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Two states of the nucleus of the NGC 4151 Galaxy quiet and activeстатья
- Авторы: Kotov V.A., Lyuty V.M., Metlov V.G., Haneychuk V.I.
- Журнал: Kinematika i Fizika Nebesnykh Tel
- Том: 16
- Номер: 6
- Год издания: 2000
- Первая страница: 558
- Последняя страница: 569
- Аннотация: The most interesting phenomenon in the studies of active galactic nuclei is their rapid variability over one night whose origin remains mysterious, and of special interest is the search for the presence of a periodic component. The oscillation with the period P0 ≈ 160.010 min was found earlier in the emission of the nucleus of the Seyfert galaxy NGC 4151, but its authenticity is often doubted. The reasons for the scepticism are a small amplitude of the signal and the fact that the oscillation is absent during some nights. In 1985-1996 the observers of the P. K. Sternberg State Astronomical Institute and the Crimean Astrophysical Observatory carried out long series of photometric observations of NGC 4151 (in all, 39 and 51 nights in the U and V bands, respectively). Less than a half of the nights a significant variability over a night which exceeded 0.03-mag threshold (it was treated with no relation to any a priori periodicity). But the most important is that the P0-oscillation was clearly seen exactly during those "active" nights; other, "quiet", nights did not reveal any noticeable periodic signal. The mean harmonic amplitude of the P0 -oscillation during the active state of the NGC 4151 nucleus is found to be about 0.009m (U-band), while it is not larger than 0.0008m in the same band during the quiet state. The nature of such a strange modulation is unknown. The arguments are given in favour of a cosmological origin of the P0-oscillation.
- Добавил в систему: Метлов Владимир Георгиевич