ar X iv : 0 70 7 . 23 77 v 1 [ as tr o - ph ] 1 6 Ju l 2 00 7 The bright and the dark side of Malin 1

h −1 [75] (scale length 53 kpc). This corresponds to the H I extent. There is also a prominent bulge-like component. According to Pickering et al. [3] the rotation curve has the slowly rising shape typical of the less luminous, “dark matter dominated” LSB galaxies. This slow rise of the rotation curve in the presence of a luminous central component is in marked contrast with the rule that there is a close correlation between the distribution of light and the shape of the rotation curve [6]. However, Pickering et al. [3] do point out that their rotation curve is very uncertain because of the low resolution of the observations, the low signal/noise ratio and the strong warping. This has induced us to carry out a re-analysis of the H I data with special attention for the beam-smearing effects and to make a new comparison with the luminosity profile. The results of our analysis agree with those of a recent HST optical study of the bright central component [1]: Malin 1 is a normal, early-type galaxy surrounded by a huge, low-surface-brightness outer disk.