Author name code: takasao ADS astronomy entries on 2022-09-14 author:"Takasao, Shinsuke" ------------------------------------------------------------------------ Title: Anatomy of Photoevaporation Base: Linking the Property of the Launched Wind to Irradiation Flux Authors: Nakatani, Riouhei; Takasao, Shinsuke Bibcode: 2022ApJ...930..124N Altcode: Ultraviolet and X-rays from radiation sources disperse nearby gas clumps by driving winds due to heating associated with the photochemical processes. This dispersal process, photoevaporation, constrains the lifetimes of the parental bodies of stars and planets. To understand this process in a universal picture, we develop an analytical model that describes the fundamental physics in the vicinity of the wind-launching region. The model explicitly links the density and velocity of photoevaporative winds at the launch points to the radiation flux reaching the wind-launching base, using a jump condition. The model gives a natural boundary condition for the wind-emanating points. We compare the analytical model with the results of radiation hydrodynamic simulations, where a protoplanetary disk is irradiated by the stellar extreme-ultraviolet, and confirm good agreement of the base density and velocity, and radial profiles of mass-loss rates. We expect that our analytical model is applicable to other objects subject to photoevaporation not only by extreme-ultraviolet but by far-ultraviolet/X-rays with suitable modifications. Future self-consistent numerical studies can test the applicability. Title: Probing the Physics of the Solar Atmosphere with the Multi-slit Solar Explorer (MUSE). II. Flares and Eruptions Authors: Cheung, Mark C. M.; Martínez-Sykora, Juan; Testa, Paola; De Pontieu, Bart; Chintzoglou, Georgios; Rempel, Matthias; Polito, Vanessa; Kerr, Graham S.; Reeves, Katharine K.; Fletcher, Lyndsay; Jin, Meng; Nóbrega-Siverio, Daniel; Danilovic, Sanja; Antolin, Patrick; Allred, Joel; Hansteen, Viggo; Ugarte-Urra, Ignacio; DeLuca, Edward; Longcope, Dana; Takasao, Shinsuke; DeRosa, Marc L.; Boerner, Paul; Jaeggli, Sarah; Nitta, Nariaki V.; Daw, Adrian; Carlsson, Mats; Golub, Leon; The Bibcode: 2022ApJ...926...53C Altcode: 2021arXiv210615591C Current state-of-the-art spectrographs cannot resolve the fundamental spatial (subarcseconds) and temporal (less than a few tens of seconds) scales of the coronal dynamics of solar flares and eruptive phenomena. The highest-resolution coronal data to date are based on imaging, which is blind to many of the processes that drive coronal energetics and dynamics. As shown by the Interface Region Imaging Spectrograph for the low solar atmosphere, we need high-resolution spectroscopic measurements with simultaneous imaging to understand the dominant processes. In this paper: (1) we introduce the Multi-slit Solar Explorer (MUSE), a spaceborne observatory to fill this observational gap by providing high-cadence (<20 s), subarcsecond-resolution spectroscopic rasters over an active region size of the solar transition region and corona; (2) using advanced numerical models, we demonstrate the unique diagnostic capabilities of MUSE for exploring solar coronal dynamics and for constraining and discriminating models of solar flares and eruptions; (3) we discuss the key contributions MUSE would make in addressing the science objectives of the Next Generation Solar Physics Mission (NGSPM), and how MUSE, the high-throughput Extreme Ultraviolet Solar Telescope, and the Daniel K Inouye Solar Telescope (and other ground-based observatories) can operate as a distributed implementation of the NGSPM. This is a companion paper to De Pontieu et al., which focuses on investigating coronal heating with MUSE. Title: Spontaneous Formation of Outflows Powered by Rotating Magnetized Accretion Flows in a Galactic Center Authors: Takasao, Shinsuke; Shuto, Yuri; Wada, Keiichi Bibcode: 2022ApJ...926...50T Altcode: 2021arXiv211107373T We investigate how magnetically driven outflows are powered by a rotating, weakly magnetized accretion flow onto a supermassive black hole using axisymmetric magnetohydrodynamic simulations. Our proposed model focuses on the accretion dynamics on an intermediate scale between the Schwarzschild radius and the galactic scale, which is ~1-100 pc. We demonstrate that a rotating disk formed on a parsec-scale acquires poloidal magnetic fields via accretion, and this produces an asymmetric bipolar outflow at some point. The formation of the outflow was found to follow the growth of strongly magnetized regions around disk surfaces (magnetic bubbles). The bipolar outflow grew continuously inside the expanding bubbles. We theoretically derived the growth condition of the magnetic bubbles for our model that corresponds to a necessary condition for outflow growth. We found that the north-south asymmetrical structure of the bipolar outflow originates from the complex motions excited by accreting flows around the outer edge of the disk. The bipolar outflow comprises multiple mini-outflows and downflows (failed outflows). The mini-outflows emanate from the magnetic concentrations (magnetic patches). The magnetic patches exhibit inward drifting motions, thereby making the outflows unsteady. We demonstrate that the inward drift can be modeled using a simple magnetic patch model that considers magnetic angular momentum extraction. This study could be helpful for understanding how asymmetric and nonsteady outflows with complex substructures are produced around supermassive black holes without the help of strong radiation from accretion disks or entrainment by radio jets such as molecular outflows in radio-quiet active galactic nuclei, e.g., NGC 1377. Title: Probing the Physics of the Solar Atmosphere with the Multi-slit Solar Explorer (MUSE): II. Flares and Eruptions Authors: Cheung, Chun Ming Mark; Martinez-Sykora, Juan; Testa, Paola; De Pontieu, Bart; Chintzoglou, Georgios; Rempel, Matthias; Polito, Vanessa; Kerr, Graham; Reeves, Katharine; Fletcher, Lyndsay; Jin, Meng; Nobrega, Daniel; Danilovic, Sanja; Antolin, Patrick; Allred, Joel; Hansteen, Viggo; Ugarte-Urra, Ignacio; DeLuca, Edward; Longcope, Dana; Takasao, Shinsuke; DeRosa, Marc; Boerner, Paul; Jaeggli, Sarah; Nitta, Nariaki; Daw, Adrian; Carlsson, Mats; Golub, Leon Bibcode: 2021AGUFMSH51A..08C Altcode: Current state-of-the-art spectrographs cannot resolve the fundamental spatial (sub-arcseconds) and temporal scales (less than a few tens of seconds) of the coronal dynamics of solar flares and eruptive phenomena. The highest resolution coronal data to date are based on imaging, which is blind to many of the processes that drive coronal energetics and dynamics. As shown by IRIS for the low solar atmosphere, we need high-resolution spectroscopic measurements with simultaneous imaging to understand the dominant processes. In this paper: (1) we introduce the Multi-slit Solar Explorer (MUSE), a spaceborne observatory to fill this observational gap by providing high-cadence (<20 s), sub-arcsecond resolution spectroscopic rasters over an active region size of the solar transition region and corona; (2) using advanced numerical models, we demonstrate the unique diagnostic capabilities of MUSE for exploring solar coronal dynamics, and for constraining and discriminating models of solar flares and eruptions; (3) we discuss the key contributions MUSE would make in addressing the science objectives of the Next Generation Solar Physics Mission (NGSPM), and how MUSE, the high-throughput EUV Solar Telescope (EUVST) and the Daniel K Inouye Solar Telescope (and other ground-based observatories) can operate as a distributed implementation of the NGSPM. This is a companion paper to De Pontieu et al. (2021, also submitted to SH-17), which focuses on investigating coronal heating with MUSE. Title: Modeling the corona and XUV emission from the Sun and Sun-like stars Authors: Shoda, Munehito; Takasao, Shinsuke