HOT DUST IN THE ACTIVE NUCLEUS OF NGC-7469 PROBED BY ADAPTIVE OPTICS OBSERVATIONS

The use of adaptive optics has allowed to reach in the infrared an ang ular resolution around 0.35 '', allowing to study the temperature, mas s and distribution of the dust component within the 400 pc radius cent ral region of NGC 7469. We have obtained L and L' band images which sh ow an unresolved core (r<55 pc) embedded in an extended emission compo nent. Not to mention the ring of star formation, known to be present a t r similar to 1.5 '', which cannot be studied from this data set beca use of its quite low surface brightness and will not be discussed here . We find that about 55% of the 3.5 and 3.8 mu m flux across the 1.4 ' ' x 1.4 '' central region arises from the unresolved core. The hot and warm dust grain density in the extended component follows an r(-1.5) law, and the dust temperature ranges from 900 K (r similar to 130 pc) to similar to 300 K (r similar to 400 pc). The mass of hot (T=900 K) d ust within a r similar to 200 pc central region is similar to 0.05 M-. and it accounts for 36% of the 2.2 mu m emission in this region. Thes e results are in good agreement with a composite model of active nucle us including a parsec scale dusty torus surrounded by an extended hot dust region located in the NLR and heated by the central engine.