While major mergers and their tidal debris are well studied , they are less common than minor mergers ( mass ratios \lesssim 0.3 ) .
The peculiar spiral NGC 2782 is the result of a merger between two disk galaxies with a mass ratio of \sim 4 : 1 occurring \sim 200 Myr ago .
This merger produced a molecular and H i rich , optically bright Eastern tail and an H i -rich , optically faint Western tail .
Non-detection of CO in the Western Tail by Braine et al .
( 4 ) suggested that star formation had not yet begun to occur in that tidal tail .
However , deep H \alpha narrowband images show evidence of recent star formation in the Western tail .
Across the entire Western tail , we find the global star formation rate per unit area ( \Sigma _ { SFR } ) several orders of magnitude less than expected from the total gas density .
Together with extended FUV+NUV emission from Galaxy Evolution Explorer along the tail , this indicates a low global star formation efficiency in the tidal tail producing lower mass star clusters .
The H ii region we observed has a local ( few-kpc scale ) \Sigma _ { SFR } from H \alpha that is less than that expected from the total gas density , which is consistent with other observations of tidal debris .
The star formation efficiency of this H ii region inferred from the total gas density is low , but normal when inferred from the molecular gas density .
These results suggest the presence of a very small , locally dense region in the Western tail of NGC 2782 or of a low metallicity and/or low pressure star forming region .