Extended very cold dust in the interacting HI ring galaxy pair NGC 2293 / 2292

The LGG 138 galaxy group members NGC 2292 and NGC 2293 were imaged with ISOPHOT in the far-infrared (FIR) at {60 μ m}, {100 μ m}, and {200 μ m}. While no FIR emission is seen at {60 μ m}, and only very low level emission is present at {100 μ m}, compact FIR emission from both NGC 2292 and NGC 2293 galaxy centres and extended emission likely associated with tidally removed dust and the HI ring surrounding NGC 2292 / 2293 is strongly detected at {200 μ m}. Additionally, a compact FIR source associated with the neighbouring galaxy NGC 2295 is strongly detected at {200 μ m}. Remarkably, none of these three galaxies have been detected individually in 21 cm HI emission. The steeply rising far-infrared spectral energy distribution of the apparently interacting NGC 2292 / 2293 pair towards longer wavelengths indicates the thermal emission of very cold dust with a temperature of 13 K, much lower than typical values of interacting systems or even quiescent spiral galaxies. The FIR data of this galaxy group clearly shows for the first time that there could be FIR dust emission not accompanied by HI, that dust even in an interacting system can have a very low dust temperature, and furthermore that gravitational interaction can give rise to an extended diffuse dust distribution.