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It has long been known that magnetic plage and sunspots are regions in which the power of acoustic waves is reduced within the photospheric layers. Recent observations now suggest that this suppression of power extends into the low…

Solar and Stellar Astrophysics · Physics 2015-06-19 Rekha Jain , Andrew Gascoyne , Bradley W. Hindman , Benjamin Greer

We present here a continuation of our ongoing project of multiwavelength optical observations aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features that are…

Astrophysics · Physics 2007-05-23 J. Sanz-Forcada , D. Montes , M. J. Fernandez-Figueroa , E. De Castro , M. Cornide

MHD wave propagation inside the Sun's atmosphere is closely related to the magnetic field topology. For example, magnetic fields are able to lower the cutoff frequency for acoustic waves thus allowing waves which would otherwise be trapped…

Solar and Stellar Astrophysics · Physics 2015-05-30 M. Stangalini , D. Del Moro , F. Berrilli , S. M. Jefferies

While the {\it Helioseismic and Magnetic Imager} (HMI) onboard the {\it Solar Dynamics Observatory} (SDO) provides Doppler velocity [$V$], continuum intensity [$I_C$], and line-depth [$Ld$] observations, each of which is sensitive to the…

Solar and Stellar Astrophysics · Physics 2015-09-24 Rachel Howe , Kiran Jain , Richard S. Bogart , Deborah A. Haber , Charles S. Baldner

We present properties of intensity oscillations of a sunspot in the photosphere and chromosphere using G~band and CaIIH filtergrams from Hinode. Intensity power maps as function of magnetic field strength and frequency reveal reduction of…

Solar and Stellar Astrophysics · Physics 2015-02-17 Ankala Raja Bayanna , Shibu K Mathew , Brajesh Kumar , Rohan E Louis , Parameswaran Venkatakrishnan

Probing the solar corona is crucial to study the coronal heating and solar wind acceleration. However, the transient and inhomogeneous solar wind flows carry large-amplitude inherent Alfven waves and turbulence, which make detection more…

In the current analysis, we use spectroscopic observations of the quiet-Sun made by IRIS instrument, and investigate wave propagation. We analyze various spectral lines formed in different atmospheric layers such as the photosphere,…

Solar and Stellar Astrophysics · Physics 2024-03-18 Kartika Sangal , A. K. Srivastava , P. Kayshap , Ding Yuan , E. Scullion

We investigate the trajectories of rigid fibers as they are transported in a pressure-driven flow, at low Reynolds number, in shallow Hele Shaw cells. The transverse confinement and the resulting viscous friction on these elongated objects,…

We report on the co-existence of longitudinal and transverse oscillations in an active filament. On March 15$^{th}$ 2013, a M1.1 class flare was observed in the active region AR 11692. A CME was found to be associated with the flare. {The…

Solar and Stellar Astrophysics · Physics 2016-12-07 V. Pant , R. Mazumder , D. Yuan , D. Banerjee , A. K. Srivastava , Y. Shen

We present the first observations of spatially resolved oscillation sources obtained with the Siberian Radioheliograph (SRH) at 3-6 GHz. We have found significant flux oscillations with periods of about 3, 5 and 13 minutes emitted from…

Solar and Stellar Astrophysics · Physics 2022-10-06 Robert Sych , Alexander Altyntsev

Moreton waves are widely regarded as the chromospheric counterpart of extreme ultraviolet (EUV) waves propagating in the corona. However, direct observational evidence confirming their simultaneous propagation across multiple atmospheric…

Solar and Stellar Astrophysics · Physics 2025-07-22 Yunxue Huang , Qin Feng , Yuhu Miao , Zhining Qu , Ke Yu , Hongfei Liang , Yu Liu , Xinping Zhou

Solar flares involve the sudden release of magnetic energy in the solar corona. Accelerated nonthermal electrons have often been invoked as the primary means for transporting the bulk of the released energy to the lower solar atmosphere.…

Solar and Stellar Astrophysics · Physics 2019-02-20 Sijie Yu , Bin Chen

We use spectropolarimetric observations of the Ca II 8542~\AA\ line, taken from the Swedish 1-m Solar Telescope (SST), in an attempt to recover dynamic activity in a micro-flaring region near a sunspot via inversions. These inversions show…

Solar and Stellar Astrophysics · Physics 2017-08-30 A. Reid , V. Henriques , M. Mathioudakis , J. G. Doyle , T. Ray

We determine the frequencies of solar oscillations covering a wide range of degree (100< l <4000) and frequency (1.5 <\nu<10 mHz) using the ring diagram technique applied to power spectra obtained from MDI (Michelson Doppler Imager) data.…

Astrophysics · Physics 2009-10-31 H. M. Antia , Sarbani Basu

The Atacama Large Millimeter/sub-millimeter Array (ALMA) has provided us with an excellent diagnostic tool for studies of the dynamics of the Solar chromosphere, albeit through a single receiver band at one time presently. Each ALMA band…

Solar and Stellar Astrophysics · Physics 2022-09-14 Juan Camilo Guevara Gómez , Shahin Jafarzadeh , Sven Wedemeyer , Mikolaj Szydlarski

Advanced inversions of high-resolution spectropolarimetric observations of the He I triplet at 1083 nm are used to generate unique maps of the chromospheric magnetic field vector across a sunspot and its superpenumbral canopy. The…

Solar and Stellar Astrophysics · Physics 2015-08-06 T. A. Schad , M. J. Penn , H. Lin , A. Tritschler

Solar inertial modes have the potential to surpass the diagnostic capabilities of acoustic waves in probing the deep interior of the Sun. The fulfillment of this potential requires an accurate identification and characterization of these…

Solar and Stellar Astrophysics · Physics 2025-03-20 Chris S. Hanson , Vivek Menon , Shravan Hanasoge , Katepalli R. Sreenivasan

We present a new multi-pixel high resolution (R >10^7) spectrometer for the Stratospheric Observatory for Far-Infrared Astronomy (SOFIA). The receiver uses 2 x 7-pixel subarrays in orthogonal polarization, each in an hexagonal array around…

The recent launch of the High resolution Coronal imager (Hi-C) provided a unique opportunity to study the EUV corona with unprecedented spatial resolution. We utilize these observations to investigate the properties of low frequency (50-200…

Solar and Stellar Astrophysics · Physics 2013-06-28 R. J. Morton , J. A. McLaughlin

We used spectropolarimetric observations of a sunspot in active region NOAA 11809 in the Ca ii line at 854.2 nm taken with the SpectroPolarimeter for Optical and Infrared Regions (SPINOR) at the Dunn Solar Telescope to infer thermodynamic…

Solar and Stellar Astrophysics · Physics 2018-04-23 Debi Prasad Choudhary , Christian Beck