Volume 494, Number 2, February I 2009
|Page(s)||489 - 508|
|Published online||22 December 2008|
Kinematic modeling of disk galaxies
III. The warped “Spindle” NGC 2685
Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo, The Netherlands e-mail: [jozsa;oosterloo;morganti]@astron.nl
2 Kapteyn Astronomical Institute, Univ. Groningen, Postbus 800, 9700 AV Groningen, The Netherlands
3 Argelander-Institut für Astronomie (AIfA), Univ. Bonn, Auf dem Hügel 71, 53121 Bonn, Germany e-mail: [uklein;erben]@astro.uni-bonn.de
Accepted: 10 October 2008
This is the third of a series of papers in which the structure and kinematics of disk galaxies is studied. By employing direct tilted-ring fits to the data cube as introduced in Paper I, we analyzed the “Spindle” galaxy NGC 2685, previously regarded as a two-ringed polar ring galaxy. Deep H I and optical (i'-band) observations are presented. The H I observations strongly suggest that the gaseous structure of NGC 2685 does not consist of two separate mutually inclined regions, but forms a coherent, extremely warped disk, the appearance of two rings being due to projection effects. By comparing the H I total-intensity maps with the optical image, we demonstrate that at large radii a faint stellar disk is well aligned with the outer H I disk. The shape of the dust lanes obscuring the NE part of the inner stellar body indicates that, also at smaller radii, NGC 2685 possesses a disk containing gas, dust, and stars in which the various constituents are aligned. At smaller radii, this disk is kinematically decoupled from the central stellar body; hence, in the region of the bright, central stellar body, NGC 2685 appears to consist of two disks that share a common center, but have different orientation: a bright stellar lenticular body apparently devoid of dust and gas, and a heavily warped low-surface brightness disk containing stars, gas, and dust. The low-surface-brightness disk changes its orientation gradually and at large radii assumes the orientation of the central stellar S0 disk. Since, according to our analysis, the intrinsic orientation of the low-surface-brightness disk changes through 70°, the gaseous disk is coherent, and is at no radius oriented perpendicularly with respect to the central stellar body, NGC 2685 is not likely to be a classical polar-ring galaxy.
Key words: galaxies: kinematics and dynamics / galaxies: structure / galaxies: ISM / galaxies: peculiar / galaxies: individual: NGC 2685
© ESO, 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.