SIMBAD references

It is well known that the IRAS colors of planetary nebulae (PNs) are very similar to blackbody colors. Taking account of this characteristic, we define a new method to obtain some information about the distance to PNs by blackbody fitting of IRAS four-band fluxes, assuming these fluxes are due to thermal emission from the nebular dust envelope. The fit should have two free parameters–the dust temperature T_D and the distance-dependent ``scaling factor'' A–under the assumption of uniform dust mass. We find that the A-values have a good correlation with published distances. The scaling factor A could be a more effective distance scale than others, because many PNs have been detected as IRAS sources and the extinction of IRAS fluxes is not so severe, and is known. We also find that T_D is concentrated between 100 and 200 K, with a typical value of about 150 K.