarily limited to their existence, size ... and refractive power, we shall not at all be able to determine their chemical composition or even their density... I regard any notion concerning the true mean temperature of the various stars as forever denied to us."
— Auguste Comte,

Waking up around 11:00, we headed toward the beach in search of food, and found a rather good paella, with lots of sea food in it. The sort that sticks out and looks at you.
Then after reading up on the evenings project, I met with some of my group. Some of the group wanted pre meeting planning to get things ready for the planning meeting. I arrived late, but joined in, and then it was soon time to board the bus. Another talk in the planetarium and then the planning session, where we again identified stars. Then off to get some food - very nice it was all week.

Then to the work in hand. First we had to calibrate the spectrometer. So this was done with a He-Ar lamp which produces a well defined spectrum. We took an image of this and then went off to the lab to make a calibration graph so we would be able to analyse the spectra we were to take.

Then the team I was in went off hunting around the sky for our targets. The first two were nice and easy to find, Arcturus and Regulus. We managed to get these stars onto the diffraction grating slit without too much trouble, but still made a couple of mistakes, but we had time as the clouds drifted by. We stopped for the midnight snack and lots of coffee.

Then it was onto a fainter object, BD+31 2750 - trips off the tongue! Finally Saturn just before the clouds rolled in and we had to stop for the night.

We managed to extract a few spectra, but some of our graphs seemed to be off by about 4nm. Something we couldn't explain despite redoing the calibration. We had a debrief with Andy which went pretty well, we decided we needed more data really. This was our first experience using real data, and we were all quite excited to have done something real.
The bus at 4:30am, and back home to bed at about 5:30 and make sure those do not disturb signs firmly attached.

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