Transformations between 2MASS, SDSS and BVI photometric systems for late-type giants

TL;DR

This paper develops color transformations between 2MASS, SDSS, and Johnson-Cousins photometric systems specifically for late-type giants, enabling accurate magnitude and distance estimations.

Contribution

It provides new two-color dependent transformations for late-type giants, incorporating metallicity effects, for the first time in this context.

Findings

Transformations are valid for high-quality, dereddened data.

Transformations include metallicity dependence.

Results enable improved distance and space density calculations.

Abstract

We present colour transformations from Two Micron All Sky Survey (2MASS) photometric system to Johnson-Cousins system and to Sloan Digital Sky Survey (SDSS) system for late-type giants and vice versa. The giant star sample was formed using surface gravity constraints ($2 < \log g \leq 3$) to Cayrel de Strobel et al.\rq s (2001) spectroscopic catalogue. 2MASS, SDSS and Johnson-Cousins photometric data was taken from Cutri et al. (2003), Ofek (2008) and van Leeuwen (2007), respectively. The final sample was refined applying the following steps: (1) the data were dereddened, (2) the sample stars selected are of the highest photometric quality. We give two--colour dependent transformations as a function of metallicity as well as independent of metallicity. The transformations provide absolute magnitudes and distance determinations which can be used in space density evaluations at relatively short distances where some or all of the SDSS magnitudes of late-type giants are saturated.