We present a sample of 1716 galaxies with companions within ∆v< 500 km s −1, rp < 80 h −1 70 kpc and stellar mass ratio 0.1 < M1/M2 < 10 from the Sloan Digital Sky Survey (SDSS) Data Release 4 (DR4). The galaxy pairs are selected from the Main Galaxy Sample using stringent and well-understood criteria for redshift, spectral quality, available stellar masses and metallicities. In agreement with previous studies, we find an enhancement in the star formation rate (SFR) of galaxy pairs at projected separations < 30–40 h −1 70 kpc. In addition, we find that this enhancement is highest (and extends to the greatest separations) for galaxies of approximately equal mass, the so-called ‘major ’ pairs. However, SFR enhancement can still be detected for a sample of galaxy pairs whose masses are within a factor of 10 of each other. Based on these results, we define a sample of close pairs (∆v< 500 km s−1, rp <30 h −
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