NGC 7469. The perfect triptych: interaction, circumnuclear starbur stand black hole?

Optical photometric observations of the Seyfert nucleus NGC 7469 are reported. In August 1990, all‐night monitoring was done during 5 photometric nights (∼29 hours) using differential photometry techniques. After a very thorough discrimination of errors and their analysis, we conclude that random variability was present during the first four nights with average amplitude ∼0m.040 (at a σ≥4.5 level) on averagetime scales of ∼13 minutes. During the fifth night the variability nearly disappeared. A maximum Δm∼0m.081 (9.3σ) was observed in Δt=2.35 hrs. The average fluctuations imply an 8% variation in the luminosity of the unresolved nucleus and a rate of change of ΔLvar/Δt∼6×1037 erg sec−2. Our observations favor the black hole model and may be explained by the development of instabilities in the accretion disk. There is also strong evidence for tidal interaction of this galaxy with it companion, IC 5283, and for the existence of a circumnuclear starburst, making NGC 7469 a most suitable galaxy to study the relation of all these phenomena.