BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//ZContent.net//ZapCalLib 1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20080716T000000
DTEND;TZID=Atlantic/Canary:20080716T010000
UID:iactalks-159
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/159
CREATED:2008-07-16T00:00:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:Warps in galactic H I disks
DESCRIPTION:Warps in galactic H I disks\nDr. Gyula Jozsa\n\nWarps of disk g
 alaxies are ubiquitous. In almost every disk galaxy a bending of the disk 
 occurs where the stars fade away and hence where the dark matter halo beco
 mes dominant. A clear understanding of this phenomenon has not been reache
 d yet. Analysing H I observations of a small sample of symmetric, warped d
 isk galaxies we found that they exhibit a two-disk structure, the warp bei
 ng the transition from the inner flat disk to an outer, inclined one. At t
 he transition radius, the rotation curve changes. This points towards symm
 etric warps being a long-lived phenomenon reflecting an internal change in
  the structure of the Dark Matter halo.\n\nWhile warps usually occur where
  the stellar disks fade, examples of extreme warps are known that commence
  already at the centre of galaxies.  One is present in the neutral gas dis
 k of the "Spindle Galaxy "NGC 2685, formerly thought of as being a two-rin
 ged polar ring galaxy.  Utilising deep HI observations, we found that the 
 two-ringed appearance is due to projection effects and that it rather poss
 esses one coherent,extremely warped HI disk. Our success in fitting a tilt
 ed-ring model to the HI component, and, with that, assuming circular orbit
 s of the tracer material, and the shape of the fitted rotation curve hint 
 towards a rather spherical shape of the overall potential.\n\n
END:VEVENT
END:VCALENDAR