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VERSION:2.0
PRODID:icalendar-ruby
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260818T114043Z
UID:https://www.mps.mpg.de/events/18582/7840830
DTSTART:20190509T090000Z
DTEND:20190509T100000Z
CLASS:PUBLIC
CREATED:20190502T134108Z
DESCRIPTION: Since the work of Carlin et al. (2012)\, more studies have inv
 estigated\, with the help of MHD models of the solar chromosphere\, the be
 havior of scattering linear polarization (LP) in presence of macroscopic m
 otions and weak magnetic fields. The results of the spatio-temporal simula
 tions revealed a variable spectral morphology in the polarization of chrom
 ospheric lines\, as well as modulations of LP amplitude that affect Hanle 
 diagnosis\, and also several situations with clear potential for diagnosin
 g solar and stellar atmospheres. While much of these results resorts in th
 e dynamic variations of radiation field anisotropy along the (also dynamic
 ) formation region\, they also pose new questions that seem to transcend t
 he role of the anisotropy. On the other hand\, two problems slow down furt
 her research in this area. One is the SNR reached with current telescopes\
 , which is insufficient to compare observations with time-resolved simulat
 ions of scattering polarization. And the other is the extension and comple
 xity of the formation region of the polarization signals\, which often dem
 ands analysis of multidimensional simulations to extract conclusions. In t
 his regard\, I seek to develop a standard model for polarization that is p
 recise enough to explain the signals but simple enough to provide analyses
  without relying in MHD models. We will start this seminar by summarizing 
 the physical situation concerning the formation of dynamical LP in the ext
 ernal solar layers and by supporting the need of investigating the circula
 r polarization. We will then focus on the novel exploration of NLTE circul
 ar polarization considering atomic orientation and velocity gradients. Thi
 s approach leads to a better understanding of the formation of polarizatio
 n by avoiding the limb-darkening modulation (introduced by the anisotropy 
 in LP) and by allowing effective comparisons with observations. To explain
  this I will advance some observational results and I will present the fir
 st version of a simple and insightful model for explaining NLTE polarizati
 on signals. A particularity of the approach here proposed is the associati
 on of the zeroes of the emergent polarization spectrum with its morphology
  and with the properties of the scattering medium.\nVortragende(r): Edgar 
 S. Carlin 
LAST-MODIFIED:20260220T073313Z
LOCATION:Instituto de Astrofísica de Canarias (broadcasted at MPS)\, Raum:
  Auditorium
ORGANIZER;CN=Andreas Lagg:mailto:
SUMMARY:ESPOS: ESP Online Seminar: Formation and morphology of solar circul
 ar polarization with dichroism\, atomic polarization and velocity gradient
 s (Edgar S. Carlin)
URL;VALUE=URI:https://www.mps.mpg.de/events/18582/7840830
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