| The 15R-North galaxy survey is a sample of 3149 optical spectra (3650--7400A), with median redshift 0.05. The sample is 90% complete to RC = 15.4. I use spectral features including Halpha 6563A to classify the galaxies spectroscopically, and measure local density and synthetic colors. The main results are (1) ≥22% of the galaxies are star-forming, ≥16% have AGN-like emission, and an additional ≥14% have emission that cannot be classified with the available data; (2) the unclassified 14% may include a "hybrid" population of galaxies with both star-formation and AGN activity; (3) when estimating star-formation rates from the [OII] 3727A line (in cases where Halpha is unavailable), a luminosity correction gives a better estimate than the [OII] line alone; (4) spectral type is correlated with local density much as galaxy morphology correlates with density; and (5) the star-formation rate (estimated from Halpha) is only weakly correlated with local density. |
