SIMBAD references

Cepheids have been observed in NGC 5236 (M83) using the Antu (Unit Telescope 1) 8.2 m telescope of the ESO Very Large Telescope with the Focal Reducer/Low Dispersion Spectrograph 1. Repeated imaging observations have been made between 2000 January and 2001 July. Images were obtained in 34 epochs in the V band and in six epochs in the I band. The photometry was made with the ROMAFOT reduction package and checked independently with DoPHOT and a modified version of HSTPHOT. Twelve Cepheid candidates have periods ranging between 12 and 55 days. The dereddened distance modulus is adopted to be (m-M)⁰=28.25±0.15, which corresponds to a distance of 4.5±0.3 Mpc. The Cepheid distance of NGC 5253 has been rediscussed and strengthened by its SN 1972E. The mean distance of (m-M)⁰=28.01±0.15 (based on SN 1972E) shows the galaxy to be a close neighbor of M83, suggesting that the two galaxies may have interacted in the past and thus possibly explaining the amorphous morphology of NGC 5253. The distance difference between M83 and NGC 5253 is only 0.5±0.4 Mpc. The projected distance is only ∼ 0.15 Mpc. M83 is the principal member of the nearby M83 group containing also, besides NGC 5253, several dwarf members, for five of which tip of the red giant branch distances are available. The adopted group distance of (m-M)⁰=28.28±0.10 (4.5±0.2 Mpc), together with its mean recession velocity of v_LG=249±42 km.s^–1, shows again the extreme quietness of the local (1-10 Mpc) expansion field. M83 fits onto the local mean Hubble flow line of the velocity-distance relation (with H₀∼60) with no significant deviation, supporting the earlier conclusion that the local velocity expansion field is remarkably cold on a scale of 10 Mpc, contrary to the predictions of the simplest cold dark matter model for large-scale structure. The role of a cosmological constant has been invoked as a possible solution in providing a nearly uniform force field everywhere in the presence of a lumpy galaxy distribution.