Bibcode: 2021AGUFM.P55D1960S Altcode: The evolution of the planetary atmosphere is significantly affected by the XUV emission from the host star. It is, however, impossible to directly measure the XUV spectrum of a given star because XUV photons suffer from significant interstellar extinction. In this presentation, we propose a model to predict the XUV emission from Sun-like stars, by extending the self-consistent solar coronal heating model. The simulations are performed for a range of loop lengths and magnetic filling factors at the stellar surface. With the solar parameters, our model reproduces the observed solar XUV spectrum below the Lyman edge, which validates the capability in predicting the XUV spectra of other Sun-like stars. The model also reproduces the observed nearly-linear relation between the unsigned magnetic flux and X-ray luminosity. From the simulation runs with various loop lengths and filling factors, we have found a scaling relation of logLEUV = 9.93 + 0.67logLX where LEUV and LX are the cgs-unit luminosity in the EUV (100 A < < 912 A) and X-ray (5 A < 100 A) ranges, respectively. By assuming a power-law relation between the Rossby number and magnetic filling factor, the widely known relation between the Rossby number and X-ray luminosity is also reproduced. This study provides the theoretical relation useful in estimating the hidden stellar EUV luminosity from X-ray observations. Title: Corona and XUV emission modelling of the Sun and Sun-like stars Authors: Shoda, Munehito; Takasao, Shinsuke Bibcode: 2021A&A...656A.111S Altcode: 2021arXiv210608915S The X-ray and extreme-ultraviolet (EUV) emissions from low-mass stars significantly affect the evolution of the planetary atmosphere. However, it is observationally difficult to constrain the stellar high-energy emission because of the strong interstellar extinction of EUV photons. In this study, we simulate the XUV (X-ray plus EUV) emission from Sun-like stars by extending the solar coronal heating model that self-consistently solves, with sufficiently high resolution, the surface-to-coronal energy transport, turbulent coronal heating, and coronal thermal response by conduction and radiation. The simulations are performed with a range of loop lengths and magnetic filling factors at the stellar surface. With the solar parameters, the model reproduces the observed solar XUV spectrum below the Lyman edge, thus validating its capability of predicting the XUV spectra of other Sun-like stars. The model also reproduces the observed nearly linear relation between the unsigned magnetic flux and the X-ray luminosity. From the simulation runs with various loop lengths and filling factors, we also find a scaling relation, namely log LEUV = 9.93 + 0.67 log LX, where LEUV and LX are the luminosity in the EUV (100 Å < λ ≤ 912 Å) and X-ray (5 Å < λ ≤ 100 Å) range, respectively, in cgs. By assuming a power-law relation between the Rossby number and the magnetic filling factor, we reproduce the renowned relation between the Rossby number and the X-ray luminosity. We also propose an analytical description of the energy injected into the corona, which, in combination with the conventional Rosner-Tucker-Vaiana scaling law, semi-analytically explains the simulation results. This study refines the concepts of solar and stellar coronal heating and derives a theoretical relation for estimating the hidden stellar EUV luminosity from X-ray observations. Title: Hydrodynamic Model of Hα Emission from Accretion Shocks of a Proto-giant Planet and Circumplanetary Disk Authors: Takasao, Shinsuke; Aoyama, Yuhiko; Ikoma, Masahiro Bibcode: 2021ApJ...921...10T Altcode: 2021arXiv210616113T Recent observations have detected excess Hα emission from young stellar systems with an age of several Myr such as PDS 70. One-dimensional radiation-hydrodynamic models of shock-heated flows that we developed previously demonstrate that planetary accretion flows of >a few ten km s-1 can produce Hα emission. It is, however, a challenge to understand the accretion process of proto-giant planets from observations of such shock-originated emission because of a huge gap in scale between the circumplanetary disk (CPD) and the microscopic accretion shock. To overcome the scale gap problem, we combine two-dimensional, high-spatial-resolution global hydrodynamic simulations and the one-dimensional local radiation-hydrodynamic model of the shock-heated flow. From such combined simulations for the protoplanet-CPD system, we find that the Hα emission is mainly produced in localized areas on the protoplanetary surface. The accretion shocks above the CPD produce much weaker Hα emission (approximately one to two orders of magnitude smaller in luminosity). Nevertheless, the accretion shocks above the CPD significantly affect the accretion process onto the protoplanet. The accretion occurs at a quasi-steady rate if averaged on a 10 day timescale, but its rate shows variability on shorter timescales. The disk surface accretion layers including the CPD shocks largely fluctuate, which results in the time-variable accretion rate and Hα luminosity of the protoplanet. We also model the spectral emission profile of the Hα line and find that the line profile is less time-variable despite the large variability in luminosity. High-spectral-resolution spectroscopic observation and monitoring will be key to revealing the property of the accretion process. Title: A Necessary Condition for Supernova Fallback Invading Newborn Neutron-star Magnetosphere Authors: Zhong, Yici; Kashiyama, Kazumi; Shigeyama, Toshikazu; Takasao, Shinsuke Bibcode: 2021ApJ...917...71Z Altcode: 2021arXiv210309461Z We numerically investigate the dynamics of a supernova fallback accretion confronting with a relativistic wind from a newborn neutron star (NS). The time evolution of the accretion shock in the radial direction is basically characterized by the encounter radius of the flow renc and a dimensionless parameter $\zeta \equiv L/{\dot{M}}_{\mathrm{fb}}{c}^{2}$ , where L is the NS wind luminosity and ${\dot{M}}_{\mathrm{fb}}$ is the fallback mass accretion rate. We find that the critical condition for the fallback matter to reach near the NS surface can be simply described as $\zeta \lt {\zeta }_{\min }\equiv {{GM}}_{* }/{c}^{2}{r}_{\mathrm{enc}}$ or ${r}_{\mathrm{enc}}L/{{GM}}_{* }{\dot{M}}_{\mathrm{fb}}\lt 1$ independent of the wind Lorentz factor, where M* is the NS mass. With combining the condition for the fallback matter to bury the surface magnetic field under the NS crust, we discuss the possibility that the trifurcation of NSs into rotation-powered pulsars, central compact objects, and magnetars can be induced by supernova fallback. Title: 3D MHD simulations of an accreting young star Authors: Takasao, Shinsuke; Tomida, Kengo; Iwasaki, Kazunari; Suzuki, Takeru Bibcode: 2021csss.confE.282T Altcode: Young stars such as protostars and pre-main-sequence stars evolve via the interaction with the surrounding accretion disks. It is believed that stellar and disk magnetic fields play important roles in shaping the accretion structure and exchanging the angular momentum between the stars and the disks. However, because of the complexity of gas dynamics around the stars, the star-disk interaction remains poorly understood, which makes the construction of the stellar evolution models difficult. To reveal the interaction processes, we have been performing 3D magnetohydrodynamic simulations of accretion onto a young star with different stellar magnetic fields. In the case of a weakly magnetized, magnetosphere-free star, we found that failed disk wind becomes supersonic, high-latitude accretion flows onto the star (Takasao et al. 2018). This result may explain the reason why Herbig Ae/Be stars show fast accretion. In a different model with stronger disk fields, we showed that the star can produce recurrent explosions via