Empirical relationship between calcium triplet equivalent widths and [Fe/H] using Gaia photometry

I present a new empirical relationship for red giant branch stars between the overall metallicity of the star and the sum of equivalent widths of the near-infrared calcium triplet (CaT) spectral lines. This method takes advantage of the all-sky photometry and astrometry of the Gaia mission, and the archival spectra from 2050 red giant branch stars from 18 globular clusters (-0.69>[Fe/H]>-2.44) acquired with the Anglo-Australian Telescope's AAOmega spectrograph.

.tar.gz

Raw and reduced spectra for 18 globular clusters (NGC104, NGC6752, NGC6809, NGC288, NGC7099, NGC362, NGC6218, NGC4590, IC4499, NGC1904, ESO452-SC06, ESO280-SC12, NGC1851, NGC6624, NGC2298, Pal 5, NGC5024, Terzan 8, NGC5053)

Lists of likely members

Measured equivalent widths and radial velocities

code.tar.gz

running.py – calculates the equivalent widths and radial velocities of the stars from the spectra

cat_new_params.py – calculates the best fitting empirical relationship

paper.tar.gz

The LaTeX source for the submitted RNAAS paper.