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THE FORMATION AND DISINTEGRATION OF MAGNETIC BRIGHT POINTS OBSERVED BY<i>SUNRISE</i>/IMaX
Utz, D.,del Toro Iniesta, J. C.,Bellot Rubio, L. R.,Jurč,á,k, J.,Martí,nez Pillet, V.,Solanki, S. K.,Schmidt, W. IOP Publishing 2014 The Astrophysical journal Vol.796 No.2
<P>The evolution of the physical parameters of magnetic bright points (MBPs) located in the quiet Sun (mainly in the interwork) during their lifetime is studied. First, we concentrate on the detailed description of the magnetic field evolution of three MBPs. This reveals that individual features follow different, generally complex, and rather dynamic scenarios of evolution. Next, we apply statistical methods on roughly 200 observed MBP evolutionary tracks. MBPs are found to be formed by the strengthening of an equipartition field patch, which initially exhibits a moderate downflow. During the evolution, strong downdrafts with an average velocity of 2.4 km s(-1) set in. These flows, taken together with the concurrent strengthening of the field, suggest that we are witnessing the occurrence of convective collapses in these features, although only 30% of them reach kG field strengths. This fraction might turn out to be larger when the new 4mclass solar telescopes are operational as observations of MBPs with current state of the art instrumentation could still be suffering from resolution limitations. Finally, when the bright point disappears (although the magnetic field often continues to exist) the magnetic field strength has dropped to the equipartition level and is generally somewhat weaker than at the beginning of the MBP's evolution. Also, only relatively weak downflows are found on average at this stage of the evolution. Only 16% of the features display upflows at the time that the field weakens, or the MBP disappears. This speaks either for a very fast evolving dynamic process at the end of the lifetime, which could not be temporally resolved, or against strong upflows as the cause of the weakening of the field of these magnetic elements, as has been proposed based on simulation results. It is noteworthy that in about 10% of the cases, we observe in the vicinity of the downflows small-scale strong (exceeding 2 km s-1) intergranular upflows related spatially and temporally to these downflows. The paper is complemented by a detailed discussion of aspects regarding the applied methods, the complementary literature, and in depth analysis of parameters like magnetic field strength and velocity distributions. An important difference to magnetic elements and associated bright structures in active region plage is that most of the quiet Sun bright points display significant downflows over a large fraction of their lifetime (i.e., in more than 46% of time instances/measurements they show downflows exceeding 1 km s(-1)).</P>
Convectively Driven Sinks and Magnetic Fields in the Quiet-Sun
Requerey, Iker S.,Del Toro Iniesta, Jose Carlos,Rubio, Luis R. Bellot,Pillet, Valentí,n Martí,nez,Solanki, Sami K.,Schmidt, Wolfgang American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.229 No.1
<P>We study the relation between mesogranular flows, convectively driven sinks and magnetic fields using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board SUNRISE. We obtain the horizontal velocity flow fields of two quiet-Sun regions (31.2 x 31.2 Mm(2)) via local correlation tracking. Mesogranular lanes and the central position of sinks are identified using Lagrange tracers. We find 6.7 x 10(-2) sinks per Mm(2) in the two observed regions. The sinks are located at the mesogranular vertices and turn out to be associated with (1) horizontal velocity flows converging to a central point and (2) long-lived downdrafts. The spatial distribution of magnetic fields in the quiet-Sun is also examined. The strongest magnetic fields are preferentially located at sinks. We find that 40% of the pixels with longitudinal components of the magnetic field stronger than 500 G are located in the close neighborhood of sinks. In contrast, the small-scale magnetic loops detected by Martinez Gonzalez et al. in the same two observed areas do not show any preferential distribution at mesogranular scales. The study of individual examples reveals that sinks can play an important role in the evolution of quiet-Sun magnetic features.</P>
A Tale of Two Emergences: Sunrise II Observations of Emergence Sites in a Solar Active Region
Centeno, R.,Rodrí,guez, J. Blanco,Del Toro Iniesta, J. C.,Solanki, S. K.,Barthol, P.,Gandorfer, A.,Gizon, L.,Hirzberger, J.,Riethmü,ller, T. L.,Noort, M. van,Suá,rez, D. Orozco,Berkefe American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.229 No.1
<P>In 2013 June, the two scientific instruments on. board the second SUNRISE mission witnessed, in detail, a small-scale magnetic flux emergence event as part of the birth of an active region. The Imaging Magnetograph Experiment (IMaX) recorded two small (similar to 5 '') emerging flux patches in the polarized filtergrams of a photospheric Fe I spectral line. Meanwhile, the SUNRISE Filter Imager (SuFI) captured the highly dynamic chromospheric response to the magnetic fields pushing their way through the lower solar atmosphere. The serendipitous capture of this event offers a closer look at the inner workings of active region emergence sites. In particular, it reveals in meticulous detail how the rising magnetic fields interact with the granulation as they push through the Sun's surface, dragging photospheric plasma in their upward travel. The plasma that is burdening the rising field slides along the field lines, creating fast downflowing channels at the footpoints. The weight of this material anchors this field to the surface at semi-regular spatial intervals, shaping it in an undulatory fashion. Finally, magnetic reconnection enables the field to release itself from its photospheric anchors, allowing it to continue its voyage up to higher layers. This process releases energy that lights up the arch-filament systems and heats the surrounding chromosphere.</P>