magnetic reconnection (Takasao et al. 2019). We consider that the mechanism is relevant to protostellar flares in class-0/I protostars. In addition to the above two models, we have been investigating the magnetospheric accretion which is very relevant to classical T-Tauri stars. In this talk, we will introduce our 3D modeling and discuss how the star-disk interaction changes depending on the stellar and disk field strengths. Title: Transition Region from Turbulent to Dead Zone in Protoplanetary Disks: Local Shearing Box Simulations Authors: Pucci, Fulvia; Tomida, Kengo; Stone, James; Takasao, Shinsuke; Ji, Hantao; Okamura, Shoichi Bibcode: 2021ApJ...907...13P Altcode: 2020arXiv201108219P The dynamical evolution of protoplanetary disks is of key interest for building a comprehensive theory of planet formation and to explain the observational properties of these objects. Using the magnetohydrodynamics code Athena++, with an isothermal shearing box setup, we study the boundary between the active and dead zone, where the accretion rate changes and mass can accumulate. We quantify how the turbulence level is affected by the presence of a non-uniform Ohmic resistivity in the radial x direction that leads to a region of inhibited turbulence (or dead zone). Comparing the turbulent activity to that of ideal simulations, the turbulence-inhibited area shows density fluctuations and magnetic activity at its boundaries, driven by energy injection from the active (ideal) zone boundaries. We find magnetic dissipation to be significantly stronger in the ideal regions, and the turbulence penetration through the boundary of the dead zone is determined by the value of the resistivity itself, through the Ohmic dissipation process, though the thickness of the transition does not play a significant role in changing the dissipation. We investigate the 1D spectra along the shearing direction: magnetic spectra appear flat at large scales both in ideal as well as resistive simulations, though a Kolmogorov scaling over more than one decade persists in the dead zone, suggesting the turbulent cascade is determined by the hydrodynamics of the system: magnetorotational instability dynamo action is inhibited where sufficiently high resistivity is present. Title: Estimation of Low-energy Cutoff of Non-thermal Electrons from a Spectro-polarimetric Observation Authors: Anan, T.; Yoneya, T.; Ichimoto, K.; Ueno, S.; Shiota, D.; Nozawa, S.; Takasao, S.; Kawate, T. Bibcode: 2020AGUFMSH0430015A Altcode: Low-energy cutoff of the non-thermal electron energy distribution is crucial to derive the total non-thermal electron energy. A flare kernel associated with a C4 class flare was observed in a spectral window including the He I triplet 1083.0 nm and Si I 1082.7 nm with a spectro-polarimeter on the Domeless Solar Telescope at Hida Observatory on 2015 August 9. The observed Stokes profiles of the He I triplet in the flare kernel are well reproduced through inversions considering the Zeeman and the Paschen-Back effects with a three-slab model of the flare kernel, in which two slabs which have upward and downward velocities produce emissions and one slab produces an absorption. The magnetic field strength inferred from the emission components of the He I line is 1400 G, which is significantly stronger than 690 G that is observed at the same location in the same line 6.5 hr before the flare. In addition, the photospheric magnetic field vector derived from the Si I10827 Å is similar to that of the flare kernel. To explain this result, we suggest that the emission in the He I triplet during the flare is produced in the deep layer, around which bombardment of non-thermal electrons leads to the formation of a coronal temperature plasma. Assuming a hydrogen column density at the location where the He I emissions are formed, and a power-law index of non-thermal electron energy distribution, we derived the low-energy cutoff of the non-thermal electron as 20-30 keV independently from methods using hard X-ray data. Title: Investigation of Coronal Properties of X-Ray Bright G-dwarf Stars Based on the Solar Surface Magnetic Field-Corona Relationship Authors: Takasao, Shinsuke; Mitsuishi, Ikuyuki; Shimura, Takuma; Yoshida, Atsushi; Kunitomo, Masanobu; Tanaka, Yuki A.; Ishihara, Daisuke Bibcode: 2020ApJ...901...70T Altcode: 2020arXiv200804255T We investigated the coronal properties of G-dwarf stars including the Sun over a wide range of X-ray luminosity LX (3 × 1026 to 2 × 1030 erg s-1). We analyzed the archival data of 10 X-ray bright (LX > 1028 erg s-1) G-dwarf stars to derive their emission measure (EM) and the coronal temperature (T) during the periods when no prominent stellar flares were observed. We attempted to explain the relation on the basis of our understanding of the present Sun: a steady corona model based on the so-called Rosner-Tucker-Vaiana (RTV) scaling laws and the observed power-law distribution function of surface magnetic features. We derived a theoretical scaling law of the EM-T relation for a star with multiple active regions, and applied it to the observations combined with data in the literature. We found that with the solar parameters, our scaling law seems to be consistent with the data of slowly rotating stars. However, more X-ray-bright stars are located well above the scaling law based on the solar parameter. The scaling law may explain the observations if those stars show a power-law distribution function of active regions with the same power-law index but a 10-100 times larger coefficient. This suggests that X-ray bright stars show more active regions for a given size than the Sun. Since our samples include rapidly rotating stars, we infer that the offset of the X-ray bright stars from the present Sun-based scaling law is due to the enhancement of the surface magnetic field generation by their rapid rotation. Title: Accretion Properties of PDS 70b with MUSE Authors: Hashimoto, Jun; Aoyama, Yuhiko; Konishi, Mihoko; Uyama, Taichi; Takasao, Shinsuke; Ikoma, Masahiro; Tanigawa, Takayuki Bibcode: 2020AJ....159..222H Altcode: 2020arXiv200307922H We report a new evaluation of the accretion properties of PDS 70b obtained with the Very Large Telescope/Multi Unit Spectroscopic Explorer. The main difference from the previous studies of Haffert et al. and Aoyama & Ikoma is in the mass accretion rate. Simultaneous multiple line observations, such as Hα and Hβ, can better constrain the physical properties of an accreting planet. While we clearly detected Hα emissions from PDS 70b, no Hβ emissions were detected. We estimate the line flux of Hβ with a 3σ upper limit to be 2.3 × 10-16 erg s-1 cm-2. The flux ratio FHβ/FHα for PDS 70b is <0.28. Numerical investigations by Aoyama et al. suggest that FHβ/FHα should be close to unity if the extinction is negligible. We attribute the reduction of the flux ratio to the extinction, and estimate the extinction of Hα (AHα) for PDS 70b to be >2.0 mag using the interstellar extinction value. By combining with the Hα linewidth and the dereddening line luminosity of Hα, we derive the PDS 70b mass accretion rate to be ≳5 × 10-7 MJup yr-1. The PDS 70b mass accretion rate is an order of magnitude larger than that of PDS 70. We found that the filling factor ff (the fractional area of the planetary surface emitting Hα) is ≳0.01, which is similar to the typical stellar value. The small value of ff indicates that the Hα emitting areas are localized at the surface of PDS 70b. Title: 3D simulations of accretion onto a star: Fast funnel-wall accretion Authors: Takasao, Shinsuke; Tomida, Kengo; Iwasaki, Kazunari; Suzuki, Takeru K. Bibcode: 2020IAUGA..30..138T Altcode: We show the results of global 3D magnetohydrodynamics simulations of an accretion disk with a rotating, weakly magnetized central star (Takasao et al. 2018). The disk is threaded by a weak large-scale poloidal magnetic field. The central star has no