12/04/01
Combes Francoise	Observatoire de Paris
61 Av. de l'Observatoire	SF2A- PNC- PNG-
75014	Paris, France

Presentation 1 : Poster
Molecular gas in the double-barred Seyfert 2 galaxy NGC 5728 (PNG)
Combes F. (1), Leon S. (2); (1) Obs Paris, France (2) Koeln, Germany
We present CO(1-0) and CO(2-1) maps of the Seyfert galaxy NGC 5728. Although a stellar nuclear bar structure is clearly identified in the near-infrared images in the central 10", inside the ring identified as the ILR of the primary bar, there is no nuclear bar structure in the molecular gas. Instead, the CO emission reveals an elongated structure, 15" in length, beginning at the nucleus defined by the radio center) aligned with the jet/ionisation cone, at a PA of 127 degrees. This morphology, not frequently observed in Seyfert galaxies, may be interpreted in terms of enhanced CO excitation along the walls of the cone. Kinematical perturbations along the cone support this scenario. At larger-scale, CO emission is tracing the primary bar, and outer ring structure. The total molecular mass, estimated from the CO emission, is M(H2) = 3.1 E9 Mo.
Presentation 2 : Poster
Molecular gas in the 3-ringed Seyfert/Liner galaxy NGC 7217 (PNG)
Combes F.(1), Garcia-Burillo S.(2), Boone F.(1), Hunt L.K.(3), Leon S.(4) Eckart A.(4), Baker A.(5), Tacconi L.(5), Englmaier P.(5), Schinnerer E.(6), Neri R.(7)
(1) LERMA, Observatoire de Paris, France (2) Observatorio Astronomico Nacional, Madrid, Spain (3) Osservatorio Astrofisico di Arcetri, Italy (4) I. Physikalisches Institut, Universitaet zu Koeln, Germany (5) MPE, Garching, Germany (6) Caltech, USA (7) IRAM, Grenoble, France
We present CO(1-0) and CO(2-1) maps of the Seyfert galaxy NGC 7217, performed with the IRAM interferometer, at 3" and 1.5" resolution respectively. The nuclear ring (at r=10"=0.8kpc) is predominant in the CO maps, with a remarquable density gradient between the depleted region inside the ring and the inner border of the ring. The CO nuclear ring is broad (200-300pc) significantly broader than the dust lane ring. The CO(2-1)/CO(1-0) ratio is around 1 typical of optically thick gas, with high density. The overall morphology of the ring is quite circular, with no evidence of non-circular velocities. In the CO(2-1) map, a central concentration might be associated to the circumnuclear ring of ionised gas detected inside r=3" by Sil'chenko and Afanasiev (2000), and interpreted as a polar ring. Our interpretation is more in terms of a bar/spiral structure, in the same plane as the global galaxy, but affected by non-circular motions, resulting in a characteristic S-shape of the isovels. This nuclear bar/spiral structure, clearly seen in V-I HST colour image, is essentially gaseous, and might be explained with acoustic waves.

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