TiO band strengths in metal-rich globular clusters. III - Model atmosphere calibration

We present model atmosphere calculations of the run of TiO band strength with color temperature in globular cluster giants. This permits a more reliable calibration to be constructed of near-infrared narrow-band photometry in globulars. Published observations suggest either a substantially higher ratio of titanium to iron in the halo than in the Sun or an unrecognized problem in the recent recalibration of the globular cluster abundance scale.