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Penumbral-like Structures in the Photosphere as a Manifestation of Flux Emergence

Penumbral-like Structures in the Photosphere as a Manifestation of Flux Emergence. Salvo L. Guglielmino 1 , Francesca Zuccarello 1 & Paolo Romano 2. 1 Dipartimento di Fisica e Astronomia – Università di Catania, Italy 2 INAF – Osservatorio Astrofisico di Catania, Italy

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Penumbral-like Structures in the Photosphere as a Manifestation of Flux Emergence

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  1. Penumbral-like Structures in the Photosphere as a Manifestation of Flux Emergence Salvo L. Guglielmino1, Francesca Zuccarello1 & Paolo Romano2 1Dipartimento di Fisica e Astronomia – Università di Catania, Italy2INAF – Osservatorio Astrofisico di Catania, Italy 14thEuropeanSolarPhysics MeetingTrinity College, Dublin, 8 – 12 September2014

  2. Magneticfluxemergence A complete studyofmagneticfluxemergence, interaction, and diffusionshould take into account some “anomalies” In the photospherewe can observefluxconcentrationsovermanyspatialscales sunspots, pores, ephemeralregions, granular loops … but rare observationsalso show: orphanpenumbraeandnakedsunspots

  3. Why “orphanpenumbrae”? Orphanpenumbraeare bundlesoffilamentarystructures, verysimilartosunspotpenumbralfilaments, butthat are notadjacenttoanysunspot umbra The orphanpenumbrashows the samemotionsobserved in the sunspotpenumbra Zirin & Wang (1991)

  4. Formationmechanism photospheric manifestation of a flux rope trapped in the photosphere (Kuckein et al., 2012a,b) the result of an emerging Ω-loop trapped in the photosphere by overlying canopy fields (Lim et al., 2013) the effect of submerging horizontal field in flattened Ω-loops (Jurčak et al., 2014)

  5. Modelsofpenumbralfilamentformation MHD simulations (Rempel 2012): magnetoconvection in presenceofhorizontalfieldsisabletoformpenumbralstructureswhen a magneticcanopyoverlies the fluxregion

  6. 1 2 3 4 5 6 7 Observationsofpenumbralfilamentformation • Romano et al. (2013, 2014) find a 3"-5" width annular zone around a pore, a few hours before the penumbra formation • magnetic field with uncombed structure • several patches (≈1") with upflows and rather vertical fields See our poster!!! High resolution observations of the formation of a sunspot penumbra The penumbral filament formation results from the bending of the field lines of the magnetic canopy overlying the pore

  7. Answer: evolution and spectropolarimetry LARGE orphan penumbrae in NOAA 11089 Zuccarello et al. (2014) ApJ, 787, 57 SMALL orphan penumbra inNOAA 11391 Guglielmino et al. (2014)ApJL, 786, L22

  8. NOAA 11089 • Visible from 2010 July 20 to July 30 • SDO – DOT – HINODE observations: July 22-24 • Recurrent AR (5 passages on the solar disk)

  9. SDO full-disk observations • The orphan penumbrae are visible for more than 48 hours and are larger than umbral regions • The structures fragment during their evolution • These SDO observations show that: • the eastern orphan penumbra is formed as the main sunspots lose part of their penumbrae • the western orphan penumbra is forming independently • In both the structures the SDO movie indicates several episodes of flux emergence • Peculiar motions are found in the orphan penumbrae: • upflows in their central regions

  10. DOT observations Note the sequenceofbrightgranules at the borderof the orphanpenumbra Note the chromosphericfilamentarystructureabove the orphanpenumbra In the chromospherewefindupflows in the central part of the structure

  11. HINODE/SP observations “uncombed” structure!!! Maps of physical parameters from the standard M-E Hinode CSAC inversions (level 1.5 data) Azimuth ambiguity was solved using the Non-Potential Field Calculation (Georgoulis, 2005) Line-of-sight (LOS) velocities were calibrated assuming plasma at rest in umbrae Raster scans aligned through cross-correlation algorithms Asymmetryin Stokesprofiles

  12. HINODE/SP evolution Dark blue/bluecontours (upflow): -3/-1.5 km s-1 Red/light redcontours (downflow): +3/+1.5 km s-1 Red contours: PolarityInversionLines (PILs)

  13. HINODE/SP evolution • Peculiar plasma flows are found in the western orphan penumbra: a central upwardmotion and downflows at the edges, max values -4 / +6 km s-1 • Flows last for ≈ 8 hours and decrease in time • The upflowing region seems to fragment the penumbra • Downflows are observed until the end of Hinode observations • Evershedflows in the orphanpenumbrafilaments? • Thisstructureliesabove a PIL, with a maximumhorizontalfieldof≈ 1500 G decreasing in time • Magneticfieldlines show a “directconfiguration”, with a veryhomogeneousazimuth angle

  14. NOAA 11391 • Visible from 2012 January 3 to January 13 • SDO – HINODE observations: January 10-12 • Decaying AR (2 passages on the solar disk)

  15. G band: photosphericevolution

  16. HINODE/SP parameters

  17. Ca II H: chromosphericevolution • Lim et al. (2013) found a magnetic canopy over the filaments and an Hαbrightening at oneof the edgeof the structure • Indirect confirmation of the presence of the magnetic canopy • interaction between the positive patch of the emerging bipole and the plage negative field • presence of a strong Ca II H brighteninglikely due to magnetic reconnection between these two flux systems

  18. HINODE results • The penumbral filaments form after the emergence of an ephemeral region, that gives rise to two pores • The emergence zone has upflows of ≈ 1 km s-1 and an averagehorizontalfieldof≈ 650 G • The penumbralfilamentsformafterabout 2 hours and slightlymoveeastwardswithrespectto the AR • The regionhasanaveragefieldof≈ 1000 G and liesabove a S-shapedPIL, whereline-of-sightmotionsofabout±2 km s-1 occur (inversion and Doppler) • No evidenceof a fluxropeabove the structure • Interactionwithanoverlyingcanopy

  19. Summary • NOAA 11089 shows the presenceoflargeareas– 23" x 5" – coveredbyorphanpenumbraethathave a lifetime of days and fragment during their evolution • The magneticfieldlineshavedifferentinclinationsalong the lineofsight,indicatinganuncombedstructure • The orphanpenumbrae show upflows in the central part and downflows at the edges, lastingforhours and decreasing in time • The magneticfieldvectorhas a strong horizontalcomponent in the western orphanpenumbra, thatliesabove a PIL • NOAA 11391 show the presenceofpenumbral-likefilamentsnear the leadingsunspotabove a PIL • Abovethesestructuresmagneticreconnectionwith the overlyingcanopyfieldsoccurs at low chromosphericlevels

  20. Formationmechanism photospheric manifestation of a flux rope trapped in the photosphere (Kuckein et al., 2012a,b) the result of an emerging Ω-loop trapped in the photosphere by overlying canopy fields (Lim et al., 2013) the effect of submerging horizontal field in flattened Ω-loops (Jurčak et al., 2014) • The combination of the horizontal fields of emerging Ω-loops and an overlying canopycan give rise to the observed structures

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