Two long H i tails in the outskirts of Abell 1367

Accepted. Received; in original form We present VLA D–array H i observations of the RSCG42 and FGC1287 galaxy groups, in the outskirts of the Abell 1367 cluster. These groups are projected ∼ 1.8 and 2.7 Mpc west from the cluster centre. The Arecibo Galaxy Environment survey provided evidence for H i extending over as much as 200 kpc in both groups. Our new, higher resolution observations reveal that the complex H i features detected by Arecibo are in reality two extraordinary long H i tails extending for ∼160 and 250 kpc, respectively, i.e., among the longest H i structures ever observed in groups of galaxies. Although in the case of RSCG42 the morphology and dynamics of the H i tail, as well as the optical properties of the group members, support a low-velocity tidal interac-tion scenario, less clear is the origin of the unique features associated with FGC1287. This galaxy displays an exceptionally long ‘dog leg ’ H i tail and the large distance from the X–ray emitting region of Abell 1367 makes a ram-pressure stripping scenario highly unlikely. At the same time a low-velocity tidal interaction seems unable to ex