Show simple item record

dc.contributor.author
Shapiro, Alexander I.
dc.contributor.author
Fluri, D.M.
dc.contributor.author
Berdyugina, Svetlana V.
dc.contributor.author
Bianda, Michèle
dc.contributor.author
Ramelli, Renzo
dc.date.accessioned
2020-07-03T08:12:15Z
dc.date.available
2017-06-09T13:38:30Z
dc.date.available
2020-07-03T08:12:15Z
dc.date.issued
2011-05
dc.identifier.issn
0004-6361
dc.identifier.issn
1432-0746
dc.identifier.other
10.1051/0004-6361/200811299
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/39553
dc.description.abstract
Context. The solar surface magnetic field is connected with and even controls most of the solar activity phenomena. Zeeman effect diagnostics allow for measuring only a small fraction of the fractal-like structured magnetic field. The remaining hidden magnetic fields can only be accessed with the Hanle effect. Aims. Molecular lines are very convenient for applying the Hanle effect diagnostics thanks to the broad range of magnetic sensitivities in a narrow spectral region. With the UV version of the Zurich Imaging Polarimeter ZIMPOL II installed at the 45 cm telescope of the Istituto Ricerche Solari Locarno (IRSOL), we simultaneously observed intensity and linear polarization center-to-limb variations in two spectral regions containing the (0, 0) and (1, 1) bandheads of the CN B2Σ - X2Σ system. Here we present an analysis of these observations. Methods. We have implemented coherent scattering in molecular lines into an NLTE radiative transfer code. A two-step approach was used. First, we separately solved the statistical equilibrium equations and compute opacities and intensity while neglecting polarization. Then we used these quantities as input for calculating scattering polarization and the Hanle effect. Results. We have found that it is impossible to fit the intensity and polarization simultaneously at different limb angles in the framework of standard 1D modeling. The atmosphere models that provide correct intensity center-to-limb variations fail to fit linear polarization center-to-limb variations due to lacking radiation-field anisotropy. We had to increase the anisotropy by means of a specially introduced free parameter. This allows us to successfully interpret our observations. We discuss possible reasons for underestimating the anisotropy in the 1D modeling.
en_US
dc.language.iso
en
en_US
dc.publisher
EDP Sciences
en_US
dc.subject
Line: formation
en_US
dc.subject
Sun: magnetic fields
en_US
dc.subject
Molecular processes
en_US
dc.subject
Polarization
en_US
dc.subject
Radiative transfer
en_US
dc.subject
Scattering
en_US
dc.title
NLTE modeling of Stokes vector center-to-limb variations in the CN violet system
en_US
dc.type
Journal Article
dc.date.published
2011-04-20
ethz.journal.title
Astronomy & Astrophysics
ethz.journal.volume
529
en_US
ethz.journal.abbreviated
Astron. Astrophys.
ethz.pages.start
A139
en_US
ethz.size
14 p.
en_US
ethz.identifier.wos
ethz.identifier.nebis
000021324
ethz.publication.place
Les Ulis
en_US
ethz.publication.status
published
en_US
ethz.date.deposited
2017-06-09T13:38:41Z
ethz.source
ECIT
ethz.identifier.importid
imp59364e648719b39480
ethz.ecitpid
pub:63697
ethz.eth
yes
en_US
ethz.availability
Metadata only
en_US
ethz.rosetta.installDate
2017-07-15T20:56:09Z
ethz.rosetta.lastUpdated
2020-07-03T08:12:26Z
ethz.rosetta.versionExported
true
ethz.COinS
ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.atitle=NLTE%20modeling%20of%20Stokes%20vector%20center-to-limb%20variations%20in%20the%20CN%20violet%20system&rft.jtitle=Astronomy%20&%20Astrophysics&rft.date=2011-05&rft.volume=529&rft.spage=A139&rft.issn=0004-6361&1432-0746&rft.au=Shapiro,%20Alexander%20I.&Fluri,%20D.M.&Berdyugina,%20Svetlana%20V.&Bianda,%20Mich%C3%A8le&Ramelli,%20Renzo&rft.genre=article&rft_id=info:doi/10.1051/0004-6361/200811299&
 Search print copy at ETH Library

Files in this item

FilesSizeFormatOpen in viewer

There are no files associated with this item.

Publication type

Show simple item record