Polarized Scattering With Paschen-Back Effect, Hyperfine Structure, and Partial Frequency Redistribution in Magnetized Stellar Atmospheres

Sowmya, K.; Nagendra, K. N.; Stenflo, J. O.; Sampoorna, M.

doi:10.1088/0004-637x/786/2/150

Cited by 15 publications

(33 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A rapid transformation in the eigenvector basis takes place around the region of avoided crossing. This is described in Bommier (1980) and in LL04 (see also Sowmya et al 2014aSowmya et al , 2014b.…”

Section: Level-crossings and Avoided Crossingsmentioning

confidence: 80%

“…When I s = 0, Equation (12) reduces to the PRD matrix for J state interference alone (see Equation (11) of Sowmya et al 2014a). When FS is neglected, Equation (12) reduces to the expression of RM for pure F state interference (see Equation (16) of Sowmya et al 2014b). When we neglect both FS and HFS, we recover RM for the L L L a b a   transition (analogous to a two-level atom case) in the presence of a magnetic field.…”

Section: The Redistribution Matrix For the Combined J And F State Intmentioning

confidence: 99%

See 1 more Smart Citation

Polarized Scattering of Light for Arbitrary Magnetic Fields With Level-Crossings From the Combination of Hyperfine and Fine Structure Splittings

Sowmya

Nagendra

Sampoorna

et al. 2015

ApJ

Self Cite

View full text Add to dashboard Cite

Interference between magnetic substates of the hyperfine structure states belonging to different fine structure states of the same term influences the polarization for some of the diagnostically important lines of the Sunʼs spectrum, like the sodium and lithium doublets. The polarization signatures of this combined interference contain information on the properties of the solar magnetic fields. Motivated by this, in the present paper, we study the problem of polarized scattering on a two-term atom with hyperfine structure by accounting for the partial redistribution in the photon frequencies arising due to the Doppler motions of the atoms. We consider the scattering atoms to be under the influence of a magnetic field of arbitrary strength and develop a formalism based on the Kramers-Heisenberg approach to calculate the scattering cross section for this process. We explore the rich polarization effects that arise from various level-crossings in the Paschen-Back regime in a single scattering case using the lithium atomic system as a concrete example that is relevant to the Sun.

show abstract

Section: Level-crossings and Avoided Crossingsmentioning

confidence: 80%

Section: The Redistribution Matrix For the Combined J And F State Intmentioning

confidence: 99%

Polarized Scattering of Light for Arbitrary Magnetic Fields With Level-Crossings From the Combination of Hyperfine and Fine Structure Splittings

Sowmya

Nagendra

Sampoorna

et al. 2015

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…This is not the case in Figure 3(b) as the magnetic splittings involved are too small to produce any significant broadening. Q/I decreases as the field strength is increased followed by an increase beyond the value at B = 0 (see Figure 3(a)), which is attributed to the anti-level crossing effect described in detail in Sowmya et al (2014a). In Figure 3(b) we only see a decrease in Q/I with the increasing field strength followed by an increase.…”

Section: Effect Of a Vertical Magnetic Fieldmentioning

confidence: 67%

“…This is because both the fine and hyperfine structure states of this line system exhibit PBE for the field strengths encountered in the solar atmosphere. Therefore we apply the partial redistribution scattering theory developed for PBE in fine structure states (Sowmya et al 2014b) and for PBE in hyperfine structure states (Sowmya et al 2014a) to study the signatures of PBE in the Li i D line system. We consider both the stable isotopes of Li, namely 6 Li and 7 Li.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Paschen-Back effect involving atomic fine and hyperfine structure states

Sowmya¹,

Nagendra²,

Sampoorna³

et al. 2014

Proc. IAU

Self Cite

View full text Add to dashboard Cite

Abstract. The linear polarization in spectral lines produced by coherent scattering is significantly modified by the quantum interference between the atomic states in the presence of a magnetic field. When magnetic fields produce a splitting which is of the order of or greater than the fine or hyperfine structure splittings, we enter the Paschen-Back effect (PBE) regime, in which the magnetic field dependence of the Zeeman splittings and transition amplitudes becomes non-linear. In general, PBE occurs for sufficiently strong fields when the fine structure states are involved and for weak fields in the case of hyperfine structure states. In this work, we apply the recently developed theory of PBE in the atomic fine and hyperfine structure states including the effects of partial frequency redistribution to the case of Li i 6708Å doublet. We explore the signatures of PBE in a single scattering event and their applicability to the solar magnetic field diagnostics.

show abstract

On the importance of partial frequency redistribution in modeling the scattering polarization

Nagendra

2014

Proc. IAU

Self Cite

View full text Add to dashboard Cite

It is well-known that partial frequency redistribution (PRD) is the basic physical mechanism to correctly describe radiative transfer in spectral lines. In the case of polarized line scattering, the PRD becomes particularly important to describe the line-wing polarization, instead of the well-known mechanism of complete redistribution (CRD). Historically, the two-level atom PRD scattering matrices for polarized line scattering were first derived in the 1970's, and later generalized to the case of arbitrary fields in 1997. The latter formulation of the PRD matrices have subsequently been used in the solution of the line transfer equation to successfully model the non-magnetic (resonance scattering) and the magnetic (Hanle scattering) polarization observations. In recent years, using the Kramers-Heisenberg approach, we formulated PRD matrices for various physical mechanisms like quantum interference involving fine- and hyperfine-structure states in a two-term atom. The effect of collisions is included in an approximate way. We have used these PRD matrices to model the observed linear polarization in several interesting lines of the Second Solar Spectrum. In this paper I present a few results which highlight the importance of PRD in the interpretation of the polarized Stokes profiles.

show abstract

Polarized Scattering With Paschen-Back Effect, Hyperfine Structure, and Partial Frequency Redistribution in Magnetized Stellar Atmospheres

Cited by 15 publications

References 24 publications

Polarized Scattering of Light for Arbitrary Magnetic Fields With Level-Crossings From the Combination of Hyperfine and Fine Structure Splittings

Polarized Scattering of Light for Arbitrary Magnetic Fields With Level-Crossings From the Combination of Hyperfine and Fine Structure Splittings

Paschen-Back effect involving atomic fine and hyperfine structure states

On the importance of partial frequency redistribution in modeling the scattering polarization

Contact Info

Product

Resources

About