Spectropolarimetric Evidence for a Siphon Flow along an Emerging Magnetic Flux Tube
Requerey, Iker S.,Cobo, B. Ruiz,Iniesta, J. C. Del Toro,Suá,rez, D. Orozco,Rodrí,guez, J. Blanco,Solanki, S. K.,Barthol, P.,Gandorfer, A.,Gizon, L.,Hirzberger, J.,Riethmü,ller, T. L.,N American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.229 No.1
<P>We study the dynamics and topology of an emerging magnetic flux concentration using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board the SUNRISE balloon-borne solar observatory. We obtain the full vector magnetic field and the line of sight (LOS) velocity through inversions of the Fe I line at 525.02 nm with the SPINOR code. The derived vector magnetic field is used to trace magnetic field lines. Two magnetic flux concentrations with different polarities and LOS velocities are found to be connected by a group of arch-shaped magnetic field lines. The positive polarity footpoint is weaker (1100 G) and displays an upflow, while the negative polarity footpoint is stronger (2200 G) and shows a downflow. This configuration is naturally interpreted as a siphon flow along an arched magnetic flux tube.</P>
Guglielmino, S. L.,Martí,nez Pillet, V.,Bonet, J. A.,del Toro Iniesta, J. Carlos,Bellot Rubio, L. R.,Solanki, S. K.,Schmidt, W.,Gandorfer, A.,Barthol, P.,Knö,lker, M. IOP Publishing 2012 The Astrophysical journal Vol.745 No.2
<P>We report on the photospheric evolution of an intermediate-scale (approximate to 4 Mm footpoint separation) magnetic bipole, from emergence to decay, observed in the quiet Sun at high spatial (0 ''.3) and temporal (33 s) resolution. The observations were acquired by the Imaging Magnetograph Experiment imaging magnetograph during the first science flight of the Sunrise balloon-borne solar observatory. The bipole flux content is 6x10(17) Mx, representing a structure bridging the gap between granular scale bipoles and the smaller ephemeral regions. Footpoints separate at a speed of 3.5 km s(-1) and reach a maximum distance of 4.5 Mm before the field dissolves. The evolution of the bipole is revealed to be very dynamic: we found a proper motion of the bipole axis and detected a change of the azimuth angle of 90 degrees in 300 s, which may indicate the presence of some writhe in the emerging structure. The overall morphology and behavior are in agreement with previous analyses of bipolar structures emerging at the granular scale, but we also found several similarities with emerging flux structures at larger scales. The flux growth rate is 2.6 x 10(15) Mx s(-1), while the mean decay rate is one order of magnitude smaller. We describe in some detail the decay phase of the bipole footpoints that includes break up into smaller structures, and interaction with preexisting fields leading to cancellation, but it appears to be dominated by an as-yet unidentified diffusive process that removes most of the flux with an exponential flux decay curve. The diffusion constant (8 x 10(2) km(2) s(-1)) associated with this decay is similar to the values used to describe the large-scale diffusion in flux transport models.</P>
SUPERSONIC MAGNETIC UPFLOWS IN GRANULAR CELLS OBSERVED WITH SUNRISE/IMAX
Borrero, J. M.,Martí,nez-Pillet, V.,Schlichenmaier, R.,Solanki, S. K.,Bonet, J. A.,del Toro Iniesta, J. C.,Schmidt, W.,Barthol, P.,Gandorfer, A.,Domingo, V.,Knö,lker, M. IOP Publishing 2010 ASTROPHYSICAL JOURNAL LETTERS - Vol.723 No.2
Morphological Properties of Slender Ca ${\rm{II}}$ H Fibrils Observed by Sunrise II
Gafeira, R.,Lagg, A.,Solanki, S. K.,Jafarzadeh, S.,Noort, M. van,Barthol, P.,Rodrí,guez, J. Blanco,Iniesta, J. C. del Toro,Gandorfer, A.,Gizon, L.,Hirzberger, J.,Knö,lker, M.,Suá,rez, American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.229 No.1
<P>We use seeing-free high spatial resolution Ca II H data obtained by the SUNRISE observatory to determine properties of slender fibrils in the lower solar chromosphere. In this work we use intensity images taken with the SUFI instrument in the Ca II H line during the second scientific flight of the SUNRISE observatory to identify and track elongated bright structures. After identification, we analyze theses structures to extract their morphological properties. We identify 598 slender Ca II H fibrils (SCFs) with an average width of around 180 km, length between 500 and 4000 km, average lifetime of approximate to 400 s, and average curvature of 0.002 arcsec(-1). The maximum lifetime of the SCFs within our time series of 57 minutes is approximate to 2000 s. We discuss similarities and differences of the SCFs with other small-scale, chromospheric structures such as spicules of type I and II, or Ca II K fibrils.</P>
Kinematics of Magnetic Bright Features in the Solar Photosphere
Jafarzadeh, S.,Solanki, S. K.,Cameron, R. H.,Barthol, P.,Rodrí,guez, J. Blanco,Iniesta, J. C. del Toro,Gandorfer, A.,Gizon, L.,Hirzberger, J.,Knö,lker, M.,Pillet, V. Martí,nez,Su&aacut American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.229 No.1
<P>Convective flows are known as the prime means of transporting magnetic fields on the solar surface. Thus, small magnetic structures are good tracers of turbulent flows. We study the migration and dispersal of magnetic bright features (MBFs) in intergranular areas observed at high spatial resolution with SUNRISE/IMaX. We describe the flux dispersal of individual MBFs as a diffusion process whose parameters are computed for various areas in the quiet-Sun and the vicinity of active regions from seeing-free data. We find that magnetic concentrations are best described as random walkers close to network areas (diffusion index, gamma = 1.0), travelers with constant speeds over a supergranule (gamma = 1.9-2.0), and decelerating movers in the vicinity of flux emergence and/or within active regions (gamma = 1.4-1.5). The three types of regions host MBFs with mean diffusion coefficients of 130 km(2) s(-1), 80-90 km(2) s(-1), and 25-70 km(2) s(-1), respectively. The MBFs in these three types of regions are found to display a distinct kinematic behavior at a confidence level in excess of 95%.</P>