1. Determining Abundances
Classical curve of growth analysis
Fine analysis or detailed analysis
computes a curve of growth for each individual line using a model atmosphere
Differential analysis
Derive abundances from one star only relative to another star
Usually differential to the Sun
gf values not needed
Spectrum synthesis
Uses model atmosphere, line data to compute the spectrum

2. Jargon [m/H] = log N(m)/N(H)star – log N(m)/N(H)Sun
[Fe/H] = -1.0 is the same as 1/10 solar
[Fe/H] = -2.0 is the same as 1/100 solar
[m/Fe] = log N(m)/N(Fe)star – log N(m)/N(Fe)Sun
[Ca/Fe] = +0.3 means twice the number of Ca atoms per Fe atom

3. Solar Abundances from Grevesse and Sauval

4. Basic Methodology for “Solar-Type” Stars
Determine initial stellar parameters
Composition
Effective temperature
Surface gravity
Microturbulence
Derive an abundance from each line measured using fine analysis
Determine the dependence of the derived abundances on
Excitation potential – adjust temperature
Line strength – adjust microturbulence
Ionization state – adjust surface gravity

5. Projects!
Derive the composition of Arcturus from high resolution infrared spectra. Compare results to optical determinations.
Adopt the published model atmosphere parameters
Use the Hinkle et al. atlas to measure equivalent widths
Derive gf values from the solar spectrum

6. Project II
Derive the composition of one (or two or three) giants in the globular cluster M3 from high resolution IR Keck/NIRSPEC spectra
Differential analysis relative to Arcturus
Use published model atmosphere parameters

7. Project III
Derive model atmosphere parameters from measured equivalent widths for the G8 III giant Epsilon Virginis
Use laboratory gf’s

8. Project IV
Derive spectroscopic atmospheric parameters for the Sun from measured equivalent widths and published laboratory gf values
Determine the solar iron abundance from Fe I and Fe II lines

9. Project V
Determine atmospheric parameters for a metal-poor giant or subgiant from measured equivalent widths and laboratory gf-values