Flow patterns around old sunspots and flare activity

New magnetic flux emerges significantly more probably in already existing solar active regions. Based on the the Debrecen Observatory photographic observations, several active regions are collected, where at least one large, X-class flare was recorded, and emergence of new activity, birth and quick motion of new umbrae was observed in the vicinity of old spots, the new activity emerged in the center of the old active region. Newly emerging magnetic flux in older sunspot groups can be distinguished by its quicker and generally westward proper motions. Umbrae of the new activity do not coalesce with older umbrae of the same polarity, but both elastic and inelastic collisions between them can be observed. Spots of the emerging new activity can flow around old unipolar spots (presumably shallower structures, “ω-loops”) westward, like a hydrodynamic flow around a cylinder, forming a wake behind it. Collision of different polarities in the wake can lead to large flares. The presence of old spots disturbs the normal emergence of the new activity, so motions of the new spots are distorted by the flow, the new emerging “Ω-loop” can be stuck between the umbrae of the old, tight dipole, the orientation of the new dipole can be distorted by as much as 180◦. The general direction of the flow around the old spots seems to depend on the latitude, the angle between the motion axis and the E-W direction grows with the latitude. The intensive flare activity seems to be connected strongly with the newly emerging magnetic flux; interacting of differently oriented dipoles and the difference of the orientation of the emerging new dipole from the ordinary Hale-Nicholson orientation is also significant. Simply large gradients of magnetic fields (δ-configuration) are not enough, dynamical processes (emergence of new flux, shearing or colliding motions of umbrae of different magnetic polarity) must also be present for large flares

Fotoszférikus horizontális áramlások vizsgálata = Study of photospheric horizontal flows

Debreceni fotohéliogramok, TRACE fotoszféra-, kromoszféra- és koronaképek valamint SOHO MDI magnetogramok alapján a NOAA 9373 sz. szoláris aktiv vidék fejlődését vizsgáltuk 2001. márc. 10-21. közt. Megállapítható volt, hogy az egyszerű bipoláris foltcsoportnak látszó aktív vidék a valóságban legalább 7 bipoláris napfoltcsoportot tartalmaz. Vezető foltja a követő résztől elszakadva kb. két fokot mozgott héliografikus szélességben, ami nagyon szokatlan. Új mágneses fluxus közel egyidejűleg bukkan fel az aktív vidék két átellenes oldalán, ami úgy értelmezhető, hogy a régi, a konvektív zóna tetején úszó mágneses struktúra akadályozza a felbukkanást. A régi és az új mágneses struktúrák közt, a TRACE koronaképek alapján, nincs kölcsönhatás, ez magyarázza az egyébként bonyolult és gyorsan változó napfoltcsoport csekély aktivitását. A megfigyelt fejlődés megfelel annak a modellnek, amely szerint az aktív vidékek a konvektív zóna alatti rétegben (ahol a dinamó-mechanizmus működik) bekövetkező instabilitás következtében felúszó mágneses erővonalköteg felszínre bukkanásával keletkeznek. Ez egy ideig kapcsolódik még a mélyebb rétegekhez, majd a turbulencia miatt lefűződik, a mágneses erővonalak átkötődnek a felszín alatt, így az aktív vidék egy egyre sekélyebb, a konvektív zóna tetején úszó képződmény lesz. Legutóljára a legstabilabb vezető folt marad csak, amelyet a körülötte lévő áramlás stabilizál, és a turbulencia végül a külső peremén hatva ezt is szétszórja. | Evolution of solar active region AR NOAA 9373 was studied between 10-21 March 2001, based on Debrecen photoheliograms, TRACE observations of the photosphere, chromosphere and corona, and SOHO MDI magnetograms. The AR, a seemingly simple bipolar sunspot group, in reality contained at least 7 bipolar sunspot groups. Its leader spot detached from the following part of the group, and moved about two degrees in latitude, which is unusual. New magnetic flux emerges almost simultaneously at the opposite sides of the active region, which can be interpreted as the old, shallow magnetic structure, swimming atop the convective zone, does not allow the emergence of the new flux. There is no interaction between the old and new magnetic structures, according to the TRACE coronal images, this can cause the low activity of the complex and quickly changing AR. The evolution may be described as active regions appear due to instability in the layer immediately below the convective zone (where the dynamo-mechanism operates), the magnetic flux-ropes became buoyant and emerge to the surface. They are connected to the deeper layers for some time, then the connection breaks up due to turbulence and the magnetic lines of force reconnect below the surface, so the region becomes a gradually shallower structure swimming atop the convective zone. Finally only the most stable leader spot remains, stabilized with a ring flow around it, and further becomes dispersed by turbulence acting at its periphery

Doppler and proper motions accompanying formation of an additional magnetic flux in the mature solar active region (NOAA 7216)

We document the evolution of an additional magnetic flux in the photosphere of a fully developed sunspot group, we measure longitudinal magnetic field, line-of-sight motions, and proper motions of sunspots in the group during this process. We demonstrate the close correlation of magnetic field, Doppler and proper motion singularities with the area in which additional magnetic flux appears and the new penumbrae and umbrae develop. We discuss the probable reasons for this fact and for the region's weak flare activity. There exist in the group about eight sunspots with the Evershed effect, differing in form, in dependence on the history of development of the spot in which it is observed