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The work analytically substantiates the parameters of the surface wave found in numerical modelling of the collision of two oncoming supersonic plasma flows inside a magnetic arc in application to the experiment on the laboratory setup…

等离子体物理 · 物理学 2025-12-11 Sergey A. Koryagin , Mikhail E. Viktorov , Artem V. Korzhimanov , Andrey A. Elyasin

We use 2D numerical simulations and eikonal approximation, to study properties of MHD waves traveling below the solar surface through the magnetic structure of sunspots. We consider a series of magnetostatic models of sunspots of different…

天体物理学 · 物理学 2011-02-11 E. Khomenko , A. Kosovichev , M. Collados , K. Parchevsky , V. Olshevsky

We investigate deviations in the mean phase travel time of acoustic waves preceding the emergence of 46 large active regions observed by the Helioseismic and Magnetic Imager (HMI). In our investigation, we consider two different procedures…

太阳与恒星天体物理 · 物理学 2023-05-03 John Stefan , Alexander Kosovichev

The asteroseismology of rapidly rotating pulsating stars is hindered by our poor knowledge of the effect of the rotation on the oscillation properties. Here we present an asymptotic analysis of high-frequency acoustic modes in rapidly…

太阳与恒星天体物理 · 物理学 2015-05-13 F. Lignieres , B. Georgeot

Observations show the increase of high-frequency wave power near magnetic network cores and active regions in the solar lower atmosphere. This phenomenon can be explained by the interaction of acoustic waves with a magnetic field. We…

天体物理学 · 物理学 2015-05-13 D. Kuridze , T. V. Zaqarashvili , B. M. Shergelashvili1 , S. Poedts

Helioseismic and magnetohydrodynamic waves are abundant in and above sunspots. Through cross-correlating oscillation signals in the photosphere observed by the SDO/HMI, we reconstruct how waves propagate away from virtual wave sources…

太阳与恒星天体物理 · 物理学 2015-08-19 Junwei Zhao , Ruizhu Chen , Thomas Hartlep , Alexander G. Kosovichev

We introduce a new generic model of a deformed Composite Fermion-Fermi Surface (CF-FS) for the Fractional Quantum Hall Effect near $\nu=1/2$ in the presence of a periodic density modulation. Our model permits us to explain the recent…

介观与纳米尺度物理 · 物理学 2007-05-23 Nataliya A. Zimbovskaya , Joseph L. Birman

Acoustic modes of oscillation are affected by stellar activity, however it is unclear how starspots contribute to these changes. Here we investigate the nonmagnetic effects of starspots on global modes with angular degree $\ell \leq 2$ in…

太阳与恒星天体物理 · 物理学 2015-05-20 Emanuele Papini , Aaron C. Birch , Laurent Gizon , Shravan M. Hanasoge

We present a study of the properties of strong 0.8-3.0 Hz quasi-periodic oscillations (QPOs) that occurred during 1997 RXTE observations of the microquasar GRS 1915+105 in the low-hard state. The high count rates allow us to track…

天体物理学 · 物理学 2009-10-31 John A. Tomsick , Philip Kaaret

We explore the effects of spatial locality on the dynamics of random quantum systems subject to a Markovian noise. To this end, we study a model in which the system Hamiltonian and its couplings to the noise are random matrices whose…

量子物理 · 物理学 2024-01-26 Dror Orgad , Vadim Oganesyan , Sarang Gopalakrishnan

Employing Big Bear Solar Observatory (BBSO) deep magnetograms and H${\alpha}$ images in a quiet region and a coronal hole, observed on September 14 and 16, 2004, respectively, we have explored the magnetic flux emergence, disappearance and…

天体物理学 · 物理学 2010-11-11 Jun Zhang , Jun Ma , Haimin Wang

We study the effect of localized sound-speed perturbations on global mode frequencies by applying techniques of global helioseismology on numerical simulations of the solar acoustic wave field. Extending the method of realization noise…

天体物理学 · 物理学 2009-11-13 S. M. Hanasoge , T. P. Larson

Generation of Alfv\'en and slow magneto-acoustic waves in weakly ionized atmospheres by excitation of the charges-only component of the two fluid (charges and neutrals) plasma is shown to be more or less efficient depending on the energy…

太阳与恒星天体物理 · 物理学 2023-06-16 Paul S. Cally

We used long high-quality unresolved (Sun-as-a-star observations) data collected by GOLF and VIRGO instruments on board the ESA/NASA SOHO satellite to investigate the amplitude variation with solar cycle 23 in the high-frequency band (5.7 <…

太阳与恒星天体物理 · 物理学 2015-05-13 R. Simoniello , W. Finsterle , R. A. Garcia , D. Salabert , A. Jimenez

The absorption coefficient for surface acoustic waves in a piezoelectric insulator in contact with a GaAs/AlGaAs heterostructure (with two-dimensional electron mobility $\mu= 1.3\times 10^5 cm^2/V\cdot s)$ at T=4.2K) via a small gap has…

介观与纳米尺度物理 · 物理学 2009-10-31 I. L. Drichko , A. M. Diakonov , A. M. Kreshchuk , T. A. Polyanskaya , I. G. Savel'ev , I. Yu. Smirnov , A. V. Suslov

Taking advantage of the anomalous Hall effect, we electrically probe low-frequency magnetization fluctuations at room temperature in a thin ferromagnetic Pt/Co/AlO$_x$ layer stack with perpendicular magnetic anisotropy. We observe a strong…

介观与纳米尺度物理 · 物理学 2024-02-29 Nadine Nabben , Giacomo Sala , Ulrich Nowak , Matthias Krüger , Sebastian T. B. Goennenwein

The sunspot-associated sources at the frequency of 17 GHz give information on plasma parameters in the regions of magnetic field about B=2000 G at the level of the chromosphere-corona transition region. The observations of short period…

太阳与恒星天体物理 · 物理学 2015-03-19 Vladimir E. Abramov-Maximov , George B. Gelfreikh , Kiyoto Shibasaki

Recurrent and propagating intensity perturbations are frequently observed in extreme ultraviolet (EUV) channels along coronal fan loops above sunspots, and these perturbations are suggested to be slow magnetoacoustic waves. Numerous studies…

太阳与恒星天体物理 · 物理学 2025-02-26 Junwei Zhao , Tongjiang Wang , Ruizhu Chen

The existence of outflow and magnetic field in the inner region of hot accretion flows have been confirmed by observations and numerical magnetohydrodynamic simulations (MHD). We present self-similar solutions for radiation inefficiently…

星系天体物理 · 物理学 2015-06-05 S. Abbassi , A. Mosallanezhad

A time-distance helioseismic technique, similar to the one used by Ilonidis et al (2011), is applied to two independent numerical models of subsurface sound-speed perturbations to determine the spatial resolution and accuracy of phase…

太阳与恒星天体物理 · 物理学 2021-06-02 John T. Stefan , Alexander G. Kosovichev , Andrey M. Stejko