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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20141112T103000
DTEND;TZID=Atlantic/Canary:20141112T113000
UID:iactalks-684
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/684
CREATED:2014-11-12T10:30:00+00:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:On the origin of Exponential Radial Profiles in Disk Galaxies
DESCRIPTION:On the origin of Exponential Radial Profiles in Disk Galaxies\n
 Prof. Bruce G. Elmegreen\n\nThe exponential radial profiles of spiral gala
 xies have been observed  for decades with various explanations offered, bu
 t none of these  explanations hold up now that the profiles have been trac
 ed to 10 scale  lengths in some cases. Profiles with breaks also have thei
 r outer parts  remarkably close to exponential. This is true in both spira
 ls and  dwarfs, with a particular problem for non-barred dwarfs where ther
 e are  no strong torques or shears in the stellar disks for radial scatter
 ing.   We have shown that scattering from disk clumps can make exponential
 s,  and indeed dwarfs have fairly massive clumps and irregularities in the
 ir  HI distributions. Spiral waves also have clumps in the form of  persis
 tent wave enhancements at corotation and at points of wave  interference. 
  This talk reviews the observations of exponential  profiles and profile b
 reaks in spiral and dwarf galaxies, and considers  various theories to exp
 lain them.
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