On the nature of the NGC 1275 system

Subarcsecond images, taken in B, R, and H alpha filters, and area spectrosc opy obtained with the WIYN 3.5 m telescope provide the basis for an investi gation of the unusual structures in the stellar body and ionized gas in and around the Perseus Cluster central galaxy NGC 1275. Our H alpha filter is tuned to gas at the velocity of NGC 1275, revealing complex, probably unres olved, small-scale features in the extended ionized gas, located up to 50 h (100)(-1) kpc from NGC 1275. The mean H alpha surface brightness varies lit tle along the outer filaments; this, together with the complex excitation s tate demonstrated by spectra, imply that the filaments are likely to be tub es, or ribbons, of gas. The morphology, location, and inferred physical par ameters of the gas in the filaments are consistent with a model, whereby th e filaments form through compression of the intracluster gas by relativisti c plasma emitted from the active nucleus of NGC 1275. Imaging spectroscopy with the DensePak fiber array on WIYN suggests partial rotational support o f the inner component of low-velocity ionized gas. Our broadband data is us ed to derive color maps of the stellar distribution and also to investigate asymmetries in the stellar surface brightness. We confirm and extend evide nce for features in the stellar body of NGC 1275 and identify outer stellar regions containing very blue, probably very young, star clusters. We inter pret these as evidence for recent accretion of a gas-rich system, with subs equent star formation. Other star clusters are identified, some of which ar e possibly associated with the high-velocity 8200 km s(-1) emission-line sy stem being in the same projected location. We suggest that two main process es, which may be causally connected, are responsible for the rich phenomeno logy of the NGC 1275 system-NGC 1275 experienced a recent merger and/or int eraction with a group of gas-rich galaxies, and recent outflows from its AG N have compressed the intracluster gas and perhaps the gas in the infalling galaxies to produce a complex web of filaments.