COMPLEX GASEOUS STRUCTURE IN THE NUCLEUS OF NGC-5252

Citation
Zi. Tsvetanov et al., COMPLEX GASEOUS STRUCTURE IN THE NUCLEUS OF NGC-5252, The Astrophysical journal, 458(1), 1996, pp. 172
Citations number
17
Categorie Soggetti
Astronomy & Astrophysics
Journal title
ISSN journal
0004637X
Volume
458
Issue
1
Year of publication
1996
Part
1
Database
ISI
SICI code
0004-637X(1996)458:1<172:CGSITN>2.0.ZU;2-C
Abstract
We present several Hubble Space Telescope (HST) WFPC2 emission-line an d continuum images of NGC 5252, a Seyfert 2 SO galaxy with a large-sca le ''ionization bi-cone.'' In the H alpha + [N 11] image, the nucleus is bracketed at similar to 0''.3 radii by two bright emission-line clu mps along P.A. = 35 degrees (similar to 20 degrees from the major axis of the large-scale stellar disk). These three knots dominate the emis sion in the innermost similar to 1'' (similar to 450 pc at 92 Mpc dist ance). Two major and several smaller spiral filaments, wound tightly c ounterclockwise, extend, similar to 3'' to the northwest and similar t o 4''.5 to the southeast of the nucleus. Several of these filaments ex tend from the two clumps near the nucleus, possibly indicating that th e three collinear knots comprise a bar. Our Fabry-Perot velocity map s hows that the spiral pattern is rotating, in a disk inclined significa ntly to both the galaxy stellar disk and the radio jets. The nuclear r adio jets appear to have no obvious association with the H alpha + [N II] filaments and clumps. Although most of the line flux is emitted wi thin the inward extrapolation of the large-scale ionization bi-cone, s ome of the H alpha + [N II] filaments extend beyond the cone boundarie s. A remarkable D-shaped pattern of obscuring dust is visible on the n orthwest side of the galaxy major axis. Most of the spiral filaments i n the H alpha + [N II] image also appear in the obscuration map. The e xtinction by the filaments requires a column density of N-H approximat e to 5 x 10(20) cm(-2). If the filaments are uniformly filled, both th e gas responsible for the extinction and the ionized gas responsible f or the emission have number densities of a few cm(-3).