strong stellar magnetosphere initially and is only weakly magnetized. We investigate the structure of the accretion flows from a turbulent accretion disk onto the star. Our simulations reveal that fast accretion onto the star at high latitudes is established even without a stellar magnetosphere. We find that the failed disk wind becomes the fast, high-latitude accretion as a result of angular momentum exchange mediated by magnetic fields. The rapid angular momentum exchange occurs well above the disk, where the Lorentz force that decelerates the rotational motion of gas can be comparable to the centrifugal force. Unlike the classical magnetospheric accretion model, fast accretion streams are not guided by magnetic fields of the stellar magnetosphere. Nevertheless, the accretion velocity reaches the free-fall velocity at the stellar surface owing to the efficient angular momentum loss at a distant place from the star. Our model can be applied to Herbig Ae/Be stars whose magnetic fields are generally not strong enough to form magnetospheres, and also provides a possible explanation why Herbig Ae/Be stars show indications of fast accretion. Title: Comparative Study of Data-driven Solar Coronal Field Models Using a Flux Emergence Simulation as a Ground-truth Data Set Authors: Toriumi, Shin; Takasao, Shinsuke; Cheung, Mark C. M.; Jiang, Chaowei; Guo, Yang; Hayashi, Keiji; Inoue, Satoshi Bibcode: 2020ApJ...890..103T Altcode: 2020arXiv200103721T For a better understanding of the magnetic field in the solar corona and dynamic activities such as flares and coronal mass ejections, it is crucial to measure the time-evolving coronal field and accurately estimate the magnetic energy. Recently, a new modeling technique called the data-driven coronal field model, in which the time evolution of magnetic field is driven by a sequence of photospheric magnetic and velocity field maps, has been developed and revealed the dynamics of flare-productive active regions. Here we report on the first qualitative and quantitative assessment of different data-driven models using a magnetic flux emergence simulation as a ground-truth (GT) data set. We compare the GT field with those reconstructed from the GT photospheric field by four data-driven algorithms. It is found that, at minimum, the flux rope structure is reproduced in all coronal field models. Quantitatively, however, the results show a certain degree of model dependence. In most cases, the magnetic energies and relative magnetic helicity are comparable to or at most twice of the GT values. The reproduced flux ropes have a sigmoidal shape (consistent with GT) of various sizes, a vertically standing magnetic torus, or a packed structure. The observed discrepancies can be attributed to the highly non-force-free input photospheric field, from which the coronal field is reconstructed, and to the modeling constraints such as the treatment of background atmosphere, the bottom boundary setting, and the spatial resolution. Title: Comparative Study of Data-driven Coronal Field Models with a Ground-truth Flux Emergence Simulation Authors: Toriumi, S.; Takasao, S.; Cheung, C. M. M.; Jiang, C.; Guo, Y.; Hayashi, K.; Inoue, S. Bibcode: 2019AGUFMSH34B..04T Altcode: To better understand the dynamic activities in the so lar corona, it is desirable to follow the temporal evolution of coronal magnetic field and accurately measure the stored free magnetic energy. Data-driven coronal field models, in which the coronal field evolves in response to the sequentially updated photospheric field, have recently been developed and revealed the dynamics of flare-producing active regions. Here we report on the first attempt to qualitatively and quantitatively compare different data-driven models by using a magnetic flux emergence simulation as a ground-truth data set. We find that, at least, all models succeed in reproducing the twisted flux rope structure in the atmosphere. However, they show a certain degree of model dependence in, for instance, the structure of the flux rope, the rising speed, and the estimation of magnetic energy and helicity. In the presentation, we discuss the possible causes of the discrepancies, attributing them to the highly non-force-free input photospheric field, from which the coronal field is reconstructed, and the constraints in the data-driven models. Title: Giant Protostellar Flares: Accretion-driven Accumulation and Reconnection-driven Ejection of Magnetic Flux in Protostars Authors: Takasao, Shinsuke; Tomida, Kengo; Iwasaki, Kazunari; Suzuki, Takeru K. Bibcode: 2019ApJ...878L..10T Altcode: 2019arXiv190202007T Protostellar flares are rapid magnetic energy release events associated with the formation of hot plasma in protostars. In the previous models of protostellar flares, the interaction between a protostellar magnetosphere with the surrounding disk plays crucial role in building-up and releasing the magnetic energy. However, it remains unclear if protostars indeed have magnetospheres because vigorous disk accretion and strong disk magnetic fields in the protostellar phase may destroy the magnetosphere. Considering this possibility, we investigate the energy accumulation and release processes in the absence of a magnetosphere using a three-dimensional magnetohydrodynamic simulation. Our simulation reveals that protostellar flares are repeatedly produced even in such a case. Unlike in the magnetospheric models, the protostar accumulates magnetic energy by acquiring large-scale magnetic fields from the disk by accretion. Protostellar flares occur when a portion of the large-scale magnetic fields are removed from the protostar as a result of magnetic reconnection. Protostellar flares in the simulation are consistent with observations; the released magnetic energy (up to ∼3 × 1038 erg) is large enough to drive observed flares, and the flares produce hot ejecta. The expelled magnetic fields enhance accretion, and the energy build-up and release processes are repeated as a result. The magnetic flux removal via reconnection leads to redistribution of magnetic fields in the inner disk. We therefore consider that protostellar flares will play an important role in the evolution of the disk magnetic fields in the vicinity of protostars. Title: A New HLLD Riemann Solver with Boris Correction for Reducing Alfvén Speed Authors: Matsumoto, Tomoaki; Miyoshi, Takahiro; Takasao, Shinsuke Bibcode: 2019ApJ...874...37M Altcode: 2019arXiv190202810M A new Riemann solver is presented for the ideal magnetohydrodynamics (MHD) equations with the so-called Boris correction. The Boris correction is applied to reduce wave speeds, avoiding an extremely small timestep in MHD simulations. The proposed Riemann solver, Boris-HLLD, is based on the HLLD solver. As done by the original HLLD solver, (1) the Boris-HLLD solver has four intermediate states in the Riemann fan when left and right states are given, (2) it resolves the contact discontinuity, Alfvén waves, and fast waves, and (3) it satisfies all the jump conditions across shock waves and discontinuities except for slow shock waves. The results of a shock tube problem indicate that the scheme with the Boris-HLLD solver captures contact discontinuities sharply, and it exhibits shock waves without any overshoot when using the minmod limiter. The stability tests show that the scheme is stable when | u| ≲ 0.5c for a low Alfvén speed ({V}A≲ c), where u, c, and V A denote the gas velocity, speed of light, and Alfvén speed, respectively. For a high Alfvén speed ({V}A≳ c), where the plasma beta is relatively low in many cases, the stable region is large, | u| ≲ (0.6{--}1)c. We discuss the effect of the Boris correction on physical quantities using several test problems. The Boris-HLLD scheme can be useful for problems with supersonic flows in which regions with a very low plasma beta appear in the computational domain. Title: Measurement of