| Résumé | The star formation rates (SFRs) and metallicities of a sample of 294 galaxies with visually classified, strong, large-scale bars are compared to a control sample of unbarred disc galaxies selected from the Sloan Digital Sky Survey Data Release 4. The fibre (inner few kpc) metallicities of barred galaxies are uniformly higher (at a given mass) than the unbarred sample by similar to 0.06 dex. However, the fibre SFRs of the visually classified barred galaxies are higher by about 60 per cent only in the galaxies with total stellar mass M★ > 10¹° M⊙. The metal enhancement at M★ < 10¹° M⊙ without an accompanying increase in the SFR may be due to a short-lived phase of early bar-triggered star formation in the past, compared to on-going SFR enhancements in higher mass barred galaxies. There is no correlation between bar length or bar axial ratio with the enhancement of the SFR. In order to assess the relative importance of star formation triggered by bars and galaxy-galaxy interactions, SFRs are also determined for a sample of close galaxy pairs. Both mechanisms appear to be similarly effective at triggering central star formation for galaxies with M★ > 10¹° M⊙. However, due to the much lower fraction of pairs than bars, bars account for similar to 3.5 times more triggered central star formation than interactions. |
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