Numerical simulations of solar macrospicules

Murawski, K.; Srivastava, A. K.; Zaqarashvili, T. V.

doi:10.1051/0004-6361/201117589

Cited by 59 publications

(75 citation statements)

References 29 publications

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“…Numerical simulations suggest that in the open-field configuration two different types of jets can exist, one of which presumably corresponds to macrospicules, scarcely seen in Hα because of their low density (Shibata 1982). Although some of the macrospicules' properties observed in the EUV have been reproduced in simulations, the formation mechanism of macrospicules remains an unresolved problem (Andreev & Kosovichev 1994;Murawski et al 2011 Some authors note that macrospicules have approximately the same velocities as the recently discovered Type II spicules (discovered by de Pontieu et al 2007b), and moreover, that they are both predominantly observed in the coronal holes, which indicates that these phenomena can be closely related (Sterling et al 2010). It was estimated that the amount of energy required to produce a macrospicule exceeds that required for an ordinary spicule by roughly two orders of magnitude, and therefore, macrospicules should be considered an important factor in the mass and energy balance of the corona (Withbroe et al 1976).…”

Section: Introductionmentioning

confidence: 99%

Plasma dynamics in solar macrospicules from high-cadence extreme-UV observations

Loboda

Богачев

2017

A&A

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Macrospicules are relatively large spicule-like formations found mainly over the polar coronal holes when observing in the transition region spectral lines. In this study, we took advantage of the two short series of observations in the He ii 304 Å line obtained by the TESIS solar observatory with a cadence of up to 3.5 s to study the dynamics of macrospicules in unprecedented detail. We used a one-dimensional hydrodynamic method based on the assumption of their axial symmetry and on a simple radiative transfer model to reconstruct the evolution of the internal velocity field of 18 macrospicules from this dataset. Besides the internal dynamics, we studied the motion of the apparent end points of the same 18 macrospicules and found 15 of them to follow parabolic trajectories with high precision which correspond closely to the obtained velocity fields. We found that in a clear, unperturbed case these macrospicules move with a constant deceleration inconsistent with a purely ballistic motion and have roughly the same velocity along their entire axis, with the obtained decelerations typically ranging from 160 to 230 m s −2 , and initial velocities from 80 to 130 km s −1 . We also found a propagating acoustic wave for one of the macrospicules and a clear linear correlation between the initial velocities of the macrospicules and their decelerations, which indicates that they may be driven by magneto-acoustic shocks. Finally, we inverted our previous method by taking velocities from the parabolic fits to give rough estimates of the percentage of mass lost by 12 of the macrospicules. We found that typically from 10 to 30% of their observed mass fades out of the line (presumably being heated to higher coronal temperatures) with three exceptions of 50% and one of 80%.

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Section: Introductionmentioning

confidence: 99%

Plasma dynamics in solar macrospicules from high-cadence extreme-UV observations

Loboda

Богачев

2017

A&A

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“…The line is often used for the study of filaments and prominences (Liewer et al 2009;Bi et al 2012;Labrosse & McGlinchey 2012). Another recent example of its use is for the study of spicules (Murawski et al 2011) and heating events associated with them (De Pontieu et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Detailed and Simplified Nonequilibrium Helium Ionization in the Solar Atmosphere

Golding

Carlsson

Leenaarts

2014

ApJ

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Helium ionization plays an important role in the energy balance of the upper chromosphere and transition region. Helium spectral lines are also often used as diagnostics of these regions. We carry out one-dimensional radiation-hydrodynamics simulations of the solar atmosphere and find that the helium ionization is set mostly by photoionization and direct collisional ionization, counteracted by radiative recombination cascades. By introducing an additional recombination rate mimicking the recombination cascades, we construct a simplified three-level helium model atom consisting of only the ground states. This model atom is suitable for modeling nonequilibrium helium ionization in three-dimensional numerical models. We perform a brief investigation of the formation of the He i 10830 and He ii 304 spectral lines. Both lines show nonequilibrium features that are not recovered with statistical equilibrium models, and caution should therefore be exercised when such models are used as a basis for interpretating observations.

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“…On the other hand, waves generated by reconnection could also display these timescales. Murawski & Zaqarashvili (2010); Murawski et al (2011) performed numerical simulations of solar spicules and macro-spicules. They studied the upward propagation of a localized velocity pulse that is initially launched below the transition region.…”

Section: Zaqarashvili and Erdélyi 2009mentioning

confidence: 99%

Observation of kink waves and their reconnection-like origin in solar spicules

Ebadi

Ghiassi

2014

Astrophys Space Sci

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We analyze the time series of Ca ii H-line obtained from Hinode/SOT on the solar limb. We follow three cases of upwardly propagating kink waves along a spicule and inverted Y-shaped structures at the cusp of it. The time-distance analysis shows that the axis of spicule undergos quasi-periodic transverse displacement at different heights from the photosphere. The mean period of transverse displacement is ∼175 s and the mean amplitude is 1 arc sec. The oscillation periods are increasing linearly with height which may be counted as the signature that the spicule is working as a low pass filter and allows only the low frequencies to propagate towards higher heights. The oscillations amplitude is increasing with height due to decrease in density. The phase speeds are increasing until some heights and then decreasing which may be related to the small scale reconnection at the spicule basis. We conclude that transversal displacement of spicules axis can be related to the propagation of kink waves along them. Moreover, we observe signatures of small-scale magnetic reconnection at the cusp of spicules which may excite kink waves.

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Numerical simulations of solar macrospicules

Cited by 59 publications

References 29 publications

Plasma dynamics in solar macrospicules from high-cadence extreme-UV observations

Plasma dynamics in solar macrospicules from high-cadence extreme-UV observations

Detailed and Simplified Nonequilibrium Helium Ionization in the Solar Atmosphere

Observation of kink waves and their reconnection-like origin in solar spicules

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