vector magnetic field in a flare kernel with a spectropolarimetric observation in He I 10830 Å Authors: Anan, Tetsu; Yoneya, Takurou; Ichimoto, Kiyoshi; UeNo, Satoru; Shiota, Daikou; Nozawa, Satoshi; Takasao, Shinsuke; Kawate, Tomoko Bibcode: 2018PASJ...70..101A Altcode: 2018arXiv180806821A; 2018PASJ..tmp..113A A flare kernel associated with a C4 class flare was observed in a spectral window including the He I triplet 10830 Å and Si I 10827 Å with a spectropolarimeter on the Domeless Solar Telescope at Hida Observatory on 2015 August 9. The observed Stokes profiles of the He I triplet in the flare kernel in its post-maximum phase are well reproduced through inversions considering the Zeeman and the Paschen-Back effects with a three-slab model of the flare kernel, in which two slabs which have upward and downward velocities produce emissions and one slab produces an absorption. The magnetic field strength inferred from the emission components of the He I line is 1400 G, which is significantly stronger than 690 G that is observed at the same location in the same line 6.5 hr before the flare. In addition, the photospheric magnetic field vector derived from the Si I10827 Å is similar to that of the flare kernel. To explain this result, we suggest that the emission in the He I triplet during the flare is produced in the deep layer, around which bombardment of non-thermal electrons leads to the formation of a coronal temperature plasma. Assuming a hydrogen column density at the location where the He I emissions are formed, and a power-law index of non-thermal electron energy distribution, we derived the low-energy cutoff of the non-thermal electron as 20-30 keV, which is consistent with that inferred from hard X-ray data obtained by RHESSI. Title: Fast Accretion into a Weakly Magnetized Star Authors: Takasao, Shinsuke Bibcode: 2018tcl..confE..52T Altcode: Generally it has been assumed that the presence of a fast (close to the escape velocity) accretion is an indication of the magnetospheric accretion. However, observations indicate that fast accretion also occurs even in a weakly magnetized stars like Herbig Ae stars, which poses a question about the picture of accretion we have developed. We performed 3D MHD simulations by using the Athena++ code, and analyzed the accretion from an MRI (Magneto-Rotational Instability)-active disk onto a weakly magnetized star. As a result, we found that fast accretion to a high-latitude, which is similar to the magnetospheric accretion, is possible even without the stellar magnetosphere. Our results suggest a possibility that stars without the magnetosphere can show a violent accretion behavior associated with X-ray activities. We will discuss the physics of the accretion on the basis of our simulations. Title: A Three-dimensional Simulation of a Magnetized Accretion Disk: Fast Funnel Accretion onto a Weakly Magnetized Star Authors: Takasao, Shinsuke; Tomida, Kengo; Iwasaki, Kazunari; Suzuki, Takeru K. Bibcode: 2018ApJ...857....4T Altcode: 2018arXiv180107245T We present the results of a global, three-dimensional magnetohydrodynamics simulation of an accretion disk with a rotating, weakly magnetized central star. The disk is threaded by a weak, large-scale poloidal magnetic field, and the central star has no strong stellar magnetosphere initially. Our simulation investigates the structure of the accretion flows from a turbulent accretion disk onto the star. The simulation reveals that fast accretion onto the star at high latitudes occurs even without a stellar magnetosphere. We find that the failed disk wind becomes the fast, high-latitude accretion as a result of angular momentum exchange mediated by magnetic fields well above the disk, where the Lorentz force that decelerates the rotational motion of gas can be comparable to the centrifugal force. Unlike the classical magnetospheric accretion scenario, fast accretion streams are not guided by magnetic fields of the stellar magnetosphere. Nevertheless, the accretion velocity reaches the free-fall velocity at the stellar surface due to the efficient angular momentum loss at a distant place from the star. This study provides a possible explanation why Herbig Ae/Be stars whose magnetic fields are generally not strong enough to form magnetospheres also show indications of fast accretion. A magnetically driven jet is not formed from the disk in our model. The differential rotation cannot generate sufficiently strong magnetic fields for the jet acceleration because the Parker instability interrupts the field amplification. Title: Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares Authors: McLaughlin, J. A.; Nakariakov, V. M.; Dominique, M.; Jelínek, P.; Takasao, S. Bibcode: 2018SSRv..214...45M Altcode: 2018arXiv180204180M Solar flare emission is detected in all EM bands and variations in flux density of solar energetic particles. Often the EM radiation generated in solar and stellar flares shows a pronounced oscillatory pattern, with characteristic periods ranging from a fraction of a second to several minutes. These oscillations are referred to as quasi-periodic pulsations (QPPs), to emphasise that they often contain apparent amplitude and period modulation. We review the current understanding of quasi-periodic pulsations in solar and stellar flares. In particular, we focus on the possible physical mechanisms, with an emphasis on the underlying physics that generates the resultant range of periodicities. These physical mechanisms include MHD oscillations, self-oscillatory mechanisms, oscillatory reconnection/reconnection reversal, wave-driven reconnection, two loop coalescence, MHD flow over-stability, the equivalent LCR-contour mechanism, and thermal-dynamical cycles. We also provide a histogram of all QPP events published in the literature at this time. The occurrence of QPPs puts additional constraints on the interpretation and understanding of the fundamental processes operating in flares, e.g. magnetic energy liberation and particle acceleration. Therefore, a full understanding of QPPs is essential in order to work towards an integrated model of solar and stellar flares. Title: Numerical Modeling of Flare-productive Active Regions of the Sun Authors: Toriumi, S.; Takasao, S. Bibcode: 2017AGUFMSH43C..07T Altcode: It is known that strong flare events on the Sun take place in active regions (ARs), especially in delta sunspots with closely-packed positive and negative polarities. The delta spots are produced as a result of complex magnetic flux emergence and have strong-field, highly-sheared polarity inversion lines (PILs). Here we report on the numerical simulations of four types of such flare-productive ARs, namely, (1) Spot-Spot, a complex AR with AR-sized PIL, (2) Spot-Satellite, in which a newly-emerging bipole appears next to the pre-existing sunspot, (3) Quadrupole, where two emerging bipoles collide against each other, and (4) Inter-AR, the flares occurring between two separated ARs. We reproduced these four cases by conducting a series of 3D MHD flux emergence simulations and found, for example, that the sheared PILs in these ARs are created through the stretching and advection of horizontal magnetic fields due to relative spot motions. As ARs develop, free magnetic energy becomes stored in the corona, which could be eventually released through flare eruptions. In the presentation, we also mention the relationship between the HMI/SHARP parameters measured in the photosphere and the free energy stored in the corona, and discuss why these parameters successfully predict the flares. Title: Numerical Simulations of Flare-productive Active Regions: δ-sunspots, Sheared Polarity Inversion Lines, Energy Storage, and Predictions Authors: Toriumi, Shin; Takasao, Shinsuke Bibcode: 2017ApJ...850...39T Altcode: 2017arXiv171008926T Solar active regions (ARs) that produce strong flares and coronal mass ejections (CMEs) are