Anomalous circular polarisation in the He I 1083.0 nm m ultiplet

1. Anomalous circular polarisation in the He I 1083.0 nm multiplet M. J. Martínez González A. Asensio Ramos, R. MansoSainz, C. Beck, L. Belluzzi

2. observations TIP @ VTT 1083.0 nm He I triplet – noise in pol. 10-3 Imax – spatial res. ≈ 0.6”

3. observations TIP @ VTT 1083.0 nm He I triplet – noise in pol. 10-3 Imax – spatial res. ≈ 0.6” regular V profile d

4. observations TIP @ VTT 1083.0 nm He I triplet – noise in pol. 10-3 Imax – spatial res. ≈ 0.6” anomalous V profile a regular V profile d

5. I Q U V

6. patches of net circular polarisation are consistent during more than 135 min d a c b

7. how to interpret net circular polarisation? Zeeman effect + radiative transfer effects (gradients of vel. and mag. Field) atomic orientation (population imbalance of σ components  symmetric contribution to Stokes V)

8. how to interpret net circular polarisation? Zeeman effect + radiative transfer effects (gradients of vel. and mag. Field) atomic orientation (population imbalance of σ components  symmetric contribution to Stokes V) VERY UNLIKELY one-lobbed V profiles due to gradients have half width of the intensity profile our observed V profiles are as broad as the intensity

9. how to interpret net circular polarisation? Zeeman effect + radiative transfer effects (gradients of vel. and mag. Field) atomic orientation (population imbalance of σ components  symmetric contribution to Stokes V) INVERSION OF 4 STOKES PROFILES 1) oneslabwithconstantproperties 2) 1 + atomicorientation 3) twoslabalongthe LOS withconstant properties 4) 3 + atomicorientation VERY UNLIKELY one-lobbed V profiles due to gradients have half width of the intensity profile our observed V profiles are as broad as the intensity

10. one slab with constant properties fits most of the prominence profiles, although some of them have non-zero net circular polarisation  transfer effects should be taken into account to properly fit those profiles subject to ambiguities Δλ

11. 1: one slab 2: oneslab + ad-hoc orientation of the rad. Field 3: two slab along LOS 4: two slab + ad-hoc orientation of the rad. Field Δλ [nm]

12. 1: one slab 2: oneslab + ad-hoc orientation of the rad. Field 3: two slab along LOS 4: two slab + ad-hoc orientation of the rad. Field Δλ [nm]

13. 1: one slab 2: oneslab + ad-hoc orientation of the rad. Field 3: two slab along LOS 4: two slab + ad-hoc orientation of the rad. Field Δλ [nm]

14. how to generate atomic orientation in the He 1083.0 nm line? alignment to orientation transfer mechanism by electric fields [LópezAriste et al. 2005] [atom non hydrogenic] differential excitation of σ components VERY UNLIKELY

15. how to generate atomic orientation in the He 1083.0 nm line? alignment to orientation transfer mechanism by electric fields [LópezAriste et al. 2005] [atom non hydrogenic] differential excitation of σ components a) illuminating the atoms with circular polarisation + relative vel. atom-rad. b) splittingthetransition anddiferentially illuminatingtheσcomp. VERY UNLIKELY scatterers embedded in 100 G underlying photosphere 1 kG inferred value

16. how to generate atomic orientation in the He 1083.0 nm line? alignment to orientation transfer mechanism by electric fields [LópezAriste et al. 2005] [atom non hydrogenic] differential excitation of σ components a) illuminating the atoms with circular polarisation + relative vel. atom-rad. prominences are found in neutral lines  cancelations b) splittingthetransition anddiferentially illuminatingtheσcomp. orientation of the order of magnitudof the inferred one is achieved with 8-10 km s-1 (vel. easily found in spicules) VERY UNLIKELY MOST PROBABLE UNLIKELY

17. Conclusions Stokes V profiles in spicules have a large amount of NCP (mostly one-lobbed) We reproduce them with 2 magnetized components and orientation of the incoming radiation field. The orientation needed is of 0.06-0.1% The most likely scenario to generate this orientation are dynamical processes In the presence of magnetic fields.

18. thank you!