The Araucaria Project. Infrared TRGB distances to the Carina and Fornax dwarf spheroidal galaxies

TL;DR

This paper uses near-infrared TRGB measurements to accurately determine the distances to the Carina and Fornax dwarf spheroidal galaxies, confirming consistency with other distance indicators.

Contribution

It provides new near-infrared TRGB distance measurements for Carina and Fornax, with detailed error analysis and comparison to optical methods.

Findings

Distances agree with optical TRGB, HB, RR Lyrae, and red clump measurements.

Statistical errors are around 0.03-0.04 mag, systematic uncertainties about 0.12-0.14 mag.

Near-infrared TRGB is a reliable distance indicator for dwarf galaxies.

Abstract

We present distance determinations for two Local Group dwarf spheroidal galaxies, Carina and Fornax, based on the near-infrared magnitudes of the tip of the red giant branch (TRGB). For Carina we derive true distance moduli of 20.09 and 20.13 mag in the J and K bands, respectively, while for Fornax the same distance modulus of 20.84 mag was derived in both filters. The statistical errors of these determinations are of order 0.03-0.04 mag, whereas the systematic uncertainties on the distances are 0.12 mag in the J band and 0.14 mag in the K band. The distances obtained from the near-infrared TRGB method in this paper agree very well with those obtained for these two galaxies from optical calibrations of the TRGB method, their horizontal branches, RR Lyrae variables, and the near-infrared magnitudes of their red clumps.