known to have a relatively high non-potentiality and are characterized by δ-sunspots and sheared magnetic structures. In this study, we conduct a series of flux emergence simulations from the convection zone to the corona and model four types of active regions that have been observationally suggested to cause strong flares, namely the spot-spot, spot-satellite, quadrupole, and inter-AR cases. As a result, we confirm that δ-spot formation is due to the complex geometry and interaction of emerging magnetic fields, and we find that the strong-field, high-gradient, highly sheared polarity inversion line (PIL) is created by the combined effect of the advection, stretching, and compression of magnetic fields. We show that free magnetic energy builds up in the form of a current sheet above the PIL. It is also revealed that photospheric magnetic parameters that predict flare eruptions reflect the stored free energy with high accuracy, while CME-predicting parameters indicate the magnetic relationship between flaring zones and entire ARs. Title: A Theoretical Model of X-Ray Jets from Young Stellar Objects Authors: Takasao, Shinsuke; Suzuki, Takeru K.; Shibata, Kazunari Bibcode: 2017ApJ...847...46T Altcode: 2017arXiv170805388T There is a subclass of X-ray jets from young stellar objects that are heated very close to the footpoint of the jets, particularly DG Tau jets. Previous models have attributed the strong heating to shocks in the jets. However, the mechanism that localizes the heating at the footpoint remains puzzling. We presented a different model of such X-ray jets, in which the disk atmosphere is magnetically heated. Our disk corona model is based on the so-called nanoflare model for the solar corona. We show that the magnetic heating near the disks can result in the formation of a hot corona with a temperature of ≳106 K, even if the average field strength in the disk is moderately weak, ≳1 G. We determine the density and the temperature at the jet base by considering the energy balance between the heating and cooling. We derive the scaling relations of the mass-loss rate and terminal velocity of jets. Our model is applied to the DG Tau jets. The observed temperature and estimated mass-loss rate are consistent with the prediction of our model in the case of a disk magnetic field strength of ∼20 G and a heating region of <0.1 au. The derived scaling relation of the temperature of X-ray jets could be a useful tool for estimating the magnetic field strength. We also find that the jet X-ray can have a significant impact on the ionization degree near the disk surface and the dead zone size. Title: “Dandelion” Filament Eruption and Coronal Waves Associated with a Solar Flare on 2011 February 16 Authors: Cabezas, Denis P.; Martínez, Lurdes M.; Buleje, Yovanny J.; Ishitsuka, Mutsumi; Ishitsuka, José K.; Morita, Satoshi; Asai, Ayumi; UeNo, Satoru; Ishii, Takako T.; Kitai, Reizaburo; Takasao, Shinsuke; Yoshinaga, Yusuke; Otsuji, Kenichi; Shibata, Kazunari Bibcode: 2017ApJ...836...33C Altcode: 2017arXiv170100308C Coronal disturbances associated with solar flares, such as Hα Moreton waves, X-ray waves, and extreme ultraviolet (EUV) coronal waves, are discussed herein in relation to magnetohydrodynamic fast-mode waves or shocks in the corona. To understand the mechanism of coronal disturbances, full-disk solar observations with high spatial and temporal resolution over multiple wavelengths are of crucial importance. We observed a filament eruption, whose shape is like a “dandelion,” associated with the M1.6 flare that occurred on 2011 February 16 in Hα images taken by the Flare Monitoring Telescope at Ica University, Peru. We derive the three-dimensional velocity field of the erupting filament. We also identify winking filaments that are located far from the flare site in the Hα images, whereas no Moreton wave is observed. By comparing the temporal evolution of the winking filaments with those of the coronal wave seen in the EUV images data taken by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and by the Extreme Ultraviolet Imager on board the Solar Terrestrial Relations Observatory-Ahead, we confirm that the winking filaments were activated by the EUV coronal wave. Title: Observational Evidence of Particle Acceleration Associated with Plasmoid Motions Authors: Takasao, Shinsuke; Asai, Ayumi; Isobe, Hiroaki; Shibata, Kazunari Bibcode: 2016ApJ...828..103T Altcode: 2016arXiv161100108T We report a strong association between the particle acceleration and plasma motions found in the 2010 August 18 solar flare. The plasma motions are tracked in the extreme ultraviolet (EUV) images taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory and the Extreme UltraViolet Imager (EUVI) on the Solar Terrestrial Relations Observatory spacecraft Ahead, and the signature of particle acceleration was investigated by using Nobeyama Radioheliograph data. In our previous paper, we reported that in EUV images many plasma blobs appeared in the current sheet above the flare arcade. They were ejected bidirectionally along the current sheet, and the blobs that were ejected sunward collided with the flare arcade. Some of them collided or merged with each other before they were ejected from the current sheet. We discovered impulsive radio bursts associated with such plasma motions (ejection, coalescence, and collision with the post flare loops). The radio bursts are considered to be the gyrosynchrotron radiation by nonthermal high energy electrons. In addition, the stereoscopic observation by AIA and EUVI suggests that plasma blobs had a three-dimensionally elongated structure. We consider that the plasma blobs were three-dimensional plasmoids (I.e., flux ropes) moving in a current sheet. We believe that our observation provides clear evidence of particle acceleration associated with the plasmoid motions. We discuss possible acceleration mechanisms on the basis of our results. Title: Above-the-loop-top Oscillation and Quasi-periodic Coronal Wave Generation in Solar Flares Authors: Takasao, Shinsuke; Shibata, Kazunari Bibcode: 2016ApJ...823..150T Altcode: 2016arXiv160609354T Observations revealed that various kinds of oscillations are excited in solar flare regions. Quasi-periodic pulsations (QPPs) in flare emissions are commonly observed in a wide range of wavelengths. Recent observations have found that fast-mode magnetohydrodynamic (MHD) waves are quasi-periodically emitted from some flaring sites (quasi-periodic propagating fast-mode magnetoacoustic waves; QPFs). Both QPPs and QPFs imply a cyclic disturbance originating from the flaring sites. However, the physical mechanisms remain puzzling. By performing a set of two-dimensional MHD simulations of a solar flare, we discovered the local oscillation above the loops filled with evaporated plasma (above-the-loop-top region) and the generation of QPFs from such oscillating regions. Unlike all previous models for QPFs, our model includes essential physics for solar flares such as magnetic reconnection, heat conduction, and chromospheric evaporation. We revealed that QPFs can be spontaneously excited by the above-the-loop-top oscillation. We found that this oscillation is controlled by the backflow of the reconnection outflow. The new model revealed that flare loops and the above-the-loop-top region are full of shocks and waves, which is different from the previous expectations based on a standard flare model and previous simulations. In this paper, we show the QPF generation process based on our new picture of flare loops and will briefly discuss a possible relationship between QPFs and QPPs. Our findings will change the current view of solar flares to a new view in which they are a very dynamic phenomenon full of shocks and waves. Title: The formation and evolution of reconnection-driven, slow-mode shocks in a partially ionised plasma Authors: Hillier, A.; Takasao, S.; Nakamura, N. Bibcode: 