I have data!

TL:DR version: I have data. I'm excited. YAY! :)

Long version: It's only mid-July and I have preliminary results for my summer research project! "Only mid July"?? I can't believe I'm writing this - summer is flying past, as only hot and happy summers can do. But the point here isn't to mourn the passing of summer, but to celebrate some data!

Basically, at the end of a long learning curve, I've figured out the rough chemical composition of 3 stars in the Carina Dwarf galaxy. We had estimates that they would be very "metal-poor" (which is mostly what it sounds like - minimal heavy elements in the atmosphere, so therefore mostly made up of hydrogen and helium, the lightest elements). For astro geeks that might happen by, iron abundances are 4.94, 4.65 and 4.33 (metallicities of -2.58, -2.87 and -3.19)

2 months of work to yield 3 numbers?? What does it MEAN?
The "abundance" is a way of measuring the concentration of a particular element in a star. It's kind of like a measure of the number of atoms you would count in a 1cm tube that goes all the way from the atmosphere of the star to the star's surface. Put this on a logarithmic scale, compare it to our sun, and you get a metallicity. Logarithms work on powers of 10, so 1 2 3 is really 10 100 1000. it's just like the Richter scale - a magnitude 7.0 earthquake is 10 times more powerful than a 6.0. So a metallicity of -3.19 means heavy elements make up only 0.0646% as much of the star's atmosphere as they do in our sun.

Metal-poor stars are interesting because they formed in very primal environments. Since heavy elements are made in the supernovae explosions of dying stars, a metal-rich star must have formed from the debris of many past generations of stars. Metal-poor stars have all either formed earlier (so that their environment wasn't enriched with heavy elements from past generations) or in isolation. The oldest stars in the galaxy must be metal-poor, since there wasn't many heavy elements in the early universe

So, I've confirmed the estimated metallicity of the 3 most metal-poor stars we could find. This is neat because the tricks astronomers use for estimating these things didn't necessarily apply to stars that are this metal poor, so I've verified that the estimation is better than originally thought :)

Sadly, the data isn't strong enough to tell many details of the star's makeup. How much barium, sodium and nickel is there in the atmosphere?? we don't know - and we need this to find out what type of supernovae had happened in the neighbourhood before these stars formed, which tells us whether there were large or small stars, hot or cool, etc etc.

If anyone actually read this far, GET A LIFE! Or, check out wikipedia pages on metallicity ( http://en.wikipedia.org/wiki/Metallicity ) or abundances (http://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements)

Or, look at a dry graph :)