PhD introductory 3-month project
Measurements from the spectra stars in globular cluster NGC 288 have shown (Roh et al. 2011, ApJ, 733, L45) that in a plot of brightness in the y waveband (the Stromgren equivalent of the visual V band) against the spectral index termed the hk index (formed from the emission measured in a narrow-band filter that covers the Ca I H and K lines), the red giant branch is split into two distict branches. However, in a colour-magnitude plot of y magnitude against the b-y colour (a measure of the relative difference in emission within these two wavebands), only a single branch is seen. Roh et al. go on to claim that the split is due to two distinct populations whose overall abundances differ by ~0.16 dex. Most other workers in the field think this result is due to two populations whose CN-band strengths differ while the heavy element abundances do not vary.
We have obtained, for another project, AAOmega spectra of red giants in this cluster at the Ca II triplet (a chemical abundance indicator), at blue wavelengths (CN, CH band strengths, also Ca II K line) and at 5900Å (including the Na D lines, which should correlate with CN-band strength). This short project will involve reducing and measuring the properties of these spectra.
The expectation is that the CaII triplet and CaII K-lines won't show any evidence for abundance variations but CN/CH/Na will show a bimodal population as seen in many other clusters. However, we can not be sure. The reduction and analysis will be carried out over 3-4 months and the results will easily form a paper. Some level of computing knowledge will be helpful for this project, but not necessary (though learning the basics may add to the total time required to complete the work).