Quantitative Analysis of the Oscillation Spectrum of η Bootis

We analyze the recent ground-based p-mode oscillation observations of η Boo by Kjeldsen and his collaborators using a large and dense grid of stellar model oscillation spectra parameterized by mass, age, and metallicity. The differences between the model and observed oscillation spectra are quantified by a χ2 formulation. Based on the seismic data alone we determine two possible solutions for η Boo's mass, age, and metallicity. One solution exhibits mode bumping and is within 1 σ of η Boo's observed luminosity, effective temperature, and metallicity, and the other solution does not exhibit mode bumping and is within 2 σ of η Boo's observed luminosity, effective temperature, and metallicity. We show how mode bumping (also associated with the terms "mixed modes" and "avoided crossings") can be used to fine-tune the age determination. We also show that the nonadiabatic model frequencies are in better agreement with the observed frequencies than the adiabatic frequencies.