Formation of Solar Magnetic Flux Tubes with Kilogauss Field Strength Induced by Convective Instability

Nagata, Shinji; Tsuneta, S.; Suematsu, Y.; Ichimoto, Kiyoshi; Katsukawa, Y.; Shimizu, Toshifumi; Yokoyama, T.; Tarbell, T. D.; Lites, B. W.; Shine, R. A.; Berger, Thomas; Title, A. M.; Rubio, L. R. Bellot; Suárez, D. Orozco

doi:10.1086/588026

Cited by 99 publications

(119 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Magnetic bipoles and, more generally, magnetic regions emerge from the solar interior on a wide range of length-and timescales, stretching from those of the largest activity complexes, with horizontal sizes comparable to the depth of the entire convection zone, through those of intermediate-sized active regions and ephemeral regions down to small-scale, granule-sized emergence events (as recently observed with Hinode/SOT by Centeno et al 2007;Otsuji et al 2007;Ishikawa et al 2008;Orozco Suárez et al 2008;Martinez Gonzalez & Bellot Rubio 2009). Observationally, the use of Stokes polarimetry and the achievement of subarcsecond resolution in both ground-based and space observations have provided a wealth of knowledge concerning the emergence of magnetic field on different scales and at individual heights (additionally to the references just mentioned, see the papers by Martinez Pillet et al 1994;Lites et al 1995Lites et al , 1998De Pontieu 2002;Kubo et al 2003;Harvey et al 2007;Lites 2009;Nagata et al 2008;Okamoto et al 2008;Shimizu et al 2008;van Driel-Gesztelyi & Culhane 2009). Yet, when rising, the magnetized plasma straddles the extremely inhomogeneous region constituted by the photosphere, chromosphere, and transition region, where density and pressure change by more than eight orders of magnitude in only a few Mm in height and temperature goes from photospheric values up to a million K in the corona.…”

Section: Introductionmentioning

confidence: 87%

“…Observationally, Bellot Rubio et al (2001) and SocasNavarro & Manso Sainz (2005) found indirect evidence of this process. Direct observational signatures of convective collapse were found by Nagata et al (2008) from Hinode data. Cheung et al (2008) study an instance of convective collapse in their flux emergence simulation, considering, in particular, the field strength and brightness of the resulting element compared with the surroundings as one would observe it and the small Wilson depression that develops within the collapsed magnetic element.…”

Section: Lagrangian Evolution In the Photospherementioning

confidence: 99%

See 1 more Smart Citation

Magnetic flux emergence into the solar photosphere and chromosphere

Tortosa-Andreu¹,

Moreno‐Insertis

2009

A&A

View full text Add to dashboard Cite

Aims. We model the emergence of magnetized plasma across granular convection cells and the low atmosphere, including layers up to the mid-chromosphere. Methods. Three-dimensional numerical experiments are carried out in which the equations of MHD and radiative transfer are solved self-consistently. We use the MURaM code, which assumes local thermodynamic equilibrium between plasma and radiation. Results. In the photosphere, we find good agreement between our simulation predictions and observational results obtained with the Hinode satellite for the velocity and magnetic fields. We also confirm earlier simulation results by other authors. Our experiments reveal a natural mechanism of formation of twisted magnetic flux tubes that results from the retraction of photospheric horizontal fields at new intergranular lanes in decaying granules. In the chromosphere, we present evidence for the non-radiative heating of the emerging magnetized plasma due to the passage of shocks and/or ohmic dissipation. We study the formation of high-temperature points in the magnetic domain. We detect two types of points, classified according to whether they have a photospheric counterpart or otherwise. We also find evidence of those two types in Hinode observations. Using Lagrangian tracing of a large statistical sample of fluid particles, we detect and study episodes of convective collapse of magnetic elements returning to the photosphere. On the other hand, we study the maximum heights reached by all tracers, magnetized or otherwise. Only a small fraction (1.3%) of the magnetic elements reach the mid-chromosphere (z > 750 km), while virtually no unmagnetized elements in the sample rise above the level of the reverse granulation (a few 100 km above the photosphere). We find that the rise into the chromosphere occurs in the form of successive jumps with intermediate stops rather than in a smooth continuous fashion and propose a tentative explanation of this behavior. Finally, also using Lagrange tracing, we document the creation of hightemperature points in the chromosphere via rising shock fronts.

show abstract

Section: Introductionmentioning

confidence: 87%

Section: Lagrangian Evolution In the Photospherementioning

confidence: 99%

Magnetic flux emergence into the solar photosphere and chromosphere

Tortosa-Andreu¹,

Moreno‐Insertis

2009

A&A

View full text Add to dashboard Cite

show abstract

“…One is a combination of convective collapse processes and their associated downflows together with occasional rebounded material propagating upwards (see SocasNavarro & Manso Sainz 2005;or Nagata et al 2008). The other mechanism is siphon flows along magnetic arches (Montesinos & Thomas 1993).…”

