The Stellar Halo of the Spiral Galaxy NGC 1560

Abstract

We report on the detection of a stellar halo around NGC 1560, a 10<SUP>9</SUP> M <SUB>☉</SUB> spiral galaxy member of the Maffei group. We obtained deep images in the r- and i-bands using the 10.4 m Gran Telescopio Canarias in a field centered at ∼3.7 arcmin (projected distance of 3.5 kpc) from the center of this galaxy. The luminosity function and the color-magnitude diagram show a clear excess of stars with respect to the expected foreground level at magnitudes fainter than the red giant branch tip at the distance of NGC 1560. The colors of the halo stars imply a metallicity of Z ∼ Z <SUB>☉</SUB>/50, while their counts correspond to a stellar mass of ∼10<SUP>7</SUP> M <SUB>☉</SUB> in the sampled region. Assuming a power-law profile for the surface mass density of the halo, our data suggest a total stellar mass of 10<SUP>8</SUP> M <SUB>☉</SUB> for the halo of NGC 1560.