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We investigate the decayless regime of coronal kink oscillations recently discovered in the Solar Dynamics Observatory (SDO)/AIA data. In contrast to decaying kink oscillations that are excited by impulsive dynamical processes, this type of…

Solar and Stellar Astrophysics · Physics 2015-11-18 S. A. Anfinogentov , V. M. Nakariakov , G. Nisticò

The subject of this study is oscillations in the lower atmosphere in coronal-hole regions, where the conditions are favorable for propagation between the atmospheric layers. Based on spectroscopic observations in photospheric and…

Solar and Stellar Astrophysics · Physics 2021-12-22 Andrei Chelpanov , Nikolai Kobanov , Maksim Chelpanov , Aleksandr Kiselev

In this paper, we address the controversy regarding the recent extended solar minimum as seen in helioseismic low- and intermediate-degree mode frequencies: studies from different instruments identify different epochs of seismic minima.…

Solar and Stellar Astrophysics · Physics 2011-09-01 Kiran Jain , S. C. Tripathy , F. Hill

We have analyzed H-alpha intensity images obtained at a 1 minute cadence with the Global Oscillation Network Group (GONG) system to investigate the properties of oscillations in the 0-8 mHz frequency band at the location and time of strong…

Solar and Stellar Astrophysics · Physics 2018-03-08 Teresa Monsue , Frank Hill , Keivan G. Stassun

We investigate the variation of high-degree mode frequencies as a local response to the active regions in two different phases of the solar activity cycle. We find that the correlation between frequency shifts and the surface magnetic…

Solar and Stellar Astrophysics · Physics 2015-05-13 S. C. Tripathy , K. Jain , F. Hill

We search for indications of waves in the 25-2000 MHz radio spectrum of the 1 August 2010 event (SOL2010-08-01T08:57:00L075C013), where fast propagating waves in the solar corona with the periods of 181, 69, and 40 seconds were detected in…

Solar and Stellar Astrophysics · Physics 2016-12-14 M. Karlicky , J. Rybak

We propose a method for diagnosing the physical conditions in the solar atmosphere using an increase in oscillation amplitudes resulting from minuscule solar flares. As an example, we consider a B2 flare, which caused a sharp short-lived…

Solar and Stellar Astrophysics · Physics 2022-01-05 Andrei Chelpanov , Nikolai Kobanov

Sunspots host various oscillations and wave phenomena like umbral flashes, umbral oscillations, running penumbral waves, and coronal waves. All fan loops rooted in sunspot umbra constantly show a 3-min period propagating slow…

Solar and Stellar Astrophysics · Physics 2023-08-22 Ananya Rawat , Girjesh R. Gupta

Below the acoustic cut-off frequency, oscillations are trapped within the solar interior and become resonant. However, signatures of oscillations persist above the acoustic cut-off frequency, and these travelling waves are known as…

Solar and Stellar Astrophysics · Physics 2022-03-30 K. Kosak , R. Kiefer , A. M. Broomhall

The frequencies of solar oscillations are known to change with solar activity. We use Principal Component Analysis to examine these changes with high precision. In addition to the well-documented changes in solar normal mode oscillations…

Astrophysics · Physics 2009-11-13 Charles S. Baldner , Sarbani Basu

Recent observations show a variety of oscillation modes in the corona. Early non-imaging observations in radio wavelengths showed a number of fast-period oscillations in the order of seconds, which have been interpreted as fast sausage mode…

Astrophysics · Physics 2007-05-23 Markus J. Aschwanden

In this work, we studied oscillation parameters in faculae above magnetic knots and in the adjacent to them areas. Using SDO data we analysed oscillations in magnetic strength, Doppler velocity, and intensity signals for the lower…

Solar and Stellar Astrophysics · Physics 2016-08-17 Andrei A. Chelpanov , Nikolai I. Kobanov , Dmitry Y. Kolobov

We investigate the spatial and temporal variations of the high-degree mode frequencies calculated over localized regions of the Sun during the extended minimum phase between solar cycles 23 and 24. The frequency shifts measured relative to…

Solar and Stellar Astrophysics · Physics 2015-06-11 S. C. Tripathy , K. Jain , Frank Hill

An analysis of line-of-sight velocity oscillation in nine solar faculae was undertaken with the aim of studying of phase relations between chromosphere (He i 10830 A line) and photosphere (Si i 10827 A line) five-minute oscillations. We…

Solar and Stellar Astrophysics · Physics 2015-05-30 N. I. Kobanov , A. S. Kustov , S. A. Chupin , V. A. Pulyaev

Decayless kink oscillations are omnipresent in the solar atmosphere and a viable candidate for coronal heating. Though there have been extensive studies of decayless oscillations in coronal loops with a few hundred Mm lengths, the…

The minimum of solar cycle 24 is significantly different from most other minima in terms of its duration as well as its abnormally low levels of activity. Using available helioseismic data that cover epochs from the minimum of cycle 23 to…

Solar and Stellar Astrophysics · Physics 2015-05-19 H. M. Antia , Sarbani Basu

Spicule oscillations involve high-frequency components with a typical period approximately corresponding to $40-50$ s. The typical time scale of the photospheric oscillation is a few minutes, and thus, the origin of this high-frequency…

Solar and Stellar Astrophysics · Physics 2018-02-28 Munehito Shoda , Takaaki Yokoyama

Context. Recent observations of decayless transverse oscillations have shown two branches in the relationship between periods and loop lengths. One is a linear relationship, interpreted as a standing mode. The other shows almost no…

Solar and Stellar Astrophysics · Physics 2024-10-09 Daye Lim , Tom Van Doorsselaere , Valery M. Nakariakov , Dmitrii Y. Kolotkov , Yuhang Gao , David Berghmans

We studied oscillations related to flare SOL2012-09-21T02:19 in the transition region and chromosphere based on Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Solar Dynamics Observatory (SDO) data, as well as data from a…

Solar and Stellar Astrophysics · Physics 2019-05-29 Nikolai Kobanov , Andrei Chelpanov

Recent observations have revealed the ubiquitous presence of magnetohydrodynamic (MHD) waves and oscillations in the solar corona. The aim of this review is to present recent progress in the observational study of four types of wave (or…

Solar and Stellar Astrophysics · Physics 2018-04-02 Tongjiang Wang