Section: Discussionmentioning

confidence: 99%

“…Shimizu et al (2008b) found strong (supersonic) downflows, in, both, the vicinity of sunspots and in the quiet Sun. These downflows were interpreted as representing the formation of a strong field concentration through the process of convective collapse (see also Nagata et al 2008;and Fischer et al 2009). One of the few other cases where the origin of these profiles has been associated with a physical scenario was presented by Socas-Navarro & Manso Sainz (2005).…”

Section: Introductionmentioning

confidence: 99%

Ubiquitous quiet-Sun jets

Pillet

Iniesta

Noda

2011

A&A

View full text Add to dashboard Cite

Context. IMaX/Sunrise has recently reported the temporal evolution of highly dynamic and strongly Doppler shifted Stokes V signals in the quiet Sun. Aims. We attempt to identify the same quiet-Sun jets in the Hinode spectropolarimeter (SP) data set. Methods. We generate combinations of linear polarization magnetograms with blue-and redshifted far-wing circular polarization magnetograms to allow an easy identification of the quiet-Sun jets.Results. The jets are identified in the Hinode data where both red-and blueshifted cases are often found in pairs. They appear next to regions of transverse fields that exhibit quiet-Sun neutral lines. They also have a clear tendency to occur in the outer boundary of the granules. These regions always display highly displaced and anomalous Stokes V profiles. Conclusions. The quiet Sun is pervaded with jets formed when new field regions emerge at granular scales loaded with horizontal field lines that interact with their surroundings. This interaction is suggestive of some form of reconnection of the involved field lines that generates the observed high speed flows.

show abstract

“…The origin of Stokes V profiles featuring both properties still remains under debate. A&A 569, A73 (2014) Bellot Rubio et al (2001), Shimizu et al (2008), Nagata et al (2008) and Fischer et al (2009) concluded that the cause of the strong red-shifted signals they found is convective collapse inside a magnetic flux tube. This process, which was first proposed on theoretical grounds by Parker (1978), Webb & Roberts (1978), and Spruit (1979), makes the plasma inside a magnetic flux tube unstable, cool down, and fall along the field lines, sometimes at supersonic speeds.…”

Section: Introductionmentioning

confidence: 98%

High speed magnetized flows in the quiet Sun

Noda

Borrero

Suárez

et al. 2014

A&A

View full text Add to dashboard Cite

Context. We analyzed spectropolarimetric data recorded with Hinode/SP in quiet-Sun regions located at the disk center. We found single-lobed Stokes V profiles showing highly blue-and red-shifted signals. Oftentimes both types of events appear to be related to each other. Aims. We aim to set constraints on the nature and physical causes of these highly Doppler-shifted signals, as well as to study their spatial distribution, spectropolarimetric properties, size, and rate of occurrence. Also, we plan to retrieve the variation of the physical parameters with optical depth through the photosphere. Methods. We have examined the spatial and polarimetric properties of these events using a variety of data from the Hinode spacecraft. We have also inferred the atmospheric stratification of the physical parameters by means of the inversion of the observed Stokes profiles employing the Stokes Inversion based on Response functions (SIR) code. Finally, we analyzed their evolution using a time series from the same instrument. Results. Blue-shifted events tend to appear over bright regions at the edge of granules, while red-shifted events are seen predominantly over dark regions on intergranular lanes. Large linear polarization signals can be seen in the region that connects them. The magnetic structure inferred from the time series revealed that the structure corresponds to a Ω-loop, with one footpoint always over the edge of a granule and the other inside an intergranular lane. The physical parameters obtained from the inversions of the observed Stokes profiles in both events show an increase with respect to the Harvard-Smithonian reference atmosphere in the temperature at log τ 500 ∈ (−1, −3) and a strong magnetic field, B ≥ 1 kG, at the bottom of the atmosphere that quickly decreases upward until vanishing at log τ 500 ≈ −2. In the blue-shifted events, the LOS velocities change from upflows at the bottom to downflows at the top of the atmosphere. Redshifted events display the opposite velocity stratification. The change of sign in LOS velocity happens at the same optical depth in which the magnetic field becomes zero. Conclusions. The physical mechanism that best explains the inferred magnetic field configuration and flow motions is a siphon flow along an arched magnetic flux tube. Further investigation is required, however, as the expected features of a siphon flow cannot be unequivocally identified.

show abstract

Formation of Solar Magnetic Flux Tubes with Kilogauss Field Strength Induced by Convective Instability

Cited by 99 publications

References 18 publications

Magnetic flux emergence into the solar photosphere and chromosphere

Magnetic flux emergence into the solar photosphere and chromosphere

Ubiquitous quiet-Sun jets

High speed magnetized flows in the quiet Sun

Contact Info

Product

Resources

About