Evolutionary tracks of magnetic bright points as seen by IMaX/Sunrise Utz Dominik Work performed in the frame of FWF project: Spektroskopische und statistische.

Evolutionary tracks of magnetic bright points as seen by IMaX/Sunrise

Utz Dominik

Work performed in the frame of FWF project:Spektroskopische und statistische

Untersuchungen an MBPs (FWF J3176)

18.04.23 1Utz Dominik IV Reunión Española

de Física Solar y Heliosférica

D. Utz1,2, J. C. del Toro Iniesta1, L. R. Bellot Rubio1, J. Jurčák3

Instituto de Astrofísica de Andalucía, CSIC, Granada, Spain1

IGAM, Institut of Physics, University of Graz, Austria2

Ondrejov Observatory, Czech Academy of Sciences3

Contents of the Talk• Motivation

– Background about MBPs– The Creation & Dissolution of MBPs

• Sunrise/IMaX data– Mission and Data– Adaption of the Algorithm– Tracking of features

• Results– Evolutionary Tracks– Statistical Results

18.04.23Utz Dominik IV Reunión Española

de Física Solar y Heliosférica 2

http://www.mps.mpg.de/images/projekte/sunrise/sunrise_xl.jpg

Magnetic Bright Points

• Small scale magnetic flux concentrations– kG fields– ~ 200 km diameters– Bright (especially in the G-band)– Found in intergranular regions– Lifetimes in min. range

• Theoretical Models– Single isolated flux tubes

• In the higher atmosphere canopy structue– Created by convective collapse process



Creation & Dissolution



Phase I: Creation:-> by convective collapse?

Phase II: stabile evolution; stabilisation by: ?

Phase III: Dissolution; by ?

Sunrise/IMaX• Launched June the 8th 2009• 1 m Gregorian telescope flown

in the stratosphere about 30 km• Consists of SuFi & IMaX• Adaption works and preparation

for a second flight under way

Imaging Magnetograph eXperiment:Fe line tripplet at 5250.2 Ådifferent operation modes with 2, 4, 11+ cont. wavelength point sampling50 by 50 arcsec2 FOV (0.055 ´´/pixel)



Image examples



Fig.: shows from left to right, top to bottom (color coded inversions):

• IMaX, intensity continuum image (taken 227 mÅ off the line centre)

• IMaX intensity blue flank image (-40 mÅ) used for tracking

• IMaX total absolute circular polarisation

• Magnetic field strength map• Magnetic field inclination map• LOS velocity map• Temperature maps

@ log(τ) = 0, -1, -2

Identified features



Two types of features:

<- wrongly identified granular features

Correctly ->identified MBPs

Difference in continuum line flank samples!

-> using blue line flank for identification

Tracking



• From the identification a set of x & y – positions

• Requirements:– Considering maximum

distance– Shortest total path– No crossings

Two possible approaches:

• Feature track assigning:• Unique solution• Singular usage

of information• Complicated

to implement

• Pointer assignment:• Easy to implement• Non time invariant• Multiple ussage of

the same point

An Example:

Evolutionary track case Iconvective collapse example

• Fig.: shows the temporal evolution of a tracked MBP in the plasma parameter maps. From top to bottom: blue line flank continuum (-40 mÅ) off the line centre, continuum intensity map, temperature map, magnetic field strength map, line of sight velocity map, magnetic field strength map; The diamond marks the MBP feature.



Fig.: illustrating primary physical Fig.: illustration of physical parameters of MBP evolution.First row (left to right):The magnetic field strength,The temperature at log τ = 0The line of sight velocityThe temperature at log τ = -1

Fig.: continuation of physicalparameters of MBP evolution.First row (left to right):The magnetic field inclination,The temperature at log τ = -2The diameter of the MBP structureThe blue line flank intensity

Evolutionary track case IIabout the importance of upflows

• Fig.: same physical parameter maps as before.Interesting are the strong upflows close by to the strong downflows!



Fig.: illustration of physical parameters of MBP evolution.First row (left to right):The magnetic field strength,The temperature at log τ = 0The line of sight velocityThe temperature at log τ = -1


Look how correlated the downflow with this upflow is!

Evolutionary track case IIIno strong flows & nevertheless

magnetic field amplification

• Fig.: shows the plasma paraemters. There is no strong down/upflow at the time of magnetic field amplification. The obvious difference is we have already an extended patch of strong magnetic field.





Evolutionary track case IVa general (complex to interprete) case

• Fig.: as before the plasma parameter map for a feature nicely situated in between granules.





Statistics

• Fig.: shows the magnetic field strength of the measured MBP tracks (sorted for increasing initial magnetic field strengths). The error bars give the maximum and final magnetic field strength during the track.



Fig.: Upper panel: the LOS velocity component (sorted as before). The maximum and final measurements are given by the error bars.Lower panel: The magnetic field inclination angles (sorted in the same manner). The error bar gives again the maximum and final inclination.

Statistics II



Fig.: depicts the magnetic field strength distributions of: the maximum MBP field strengths (dark red), the initial magnetic field strengths (yellow), the dissolution field strength (black color), the complete FOV and of all MBP measurements, the later both normalised to the number of tracks (dashed orange and dashed brown). The right side gives the same plot as on the left but with logarithmic x-axis. The 3 dash-dotted vertical lines illustrate: the mean field strength (130 G), the mean plus 2 times the RMS value (300 G) and the equipartition field strength (420 G).

Conclusions I

• Evolutionary tracks:– The convective collapse model is probably only one process leading to

field amplification and is in reality much more complicated– Importance of close by strong transient upflows (2nd mechanism)?– For extended strong magnetic field patches (3rd mechanism)?– Mechanism working with time delays (4th mechanism)?– In general complicated to interprete– No clear answers about the stabilisation and dissolution phase



Where are we now? Even in deeper trouble as the starting point of the evolution seems to be not fixed anymore. Convecitve Collapse with QUESTION MARK!

Conclusions II

• Statistical part:– MBPs start out of a patch of equipartition strong magnetic field– Most don’t reach the kG region with mean amplification factors of 2 to 3– Dissolution when the magnetic field drops down to mean magnetic fields

plus 2 times the standard deviation– Mostly not too strong downflows but in general all the time downflows– Nearly no flow reversals– Magnetic field gets more inclined during the life (weaker inclinations in

the beginning and in the end)– MBPs with stronger starting fields start more inclined (vertical)



Discussion & Summary



Fig.: There are definitely more worthwhile features to be studied (like aliens on the Sun).If you are interested in the topic, more details can be found (about the talk not the alien):Utz, D. et al. ApJ, 2013, under preparation: Magnetic bright point evolutionary tracks observed by IMaX/Sunrise

Evolutionary tracks of magnetic bright points as seen by IMaX/Sunrise Utz Dominik Work performed in the frame of FWF project: Spektroskopische und statistische.

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