2016A&A...591A.112H Altcode: 2016arXiv160201112H The role of slow-mode magnetohydrodynamic (MHD) shocks in magnetic reconnection is of great importance for energy conversion and transport, but in many astrophysical plasmas the plasma is not fully ionised. In this paper, we use numerical simulations to investigate the role of collisional coupling between a proton-electron, charge-neutral fluid and a neutral hydrogen fluid for the one-dimensional (1D) Riemann problem initiated in a constant pressure and density background state by a discontinuity in the magnetic field. This system, in the MHD limit, is characterised by two waves. The first is a fast-mode rarefaction wave that drives a flow towards a slow-mode MHD shock wave. The system evolves through four stages: initiation, weak coupling, intermediate coupling, and a quasi-steady state. The initial stages are characterised by an over-pressured neutral region that expands with characteristics of a blast wave. In the later stages, the system tends towards a self-similar solution where the main drift velocity is concentrated in the thin region of the shock front. Because of the nature of the system, the neutral fluid is overpressured by the shock when compared to a purely hydrodynamic shock, which results in the neutral fluid expanding to form the shock precursor. Once it has formed, the thickness of the shock front is proportional to ξ I-1.2 , which is a smaller exponent than would be naively expected from simple scaling arguments. One interesting result is that the shock front is a continuous transition of the physical variables of subsonic velocity upstream of the shock front (a c-shock) to a sharp jump in the physical variables followed by a relaxation to the downstream values for supersonic upstream velocity (a j-shock). The frictional heating that results from the velocity drift across the shock front can amount to ~2 per cent of the reference magnetic energy. Title: Fractal Reconnection in Solar and Stellar Environments Authors: Shibata, K.; Takasao, S. Bibcode: 2016ASSL..427..373S Altcode: 2016arXiv160609401S Recent space based observations of the Sun revealed that magnetic reconnection is ubiquitous in the solar atmosphere, ranging from small scale reconnection (observed as nanoflares) to large scale one (observed as long duration flares or giant arcades). Often the magnetic reconnection events are associated with mass ejections or jets, which seem to be closely related to multiple plasmoid ejections from fractal current sheet. The bursty radio and hard X-ray emissions from flares also suggest the fractal reconnection and associated particle acceleration. We shall discuss recent observations and theories related to the plasmoid-induced-reconnection and the fractal reconnection in solar flares, and their implication to reconnection physics and particle acceleration. Recent findings of many superflares on solar type stars that has extended the applicability of the fractal reconnection model of solar flares to much a wider parameter space suitable for stellar flares are also discussed. Title: Numerical Study on the Emergence of Kinked Flux Tube for Understanding of Possible Origin of δ-spot Regions Authors: Takasao, Shinsuke; Fan, Yuhong; Cheung, Mark C. M.; Shibata, Kazunari Bibcode: 2015ApJ...813..112T Altcode: 2015arXiv151102863T We carried out an magnetohydrodynamic simulation where a subsurface twisted kink-unstable flux tube emerges from the solar interior to the corona. Unlike the previous expectations based on the bodily emergence of a knotted tube, we found that the kinked tube can spontaneously form a complex quadrupole structure at the photosphere. Due to the development of the kink instability before the emergence, the magnetic twist at the kinked apex of the tube is greatly reduced, although the other parts of the tube are still strongly twisted. This leads to the formation of a complex quadrupole structure: a pair of the coherent, strongly twisted spots and a narrow complex bipolar pair between it. The quadrupole is formed by the submergence of a portion of emerged magnetic fields. This result is relevant for understanding the origin of the complex multipolar δ-spot regions that have a strong magnetic shear and emerge with polarity orientations not following Hale-Nicholson and Joy Laws. Title: A Theoretical Model of a Thinning Current Sheet in the Low-β Plasmas Authors: Takeshige, Satoshi; Takasao, Shinsuke; Shibata, Kazunari Bibcode: 2015ApJ...807..159T Altcode: 2015arXiv150405677T Magnetic reconnection is an important physical process in various explosive phenomena in the universe. In previous studies, it was found that fast reconnection takes place when the thickness of a current sheet becomes on the order of a microscopic length such as the ion Larmor radius or the ion inertial length. In this study, we investigated the pinching process of a current sheet by the Lorentz force in a low-β plasma using one-dimensional magnetohydrodynamics (MHD) simulations. It is known that there is an exact self-similar solution for this problem that neglects gas pressure. We compared the non-linear MHD dynamics with the analytic self-similar solution. From the MHD simulations, we found that with the gas pressure included the implosion process deviates from the analytic self-similar solution as t\to {t}0, where t0 is the explosion time when the thickness of a current sheet of the analytic solution becomes 0. We also found that a pair of MHD fast-mode shocks is generated and propagates after the formation of the pinched current sheet as t\to {t}0. On the basis of the Rankine-Hugoniot relations, we derived the scaling law of the physical quantities with respect to the initial plasma beta in the pinched current sheet. Our study could help us estimate the physical quantities in the pinched current sheet formed in a low-β plasma. Title: Magnetohydrodynamic Shocks in and above Post-flare Loops: Two-dimensional Simulation and a Simplified Model Authors: Takasao, Shinsuke; Matsumoto, Takuma; Nakamura, Naoki; Shibata, Kazunari Bibcode: 2015ApJ...805..135T Altcode: 2015arXiv150405700T Solar flares are an explosive phenomenon where super-sonic flows and shocks are expected in and above the post-flare loops. To understand the dynamics of post-flare loops, a two-dimensional magnetohydrodynamic (2D MHD) simulation of a solar flare has been carried out. We found new shock structures in and above the post-flare loops, which were not resolved in the previous work by Yokoyama & Shibata. To study the dynamics of flows along the reconnected magnetic field, the kinematics and energetics of the plasma are investigated along selected field lines. It is found that shocks are crucial to determine the thermal and flow structures in the post-flare loops. On the basis of the 2D MHD simulation, we developed a new post-flare loop model, which we defined as the pseudo-2D MHD model. The model is based on the one-dimensional (1D) MHD equations, where all variables depend on one space dimension, and all the three components of the magnetic and velocity fields are considered. Our pseudo-2D model includes many features of the multi-dimensional MHD processes related to magnetic reconnection (particularly MHD shocks), which the previous 1D hydrodynamic models are not able to include. We compared the shock formation and energetics of a specific field line in the 2D calculation with those in our pseudo-2D MHD model, and found that they give similar results. This model will allow us to study the evolution of the post-flare loops in a wide parameter space without expensive computational cost or neglecting important physics associated with magnetic reconnection. Title: Within the International Collaboration CHAIN: a Summary of Events Observed with Flare Monitoring Telescope (FMT) in Peru Authors: