NGC 7129 FIRS 2: an intermediate-mass counterpart of Class 0 objects

We present JCMT (sub)millimetre observations of the young source NGC 7129 FIRS 2 and HIRAS maps of the whole NGC 7129 region. The total integrated luminosity of FIRS 2 is approximate to 430 L.. Its spectral energy distribution is described by a single-temperature grey body with T = 35 K and beta = 0.9. The total mass is found to be similar to 6 M.. These and other properties indicate that FIRS 2 is an intermediate-mass counterpart of the low-mass Class 0 protostellar objects; in this sense, FIRS 2 is probably the youngest intermediate-mass object we know at present. The far-infrared emission of NGC 7129 is dominated by two sources: FIRS 1, which is located toward the HAeBe star LkH alpha 234, and FIRS 2. The cavity observed in the optical NGC 7129 reflection nebulosity and in radio emission lines is clearly observed in the HIRAS maps, particularly in the 25 mu m band. The total estimated luminosity of the region is approximate to 4.5 10(3) L., consistent with the idea that the dust is heated by the cluster of HAeBe stars in NGC 7129.