Fundamental (f) Oscillations in a Magnetically Coupled Solar Interior-Atmosphere System:An Analytical Approach

Solar fundamental (f) acoustic mode oscillations are investigated analytically in a magnetohydrodynamic (MHD) model. The model consists of three layers in planar geometry, representing the solar interior, the magnetic atmosphere, and a transitional layer sandwiched between them. Since we focus on the fundamental mode here, we assume the plasma is incompressible. A horizontal, canopy-like, magnetic field is introduced to the atmosphere, in which degenerated slow MHD waves can exist. The global (f-mode) oscillations can couple to local atmospheric Alfvén waves, resulting, e.g., in a frequency shift of the oscillations. The dispersion relation of the global oscillation mode is derived, and is solved analytically for the thin-transitional layer approximation and for the weak-field approximation. Analytical formulae are also provided for the frequency shifts due to the presence of a thin transitional layer and a weak atmospheric magnetic field. The analytical results generally indicate that, compared to the fundamental value (ω=gk), the mode frequency is reduced by the presence of an atmosphere by a few per cent. A thin transitional layer reduces the eigen-frequencies further by about an additional hundred microhertz. Finally, a weak atmospheric magnetic field can slightly, by a few percent, increase the frequency of the eigen-mode. Stronger magnetic fields, however, can increase the f-mode frequency by even up to ten per cent, which cannot be seen in observed data. The presence of a magnetic atmosphere in the three-layer model also introduces non-permitted propagation windows in the frequency spectrum; here, f-mode oscillations cannot exist with certain values of the harmonic degree. The eigen-frequencies can be sensitive to the background physical parameters, such as an atmospheric density scale-height or the rate of the plasma density drop at the photosphere. Such information, if ever observed with high-resolution instrumentation and inverted, could help to gain further insight into solar magnetic structures by means of solar magneto-seismology, and could provide further insight into the role of magnetism in solar oscillations

Global oscillations in a magnetic solar model:II Oblique propagation

The coupling of solar global acoustic oscillations to a magnetised solar atmosphere is studied here. The solar interior – atmosphere interface is modelled by a non-magnetic polytrope interior overlayed by a planar atmosphere embedded in non-uniform horizontal atmospheric magnetic field. Pintér & Goossens (1999, A&A, 347, 321) showed that parallel propagating acoustic waves can couple resonantly to local magnetohydrodynamic (MHD) slow continuum modes only. In general, global acoustic modes can, however, propagate in arbitrary directions with respect to local atmospheric fields giving rise to an additional efficient coupling mechanism that has consequences on mode damping and atmospheric energetics. In this paper we study obliquely propagating global modes that can couple also to local MHD Alfvén continuum modes. The atmospheric magnetic effects on global mode frequencies are still much of a debate. In particular, the resulting frequency shifts and damping rates of global modes caused by the resonant interaction with both local Alfvén and slow waves are investigated. We found the coupling of global f and p modes and the Lamb mode, that penetrate into the magnetic solar atmosphere, will strongly depend on the direction of propagation with respect to the solar atmospheric magnetic field. These frequency shifts, as a function of the propagation direction, give us a further elegant tool and refinement method of local helioseismology techniques. Finally we briefly discuss the importance of studying obliquely propagating waves and discuss the results in the context of possible helioseismic observations

Epipactis exilis előkerülése a Börzsönyből = Epipactis exilis in the Börzsöny Mts (C Hungary)

2020. augusztus 21-én Börzsönyben a Szén-patak mentén, bükkösben, egy időszakos vízfolyás szélén előkerült hét tő Epipactis exilis. A faj hazánkban igen ritka, fokozottan védett, a börzsönyi az ötödik ismert lelőhelye. Új a hegység flórájára

Modern Teaching Methods in the Training of Basic Surgical Skills

Az NPT módszerrel kapcsolatos kutatásunk célja a közeli kortársoktatás hatékonyságának vizsgálata alapvető sebészeti készségek oktatásakor. Fő hipotézisünk volt, hogy a kortársoktató a kurzus oktatásába szignifikánsan javítja a hallgatók vizsgaeredményeit. Alhipotézisünk volt, hogy az NPT alkalmazása javítja a hallgatók összesített elégedettségét a kurzussal kapcsolatban. A távoktatás hatékonyságának vizsgálata során az alapvető sebészeti ismeretek oktatását elemeztük. Célom volt, hogy objektív módszertan segítségével vizsgáljam a sebészeti alapkészségekhez kapcsolódó távoktatás hatékonyságát. Feltételeztük, hogy egy online tanfolyam megfelelő képzési eszközökkel ugyanolyan hatékony lehet, mint egy „normál” személyes kurzus az alapvető sebészeti ismeretek területén. 5 A kutatómunka eredményei potenciálisan hozzájárulhatnak mind az online, mind a távoktatás feltörekvő területéhez, amely elsősorban a gyakorlati képzések és gyakorlati ismeretek terén jelentenek komoly kihívást az egészségügyi szakemberek képzésében. A bemutatott módszer és a következtetések további kutatásokat kívánnak inspirálni az orvosképzés területén, ezért remélhetőleg további készségalapú kurzusokat is megvizsgálnak digitális környezetben

Prominence Seismology: Wavelet Analysis of Filament Oscillations

The temporal and spatial behavior of a large-amplitude filament oscillation is investigated using wavelet analysis. The extreme-ultraviolet (EUV) images of the phenomenon, which occurred on 2002 October 15, were taken from the EUV Imaging Telescope on board the Solar and Heliospheric Observatory (SOHO). The wavelet spectra, extracted from the intensity data, show that the filament oscillates as a rigid body, with a period of about 2.5-2.6 hr which is almost constant along the filament. The period slowly decreases with time until the filament erupts. No clear sign of the eruption is found in the wavelet spectrum prior to the eruption, that followed the filament oscillation. The axial component of the magnetic field is estimated between 1 and 5 G, which is believed to be reasonable for a polar crown filament of this kind