Study of 9 LRNe with various photometric data

Another LRN, AT 2011kp, is detected by JWST 12.5 years after the outburst. Its SED, with two excesses at 1.8 and 7.7{mu}m, can be explained by a cold (T~450K) dusty shell composed of amorphous carbon surrounding a cold expanded source, plus emission from the Pa{alpha} line. We constructed the [3.6]-[4.5] colour curves extending up to more than 7 years for six LRNe, which show a similar evolution: The MIR colour is ~-0.5mag before the optical maximum light, it becomes bluer after around one year, and then it gradually turns to redder colours in the following years before reaching [3.6]-[4.5]~+1.0mag 7 years after the outburst.

We also estimated the masses and the temperatures of newly formed dust years after the LRN onset. We find that LRNe produce dust masses of the order of (1-5)*10^-4^ (and up to 2*10^-3^) M_{Sun}_ between 7 and 13 years after the outbursts. Finally, we find that the remnants of LRNe detected years or decades after the merger tend to be expanded and cool objects, similar to red supergiant stars.