Modelling the incomplete Paschen - Back effect in the spectra of magnetic Ap stars
نویسنده
چکیده
We present first results of a systematic investigation of the incomplete Paschen-Back effect in magnetic Ap stars. A short overview of the theory is followed by a demonstration of how level splittings and component strengths change with magnetic field strength for some lines of special astrophysical interest. Requirements are set out for a code which allows the calculation of full Stokes spectra in the Paschen-Back regime and the behaviour of Stokes I and V profiles of transitions in the multiplet 74 of Fe ii is discussed in some detail. It is shown that the incomplete Paschen-Back effect can lead to noticeable line shifts which strongly depend on total multiplet strength, magnetic field strength and field direction. Ghost components (which violate the normal selection rule on J) show up in strong magnetic fields but are probably unobservable. Finally it is shown that measurements of the integrated magnetic field modulus Hs are not adversely affected by the Paschen-Back effect, and that there is a potential problem in (magnetic) Doppler mapping if lines in the Paschen-Back regime are treated in the Zeeman approximation.
منابع مشابه
A ug 2 00 4 Signatures of Incomplete Paschen - Back Splitting in the Polarization Profiles of the He
We investigate the formation of polarization profiles induced by a magnetic field in the He I multiplet at 10830 Å. Our analysis considers the Zeeman splitting in the incomplete Paschen-Back regime. The effects turn out to be important and produce measurable signatures on the profiles, even for fields significantly weaker than the level-crossing field (∼400 G). When compared to profiles calcula...
متن کاملA search for radial magnetic field gradients in Ap atmospheres
For the first time the possible presence of radial gradients of magnetic fields in the atmospheres of three magnetic Ap stars has been critically examined by measurements of the mean magnetic field modulus from spectral lines resolved into magnetically split components lying on the different sides of the Balmer jump. A number of useful diagnostic lines below and above the Balmer discontinuity, ...
متن کاملTheory and Modeling of the Zeeman and Paschen-Back effects in Molecular Lines
This paper describes a very general approach to the calculation of the Zeeman splitting effect produced by an external magnetic field on the rotational levels of diatomic molecules. The method is valid for arbitrary values of the total electronic spin and of the magnetic field strength -that is, it holds for molecular electronic states of any multiplicity and for both the Zeeman and incomplete ...
متن کاملDifferent Magnetic Field Distributions in Deformed Neutron Stars
In this work, we review the formalism which would allow us to model magnetically deformed neutron stars. We study the effect of different magnetic field configurations on the equation of state (EoS) and the structure of such stars. For this aim, the EoS of magnetars is acquired by using the lowest order constraint variational (LOCV) method and employing the AV18 potential....
متن کاملLetter to the Editor Successful spectral synthesis of Zeeman-split molecular bands in sunspot spectra
We present the first spectral synthesis of Zeemansplit Stokes profiles of the MgH A2Π–X2Σ green system and TiO γ-system. The calculations involve different regimes of the molecular Zeeman effect, up to the complete Paschen-Back effect for individual lines. The synthetic spectra are compared with observations of Stokes I and V in sunspot umbrae. We find that although the Stokes I spectra are rea...
متن کامل