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A Comparison of Solar Cycle Variations in the Equatorial Rotation Rates of the Sun's Subsurface, Surface, Corona, and Sunspot Groups
Javaraiah, J.
Using the Solar Optical Observing Network (SOON) sunspot-group data for the period 1985 - 2010, the variations in the annual mean equatorial-rotation rates of the sunspot groups are determined and compared with the known variations in the solar equatorial-rotation rates determined from the following data: i) the plasma rotation rates at 0.94R…
Sun-as-a-Star Observation of Flares in Lyman α by the PROBA2/LYRA Radiometer
Kretzschmar, M.; Dammasch, I. E.; Dominique, M.
There are very few reports of flare signatures in the solar irradiance at H I Lyman α at 121.5 nm, i.e. the strongest line of the solar spectrum. The LYRA radiometer onboard PROBA2 has observed several flares for which unambiguous signatures have been found in its Lyman-α channel. Here we present a brief overview of these observations followed by …
What Have We Learned from Helioseismology, What Have We Really Learned, and What Do We Aspire to Learn?
Gough, Douglas
Helioseismology has been widely acclaimed as having been a great success: it appears to have answered nearly all the questions that we originally asked, some with unexpectedly high precision. We have learned how the sound speed and matter density vary throughout almost all of the solar interior - something which not so very long ago was generally …
The Extended Solar Cycle Tracked High into the Corona
Tappin, S. J.; Altrock, R. C.
We present observations of the extended solar cycle activity in white-light coronagraphs, and compare them with the more familiar features seen in the Fe XIV green-line corona. We show that the coronal activity zones seen in the emission corona can be tracked high into the corona. The peak latitude of the activity, which occurs near solar maximum,…
Formation of a White-Light Jet Within a Quadrupolar Magnetic Configuration
Filippov, Boris; Tavabi, Ehsan; Koutchmy, Serge
We analyze multi-wavelength and multi-viewpoint observations of a large-scale event viewed on 7 April 2011, originating from an active-region complex. The activity leads to a white-light jet being formed in the outer corona. The topology and evolution of the coronal structures were imaged in high resolution using the Atmospheric Imaging Assembly (…
On the Possibility to Diagnose the Non-Maxwellian κ-Distributions from the Hinode/EIS EUV Spectra
Dzifčáková, E.; Dudík, J.; Mackovjak, Š.
We investigate the possibility to diagnose the κ-distributions from the EUV spectra observed by the Hinode/EIS spectrometer. Observable lines of the most abundant elements except Fe are considered. Synthetic spectra for the κ-distributions with κ=2 - 10 and the Maxwellian distribution were calculated for a range of temperatures and electron densit…
Nature of Quiet Sun Oscillations Using Data from the Hinode, TRACE, and SOHO Spacecraft
Doyle, J. G.; Madjarska, M. S.; Gupta, G. R. +2 more
We study the nature of quiet-Sun oscillations using multi-wavelength observations from TRACE, Hinode, and SOHO. The aim is to investigate the existence of propagating waves in the solar chromosphere and the transition region by analyzing the statistical distribution of power in different locations, e.g. in bright magnetic (network), bright non-mag…
Comparison of Cone Model Parameters for Halo Coronal Mass Ejections
Moon, Y. -J.; Lee, Kyoung-Sun; Jang, Soojeong +2 more
Halo coronal mass ejections (HCMEs) are a major cause of geomagnetic storms, hence their three-dimensional structures are important for space weather. We compare three cone models: an elliptical-cone model, an ice-cream-cone model, and an asymmetric-cone model. These models allow us to determine three-dimensional parameters of HCMEs such as radial…
Increasing the Fine Structure Visibility of the Hinode SOT Ca II H Filtergrams
Koutchmy, S.; Tavabi, E.; Ajabshirizadeh, A.
We present an image processing technique, the improved OMC filter (also called Madmax), which selects maxima of convexities of intensity modulations of an image. The filter computes second derivatives of the image in multiple directions around each pixel. It is shown to be efficient for pattern recognition, and bright hair-like or small anisotropi…
Radial Speed Evolution of Interplanetary Coronal Mass Ejections During Solar Cycle 23
Tokumaru, M.; Fujiki, K.; Iju, T.
We report radial-speed evolution of interplanetary coronal mass ejections (ICMEs) detected by the Large Angle and Spectrometric Coronagraph onboard the Solar and Heliospheric Observatory (SOHO/LASCO), interplanetary scintillation (IPS) at 327 MHz, and in-situ observations. We analyze solar-wind disturbance factor (g-value) data derived from IPS ob…