Ishitsuka, J.; Asai, A.; Morita, S.; Terrazas, R.; Cabezas, D.; Gutierrez, V.; Martinez, L.; Buleje, Y.; Loayza, R.; Nakamura, N.; Takasao, S.; Yoshinaga, Y.; Hillier, A.; Otsuji, K.; Shibata, K.; Ishitsuka, M.; Ueno, S.; Kitai, R.; Ishii, T.; Ichimoto, K.; Nagata, S.; Narukage, N. Bibcode: 2014SunGe...9...85I Altcode: In 2008 we inaugurated the new Solar Observatory in collaboration with Faculty of Sciences of San Luis Gonzaga de Ica National University, 300 km south of Lima. In March of 2010 a Flare Monitoring Telescope of Hida Observatory of Kyoto University arrived to Ica, part of CHAIN Project (Continuous H-alpha Imaging Network). In October of the same year we hosted the First FMT Workshop in Ica, then in July of 2011 the Second FMT Workshop was opened. Since that we are focused on two events registered by FMT in Peru to publish results. FMT is a good tool to introduce young people from universities into scientific knowledge; it is good also for education in Solar Physics and outreach. Details of this successful collaboration will be explained in this presentation. Title: Numerical Experiments of Flux Emergence of Kinked Flux Tubes into Solar Atmosphere Authors: Takasao, Shinsuke; Fan, Yuhong Bibcode: 2014cosp...40E3280T Altcode: The so-called “delta-sunspots” are known to be among the most flare-productive active regions in the solar atmosphere. Observations show that a fraction of the delta-spots emerge with strong magnetic shear and with polarity orientations not following the Hale-polarity rule obeyed by the majority of active regions. To understand the observed evolution of these active regions and the origin of their high magnetic activity, we carried out MHD simulations in which a subsurface twisted flux tube with kinked or knotted geometry emerges from the convection zone into the solar atmosphere. From the numerical experiments, we found the followings: 1. Although the initial twist is strong, the magnetic shear near the apex is reduced due to kinking in the early phase of the emergence. This leads to a larger growth rate of the magnetic Rayleigh-Taylor (RT) instability, and therefore many current sheets are formed due to RT instability. 2. The current carried by the twisted flux tube in the convection zone, which can be the main source of the free energy, is transported to the upper atmosphere by the torsional Alfven wave. 3. Magnetic reconnections take place above the neutral line at the photosphere. This causes the plasma ejections in the corona. We will give a detailed picture of the emergence of a kinked flux tube on the basis of the numerical experiments, and clarify the difference between the unkinked tube emergence and the kinked tube emergence. These results could be important for understanding the magnetic field evolution in flare productive active regions. Title: Numerical Simulations of Solar Chromospheric Jets Associated with Emerging Flux Authors: Takasao, Shinsuke; Isobe, Hiroaki; Shibata, Kazunari Bibcode: 2013PASJ...65...62T Altcode: 2013arXiv1301.7325T We studied the acceleration mechanisms of chromospheric jets associated with emerging flux using a two-dimensional magnetohydrodynamic (MHD) simulation. We found that slow-mode shock waves generated by magnetic reconnection in the chromosphere and the photosphere play key roles in the acceleration mechanisms of chromospheric jets. An important parameter is the height of magnetic reconnection. When magnetic reconnection takes place near the photosphere, the reconnection outflow collides with the region where the plasma beta is much larger than unity. Then, the plasma moves along a magnetic field. This motion generates a slow-mode wave. The slow-mode wave develops to a strong slow shock as it propagates upward. When the slow shock crosses the transition region, this region is lifted up. As a result, we obtain a chromospheric jet as the lifted transition region. When magnetic reconnection takes place in the upper chromosphere, the chromospheric plasma is accelerated due to the combination of the Lorentz force and the whip-like motion of the magnetic field. We found that the chromospheric plasma is further accelerated through the interaction between the transition region (steep density gradient) and a slow shock emanating from the reconnection point. In the process, the magnetic energy released by magnetic reconnection is efficiently converted into the kinetic energy of jets. This is an MHD effect that has not been discussed before. Title: Dynamic Features of Current Sheet Associated with the 2010 August 18 Solar Flare Authors: Takasao, S.; Asai, A.; Isobe, H.; Shibata, K. Bibcode: 2012ASPC..456..221T Altcode: We report the observation of the magnetic reconnection site in the 2010 August 18 flare. We simultaneously found both reconnection inflow and outflow. By using these velocities, we estimated the nondimensional reconnection rate and found that it varied from 0.20 to 0.055. We also observed dynamic plasma blobs in the sheet structure. The plasma blobs collided with the hot loops and radio emissions were found at this site, which may suggest particle acceleration. We hypothesize that the sheet structure is the current sheet and that these plasma blobs are plasmoids, which could be important for understanding the dynamics of the reconnection region. Title: Observation of Dynamic Features of Current Sheet Associated with 2010 August 18 Solar Flare Authors: Takasao, S.; Asai, A.; Isobe, H.; Shibata, K. Bibcode: 2012decs.confE..93T Altcode: We report the simultaneous extreme-ultraviolet observation of magnetic reconnection inflow and outflow in a flare on 2010 August 18 observed by SDO/AIA. We found that during the rise phase of the flare, some plasma blobs appeared in a sheet structure above hot loops. The plasma blobs were ejected bidirectionally along the sheet structure (i.e. reconnection outflow). Simultaneously, bright threads visible in the extreme-ultraviolet images moved toward the sheet structure (i.e. reconnection inflow). Using the velocities of the inflow and outflow, we estimated the non-dimensional reconnection rate and found it varies during this period from 0.20 to 0.055. We also found that the plasma blobs in the sheet structure collided and possibly merged with each other before they were ejected from the sheet structure. From these observational results, we hypothesize that the sheet structure is the current sheet and that these plasma blobs are plasmoids or magnetic islands. This observational report could be important for understanding the dynamics of the reconnection region. Title: Simultaneous Observation of Reconnection Inflow and Outflow Associated with the 2010 August 18 Solar Flare Authors: Takasao, Shinsuke; Asai, Ayumi; Isobe, Hiroaki; Shibata, Kazunari Bibcode: 2012ApJ...745L...6T Altcode: 2011arXiv1112.1398T We report the simultaneous extreme-ultraviolet observation of magnetic reconnection inflow and outflow in a flare on 2010 August 18 observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We found that during the rise phase of the flare, some plasma blobs appeared in the sheet structure above the hot loops. The plasma blobs were ejected bidirectionally along the sheet structure (outflow), at the same time as the threads visible in extreme-ultraviolet images moved toward the sheet structure (inflow). The upward and downward ejection velocities are 220-460 km s-1 and 250-280 km s-1, respectively. The inflow speed changed from 90 km s-1 to 12 km s-1 in 5 minutes. By using these velocities, we estimated the nondimensional reconnection rate, which we found to vary during this period from 0.20 to 0.055. We also found that the plasma blobs in the sheet structure collided or merged with each other before they were ejected from the sheet structure. We hypothesize that the sheet structure is the current sheet and that these plasma blobs are plasmoids or magnetic islands, which could be important for understanding the dynamics of the reconnection region.