Dark cores in sunspot penumbral filaments

Scharmer, G.; Gudiksen, B. V.; Kiselman, Dan; Löfdahl, Mats G.; Voort, L. H. M. Rouppe van der

doi:10.1038/nature01173

Cited by 209 publications

(248 citation statements)

References 11 publications

Supporting

Mentioning

225

Contrasting

Order By: Relevance

“…However, recent advances in adaptive optics, image selection and reconstruction at ground-based telescopes, and the advent of high-resolution space observations with Hinode (see Figure 1), have all led to a wealth of detailed information about the fine structure of sunspot umbrae and penumbrae (see e.g. Scharmer et al, 2002;Thomas and Weiss, 2008). On the other hand, the subsurface structure of sunspots is still poorly understood.…”

Section: Why Sunspots Are Interestingmentioning

confidence: 99%

See 1 more Smart Citation

Modeling the Subsurface Structure of Sunspots

et al. 2010

View full text Add to dashboard Cite

While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this article, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out a helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by Gizon et al. (2009aGizon et al. ( , 2009b. We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat.

show abstract

Section: Why Sunspots Are Interestingmentioning

confidence: 99%

“…• Observed velocities of the flow typically exceed 6 km s −1 (Rouppe van der Voort, 2002;Bellot Rubio et al, 2003a) in the outer penumbra, but can also exceed 10 km s −1 in localized patches (e.g. Bellot Rubio, Balthasar, and Collados, 2004).…”

Section: Evershed Flowmentioning

confidence: 99%

Modeling the Subsurface Structure of Sunspots

et al. 2010

View full text Add to dashboard Cite

show abstract

“…In solar physics we have witnessed interesting observational discoveries thanks to the development of novel polarimeters like the ASP, ZIMPOL or TIP. However, in order to open a true empirical window on the magnetism of the extended solar atmosphere, we need urgently an UV polarimeter in a space telescope and a cleverly-designed large ground-based solar telescope optimized for spectropolarimetric observations, and installed on an excellent site like that chosen by Scharmer et al (2002) for the Swedish l-m Solar Telescope.…”

Section: Discussionmentioning

confidence: 99%

Astrophysical Spectropolarimetry and Magnetic Field Diagnostics

Bueno

2003

Symp. - Int. Astron. Union

View full text Add to dashboard Cite

Abstract.This paper highlights the increasing interest of astrophysical spectropolarimetry by showing how remote sensing techniques based on the Hanle and Zeeman effects are allowing us to investigate the magnetism of the extended solar atmosphere. Particular emphasis is given to the development of new diagnostic windows on the weakest magnetic fields of the photosphere, chromosphere and corona. Spectropolarimetry in the He I 10830 A multiplet is allowing us to infer the three-dimensional geometry of the magnetic fields that confine the plasma of solar prominences. Multilevel modelling of the Hanle and Zeeman effects in the Ca II IR triplet and other chromospheric lines is helping us to decipher the strength and topology of chromospheric magnetic fields in regions where photospheric magnetograms show the well-known 'salt and pepper' patterns of mixed polarities. The Hanle effect in molecular lines, as well as in atomic lines of rare-earth elements like Ce II, offers a novel diagnostic tool for empirical investigations of 'turbulent' magnetic fields in relatively deep regions of the 'quiet' solar photosphere.

show abstract

“…Figure 1 shows a high-resolution SST image of part of a large sunspot (Scharmer 2002). The dark umbral region of the spot is clearly visible in the lower part of this image.…”

Section: Sunspotsmentioning

confidence: 99%

Magnetic fields in the solar photosphere

Bushby

2008

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

Recent high-resolution observations of the surface of the Sun have revealed the fine structure of a vast array of complex photospheric magnetic features. Observations of these magnetic field structures have already greatly enhanced our theoretical understanding of the interactions between magnetic fields and turbulent convection, and future photospheric observations will inevitably present new theoretical challenges. In this review, I discuss recent progress that has been made in the modelling of photospheric magnetic fields. In particular, I focus upon the complex field structures that are observed within the umbrae and the penumbrae of sunspots. On a much smaller scale, I also discuss models of the highly localized magnetic field structures that are observed in less magnetically active regions of the photosphere. As the spatial resolution of telescopes has improved over the last few years, it has now become possible to observe these features in detail, and theoretical models can now describe much of this behaviour. In the last section of this review, I discuss some of the remaining unanswered questions.

show abstract

Dark cores in sunspot penumbral filaments

Cited by 209 publications

References 11 publications

Modeling the Subsurface Structure of Sunspots

Modeling the Subsurface Structure of Sunspots

Astrophysical Spectropolarimetry and Magnetic Field Diagnostics

Magnetic fields in the solar photosphere

Contact Info

Product

Resources

About