Prominent Bar Research Articles

Broadband imaging of eight isolated (?) Seyfert galaxies

view Abstract Citations (12) References (55) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Broadband Imaging of Eight Isolated (?) Seyfert Galaxies Xanthopoulos, E. ; De Robertis, M. M. Abstract Tidal triggering by companion galaxies has been proposed as the main mechanism responsible for nuclear activity in Seyfert galaxies. However, although Seyfert galaxies show a tendency to occur in multiple systems, there is a small fraction of these galaxies that appear to be completely isolated. For eight interaction activity class 1 Seyfert galaxies ["completely isolated" as defined by Dahari (Ph.D. thesis, University of California, Santa Cruz, 1984a)], we obtained CCD V images to search for possible faint or hidden companions or other signs of distortions- evidence of a recent interaction. Two galaxies appear to have distant companions. More than 3/4 of the sample contains some type of morphological asymmetry. One galaxy (Mrk 686) shows a very prominent bar and three more (Mrk 1469, Mrk 885, and NGC 4235) show a hint of a bar. Mrk 486 appears to have a jetlike distortion. Only Mrk 1388 appears to be symmetrical. Publication: The Astronomical Journal Pub Date: December 1991 DOI: 10.1086/116020 Bibcode: 1991AJ....102.1980X Keywords: Active Galactic Nuclei; Galactic Radiation; Seyfert Galaxies; Broadband; Galactic Clusters; Astrophysics; GALAXIES: SEYFERT full text sources ADS | data products SIMBAD (12) NED (9)

Morphology and Luminosity Distribution of Seyfert Galaxies

V and I CCD images for 13 Seyfert galaxies have been obtained at the Cassegrain focus of the JKT at the Roque de los Muchachos Observatory, Canary Islands. Integrated V and I magnitudes were obtained sampling the intensity of each galaxy in a circular area, up to a radial distance R at which the V surface brightness is 24 mag/sq arcsec. Mean luminosities MV = −21.89 and MI = −22.92 have been calculated adopting the galaxian radial velocities given by Adams (1977) and Ho = 55 kms−1 Mpc−1. By using elliptically averaged V and I luminosity profiles and the most outstanding morphological features from isophote maps we can distinguish two groups: 1) Galaxies with prominent bulge (Mk 50, Mk 124, Mk 348 and 3C227) where almost the entire profile is fitted by an r−1/4 law and no evidence for an exponential disk is found; some have a very diffuse external structure, like Mk 50 and Mk 348; and 2) Spiral galaxies (Mk 9, Mk 10, Mk 79, Mk 110, Mk 352, Mk 358 and Mk 618) showing spiral arms and exponential disks; most of them have also a prominent bar. Mk 42, whose luminosity profiles are strongly disturbed by a bright external ring, and NGC 985 a galaxy with a single arm, were both included in this group.

COLLECTIVE MOVEMENT OF SEDIMENT IN LITTORAL ENVIRONMENT

Collective movements of sediment occur in the form of sand waves m the nearshore zone and affect beach topography to a significant extent. Bar-type sand waves move only in the onshore direction and account for various accretive profiles on the subaerial beach. When the beach is eroded, these sand waves are simply disintegrated on the subaerial beach, instead of migrating back in the form of sand waves. These characteristics of bar-type sand waves help explain dynamic behavior of beach profiles with respect to profile configuration, sediment storage, and beach width. Cusp-type sand waves are considered to be a product of interaction between longshore currents and an erodible bed. Their presence causes variability in beach profiles along the shore between those containing a prominent bar and those without a bar. Migration of these sand waves may well produce pulsational transfer of material along the shore.