We present a detailed study of the extremely isolated Sdm galaxy UGC 4722 ( M _ { B } = -17.4 ) located in the nearby Lynx-Cancer void .
UGC 4722 is a member of the catalogue of isolated galaxies , and has also been identified as one of the most isolated galaxies in the Local Supercluster .
Optical images of the galaxy however show that it has a peculiar morphology with an elongated \sim 14 kpc-long plume .
New observations with the Russian 6-m telescope ( BTA ) and the Giant Metrewave Radio Telescope ( GMRT ) of the ionised and neutral gas in UGC 4722 reveal the second component responsible for the disturbed morphology of the system .
This is a small , almost completely destroyed , very gas-rich dwarf ( M _ { B } = -15.2 , M ( H i ) / L _ { B } \sim 4.3 ) We estimate the oxygen abundance for both galaxies to be 12 + \log ( \textrm { O / H } ) \sim 7.5 - 7.6 which is 2–3 times lower than what is expected from the luminosity-metallicity relation for similar galaxies in denser environments .
The ugr colours of the plume derived from Sloan Digital Sky Survey ( SDSS ) images are consistent with a simple stellar population with a post starburst age of 0.45–0.5 Gyr .
This system hence appears to be the first known case of a minor merger with a prominent tidal feature consisting of a young stellar population .