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Monash Astro Seminars
3pm, Tuesday 01 December 2009; Maths, Rm. 345
Elena Khomenko
"Modeling of waves in solar magnetic structures"
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The magnetized photosphere and chromosphere of the Sun are regions where different physical agents come into play with almost equal weight. The restoring forces in the wave equation, such as magnetic Lorentz force, gas pressure gradient and buoyancy, are of the same order of magnitude, making arbitrary the division into pure wave modes and complicating theoretical models. In this talk I will discuss my recent results on numerical simulations of waves in sunspots and small-scale flux tubes, in the context of new results from high-resolution observations and analytical theories. The broad objective of my work is to find answers to questions like those listed below:
(i) How can the oscillations observed in different magnetic structures be interpreted in terms of magneto-hydrodynamic waves? What are the relationships between photospheric and chromospheric oscillations? What causes the complex spatial pattern of oscillations such as chromospheric umbral flashes and penumbral waves in sunspots?
(ii) Are there observational evidences of the mode transformation in active regions? What are the reasons for the spatial power distribution at different frequency intervals, as revealed by high-resolution observations?
(iii) What is the possible contribution of high-frequency and low-frequency waves to the energy transport to the chromosphere? How is the spectrum of waves modified by the magnetic field?
(iv) What is the source of the helioseismological velocity signal observed in active regions? In which way the strong magnetic field in active regions can influence the retrieval of their sub-surface structure using standard helioseismological methods?
Despite these questions seem to be many, they have a common factor, i.e., magnetic field, which helps creating a unified picture describing the wave dynamics in the magnetized solar atmosphere.
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Please email all enquiries to daniel.price@sci.monash.edu.au or rosemary.mardling@sci.monash.edu.au
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