Are Some Inner Spiral Disks Counter-Rotating or are They Warped?

Díaz, R. J.; Dottori, H.; Mediavilla, E.
Bibliographical reference

XI IAU Regional Latin American Meeting of Astronomy (Eds. L. Infante & M. Rubio) Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias) Vol. 26, pp. 179

Advertised on:
6
2006
Number of authors
3
IAC number of authors
0
Citations
0
Refereed citations
0
Description
Simulation of encounters of disk galaxies (Barnes 2002, MNRAS, 333, 481) shows that the newly formed disks are often warped, many have rather complex kinematics, and roughly a quarter have counter-rotating or otherwise decoupled central components. Recent integral-field observations of the S0 galaxy NGC 7332 added to broad-band ground-based and Hubble Space Telescope (HST) photometry seem to indicate a double-disc structure in this galaxy. Furthermore, the SAURON two-dimensional stellar kinematic maps is interpreted as been produced by a cold counter-rotating stellar component within the central 250 pc of NGC 7332. The Hβ and [O III] emission line maps show that the ionized gas has a complex morphology and kinematics, including both a component counter-rotating with respect to the stars and a fainter corotating one (Falcon-Barroso et al. 2004, MNRAS, 350, 35). Other galaxies also show this type of counter-rotating inner disk at tens or hundredths parsecs scale, as the case of NGC 253 (Zhao et al. 2001, ASPCP, 240, 404). In this contribution we analyze the inner disk warp as an alternative explanation to counter-rotation to explain peculiar forms of the rotation curves ascribed to counter-rotation. In fact, inner disks warps with position angle of their line of nodes different from that of the large disks, both with a small inclination with respect to the plane of the sky, may be misunderstood as been produced by counter-rotation.