We present a study of the H \alpha line emission from a sample of 1482 optically-selected , morphologically-classified bright galaxies ( median redshift of 0.05 ) derived from the Sloan Digital Sky Survey .
The luminosity function is calculated for each morphological class and for the total sample .
The luminosity function fitted with the Schechter form gives a slope \alpha = -1.43 \pm 0.10 for the total sample and the H \alpha luminosity density is 10 ^ { 39.31 \pm 0.04 { +0.10 \atop - 0.07 } } h erg s ^ { -1 } Mpc ^ { -3 } , where the first error is statistical and the second is systematic .
This value is consistent with that derived by Gallego et al .
( 1995 ) , but this agreement is caused by a fortuitous cancellation of their neglect of stellar absorption that affects the estimate of extinction corrections and a significant sample incompleteness of emission line galaxies .
The fraction of H \alpha emitters monotonically increases from early ( a few % for ellipticals ) to late types ( 100 % for irregular galaxies ) , whereas strong emitters exist in all classes of morphological types .
We find that 83 % of the luminosity density comes from spiral galaxies , 5 % from irregular galaxies , and 9 % from early type galaxies ; a small number of morphologically disturbed galaxies contribute by 3 % .