Search Publications
Empirical Modeling of Radiative versus Magnetic Flux for the Sun-as-a-Star
Nandy, Dibyendu; Martens, Petrus C. H.; Preminger, Dora +1 more
We study the relationship between full-disk solar radiative flux at different wavelengths and average solar photospheric magnetic-flux density, using daily measurements from the Kitt Peak magnetograph and other instruments extending over one or more solar cycles. We use two different statistical methods to determine the underlying nature of these …
Coronal Shocks Associated with Impulsive and Decaying Phases of Solar Flares
Shanmugaraju, A.; Vršnak, B.; Suresh, K. +1 more
We have analyzed a set of 147 metric Type II radio bursts observed by Culgoora radio spectrograph from November 1997 to December 2006. These events were divided into two sets: The first subset contains Type II events that started during the impulsive phase of the associated solar flares and the second subset contains those starting during the deca…
Seeing-Induced Errors in Solar Doppler Velocity Measurements
Sridharan, R.; Sankarasubramanian, K.; Padinhatteeri, Sreejith
Imaging systems based on a narrow-band tunable filter are used to obtain Doppler velocity maps of solar features. These velocity maps are created by taking the difference between the blue- and red-wing intensity images of a chosen spectral line. This method has the inherent assumption that these two images are obtained under identical conditions. …
CME Classification Based on Wavelet Spectra
Raga, A. C.; Blanco-Cano, X.; González-Gómez, D. I.
We study the internal structure of coronal mass ejections (CMEs) using wavelet analysis. We derive wavelet spectra, spatially integrated over regions of interest within LASCO C2 white-light coronographic images. These spectra show an inflection point, which we use to characterize each spectrum. In a diagram of flux vs. spatial scale of the inflect…
Latitudinal and Solar-Cycle Variations of the White-Light Corona from SOHO/LASCO Observations
Fainshtein, V. G.; Kashapova, L. K.; Tsivileva, D. M.
SOHO/LASCO data were used to obtain the latitudinal and radial distributions of the brightness of the K- and F-corona in the period of 1996 - 2007, and their solar-cycle variations were studied. Then an inversion method was employed to obtain the radial distributions of the electron density Ne(R,θ) for various latitude values on the cor…
Automated Coronal-Loop Detection based on Contour Extraction and Contour Classification from the SOHO/EIT Images
Durak, Nurcan; Nasraoui, Olfa; Schmelz, Joan
Arch-shaped coronal loops that are isolated from the background are typically acquired manually from massive online image databases to be used in solar coronal research. The manual search for special coronal loops is not only subject to human mistakes but is also time consuming and tedious. In this study, we propose a completely automated image-re…
An Investigation of the Role of Propagation Effects in the Formation of Drifting Narrowband Type II Fiber Bursts on the Dynamic Spectrum
Afanasiev, A. N.
This paper investigates one of the kinds of fine structure of solar decametric type II radio bursts in the form of drifting narrowband fibers. The appearance of such a structure is customarily explained by the features of the radio emission mechanism in the source, which is formed when the shock wave catches up the previously-generated coronal mas…
In-situ Observations of a Co-rotating Interaction Region at Venus Identified by IPS and STEREO
Barabash, S.; Grande, M.; Dorrian, G. D. +2 more
This paper reports on the first combination of results from in-situ plasma measurements at Venus, using data from Venus Express, and remote sensing data from observations of interplanetary scintillation (IPS). In so doing, we demonstrate the value of combining remote sensing and in-situ techniques for the purpose of investigating interaction betwe…
Influence of the Conversion Layer on the Dispersion Relation of Waves in the Solar Atmosphere
Haberreiter, M.; Finsterle, W.
Observations carried out with the Magneto-Optical Filter at Two Heights (MOTH) experiment show upward-traveling wave packets in magnetic regions with frequencies below the acoustic cut-off. We demonstrate that the frequency dependence of the observed travel times, i.e. the dispersion relation, shows significant differences in magnetic and non-magn…
High-Latitude Inner Solar Wind from Pulsar Radio Sounding Observations
Smirnova, T. V.; Chashei, I. V.; Shishov, V. I.
Radio sounding experiments probing the inner solar wind by polarized pulses of pulsars PSR B0525+21 (J0528+22) and PSR B531+21 (J0534+22) were carried out in June 2005 and June 2007 on the large phased array of the Lebedev Physical Institute at 111 MHz in the period near the minimum of the solar-activity cycle. The lines of sight toward these puls…