New distances of unresolved dwarf elliptical galaxies in the vicinity of the Local Group

Abstract

Abstract. We present Surface Brightness Fluctuation distances of nine early-type dwarf galaxies and the S0 galaxy NGC 4150 in the Local Volume based on deep B-and R-band CCD images obtained with the 2.56 m Nordic Optical Telescope. Typically, six stellar fields at various galactocentric distances have been chosen for each galaxy as appropriately free of foreground stars and other contaminants, and Fourier analysed to determine the distances, which are found to lie in the range of 3 to 16 Mpc. The SBF method is thus demonstrated to efficiently measure distances from the ground with mid-aperture telescopes for galaxies for which only the tip of the red giant branch method in combination with the Hubble Space Telescope has been available until now. We obtained the following distance moduli: 28.11 ± 0.15 mag (or 4.2 ± 0.3 Mpc) for UGC 1703, 27.61 ± 0.17 mag (or 3.3 ± 0.3 Mpc) for KDG 61, 29.00 ± 0.27 mag (or 6.3 ± 0.8 Mpc) for UGCA 200, 27.74 ± 0.18 mag (or 3.5 ± 0.3 Mpc) for UGC 5442, 30.22 ± 0.17 mag (or 11.1 ± 0.9 Mpc) for UGC 5944, 30.79 ± 0.11 mag (or 14.4 ± 0.7 Mpc) for NGC 4150, 31.02 ± 0.25 mag (or 16.0 ± 1.9 Mpc) for BTS 128, 29.27 ± 0.16 mag (or 7.1 ± 0.6 Mpc) for UGC 7639, 30.19 ± 0.23 mag (or 10.9 ± 1.2 Mpc) for UGC 8799 with an alternative distance of 30.61 ± 0.26 mag (or 13.2 ± 1.7 Mpc), and 29.60 ± 0.20 mag (or 8.3 ± 0.8 Mpc) for UGC 8882.

New low surface brightness dwarf galaxies in the Centaurus group

“…Another means to measure distances of galaxies is the surface brightness fluctuation method (SBF; Tonry & Schneider 1988). This method was successfully tested for earlytype dwarfs by Jerjen et al (2000b) and used to measure distances to five dE galaxies in the Centaurus group and many more in the Local Volume (Jerjen et al 2001;Rekola et al 2005). The minimum exposure time required for the SBF method to work can be calculate using equation (1) in Dunn & Jerjen (2006).…”

SAPAC: a SBF analysis pipeline for the astronomical community

“…Tonry et al 1989Tonry et al , 1994 but was found to work equally well with dwarf elliptical (dE) galaxies (e.g. Jerjen et al 1998, 2000, 2001, 2004, and Rekola et al 2005. As dE galaxies are by far the most numerous galaxy type at the current cosmological epoch, the SBF method in combination with wide-field CCD imaging offers the opportunity for the first time to spatially locate dEs in vast numbers and thereby to map in 3D the densest environments of the local Universe (for first results see contributions by Côté et al, Jerjen, Jordan et al, and Rekola et al in this volume).…”

“…A SBF distance can be determined when the S/N is approximately 0.5, (see Fig. 8 in Rekola et al 2005), but that depends largely on the image quality i.e. seeing.…”

Star Formation History of KDG 61 and KDG 64 From Spectroscopy and Colour-Magnitude Diagrams

“…The corresponding distances are 3.6 Mpc and 3.7 Mpc, respectively. Rekola et al (2005) has obtained distance moduli of 27.61 ± 0.17 (D = 3.3 Mpc) for KDG 61 and 27.74 ± 0.18 (3.5 Mpc) for KDG 64 using surface brightness fluctuation (SBF) method based on Band R-band images obtained with the Nordic Optical Telescope. Both measurements give consistent distances for our galaxies although the SBF measurements seem to give a little shorter scale.…”