We present the Fabry–Perot observations obtained for a new set of 108 galaxies in the frame of the Gassendi Hα survey of SPirals (GHASP). The GHASP survey consists of 3D Hα data cubes for 203 spiral and irregular galaxies, covering a large range in morphological types and absolute magnitudes, for kinematics analysis. The new set of data presented here completes the survey. The GHASP sample is by now the largest sample of Fabry–Perot data ever published. The analysis of the whole GHASP sample will be done in forthcoming papers. Using adaptive binning techniques based on Voronoi tessellations, we have derived Hα data cubes from which are computed Hα maps, radial velocity fields as well as residual velocity fields, position–velocity diagrams, rotation curves and the kinematical parameters for almost all galaxies. Original improvements in the determination of the kinematical parameters, rotation curves and their uncertainties have been implemented in the reduction procedure. This new method is based on the whole 2D velocity field and on the power spectrum of the residual velocity field rather than the classical method using successive crowns in the velocity field. Among the results, we point out that morphological position angles have systematically higher uncertainties than kinematical ones, especially for galaxies with low inclination. The morphological inclination of galaxies having no robust determination of their morphological position angle cannot be constrained correctly. Galaxies with high inclination show a better agreement between their kinematical inclination and their morphological inclination computed assuming a thin disc. The consistency of the velocity amplitude of our rotation curves has been checked using the Tully–Fisher relationship. Our data are in good agreement with previous determinations found in the literature. Nevertheless, galaxies with low inclination have statistically higher velocities than expected and fast rotators are less luminous than expected.
The Gassendi HAlpha survey of SPirals survey (GHASP) consists of 3D Hα data cubes for 203 spiral and irregular galaxies, covering a large range in morphological types and absolute magnitudes, for kinematics analysis. It is the largest sample of Fabry–Perot data published up to now. In order to provide an homogenous sample, reduced and analysed using the same procedure, we present in this paper the new reduction and analysis for a set of 97 galaxies already published in previous papers but now using the new data reduction procedure adopted for the whole sample. The GHASP survey is now achieved and the whole sample is reduced using the adaptive binning techniques based on Voronoi tessellations. We have derived Hα data cubes from which are computed Hα maps, radial velocity fields as well as residual velocity fields, position–velocity diagrams, rotation curves and kinematical parameters for almost all galaxies. The rotation curves, the kinematical parameters and their uncertainties are computed homogeneously using the new method based on the power spectrum of the residual velocity field. This paper provides the kinematical parameters for the whole sample. For the first time, the integrated Hα profiles have been computed and are presented for the whole sample. The total Hα fluxes deduced from these profiles have been used in order to provide a flux calibration for the 203 GHASP galaxies. This paper confirms the conclusions already drawn from half the sample concerning (i) the increased accuracy of position angles measurements using kinematical data, (ii) the difficulty to have robust determinations of both morphological and kinematical inclinations in particular for low‐inclination galaxies and (iii) the very good agreement between the Tully–Fisher relationship derived from our data and previous determinations found in the literature.
We present GALEX UVobservations of a sample of low surface brightness ( LSB) galaxies for which H i data are available, allowing us to estimate their star formation efficiency. We find that the UV light extends to larger radii than the optical light (some galaxies, but not all, look similar to the recently discovered XUV-disk galaxies). Using a standard calibration to convert the UV light into star formation rates, we obtain lower star formation efficiencies in LSB galaxies than in high surface brightness galaxies by about one order of magnitude. We show, however, that standard calibrations may not apply to these galaxies, as the FUVÀNUV color obtained from the two GALEX bands (FUV and NUV; k eA ¼ 1516 and 2267 8, respectively) is redder than expected for star-forming galaxies. This color can be interpreted as a result of internal extinction, modified initial mass function, or star formation histories characterized by bursts followed by quiescent phases. Our analysis favors this latter hypothesis.
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