Variation of the Nebular Dust Attenuation Curve with the Properties of Local Star-forming Galaxies

We use a sample of $78,340$ star-forming galaxies at $z\simeq 0.04-0.1$ from the SDSS DR8 survey to calculate the average nebular dust attenuation curve and its variation with the physical properties of galaxies. Using the first four low-order Balmer emission lines (H$\alpha$, H$\beta$, H$\gamma$, H$\delta$) detected in the composite spectrum of all galaxies in the sample, we derive a nebular attenuation curve in the range of $0.41\mu$m to $0.66\mu$m that has a similar shape and normalization to that of the Galactic extinction curve (Milky Way curve), the SMC curve and the nebular curve derived in a previous study for a high redshift sample. We divide the galaxies into bins of stellar mass, gas-phase metallicity, and specific star-formation rate, and derive the nebular attenuation curve in each of these bins. This analysis indicates that there is very little variation in the shape of the nebular dust attenuation curve with the properties used to bin the galaxies. Although this suggests that the combined effect of the dust composition and geometry along the average nebular sightlines of those bins results in the nebular curves with identical shapes in the optical region, but it is not possible to draw any conclusion about the similarities in the dust properties (geometry and composition) alongside those sightlines.