Search Publications
Detection of Solar Rotational Variability in the Large Yield RAdiometer (LYRA) 190 - 222 nm Spectral Band
Schmutz, W.; Rozanov, E.; Shapiro, A. I. +4 more
We analyze the variability of the spectral solar irradiance during the period from 7 January 2010 until 20 January 2010 as measured by the Herzberg channel (190 - 222 nm) of the Large Yield RAdiometer (LYRA) onboard PROBA2. In this period of time, observations by the LYRA nominal unit experienced degradation and the signal produced by the Herzberg…
Solar Activity and Deep Convection Modeling
Khodachenko, M. L.; Arkhypov, O. V.; Antonov, O. V.
We suggest from synoptic charts of radial magnetic field and intensities of spectral lines (Fe I, He II, and Fe IX/X) over Carrington rotations 1942 - 2050 that deep convective layers control the pattern of large-scale solar activity. A new result is a Kolmogorov-type energy spectrum of the longitudinal variations of solar activity. This spectrum …
The Sub-surface Structure of a Large Sample of Active Regions
Bogart, R. S.; Basu, S.; Baldner, C. S.
We employ ring-diagram analysis to study the sub-surface thermal structure of active regions. We present results using a large number of active regions over the course of Solar Cycle 23. We present both traditional inversions of ring-diagram frequency differences, with a total sample size of 264, and a statistical study using Principal Component A…
Using an Ellipsoid Model to Track and Predict the Evolution and Propagation of Coronal Mass Ejections
Cattell, C.; Schreiner, S.; Kersten, K. +1 more
We present a method for tracking and predicting the propagation and evolution of coronal mass ejections (CMEs) using the imagers on the STEREO and SOHO satellites. By empirically modeling the material between the inner core and leading edge of a CME as an expanding, outward propagating ellipsoid, we track its evolution in three-dimensional space. …
Latest Results Found with Ring-Diagram Analysis
Howe, R.; Hill, F.; Rabello-Soares, M. C. +9 more
Ring-diagram analysis is a helioseismic tool useful for studying the near-surface layers of the Sun. It has been employed to study near-surface shear, meridional circulation, flows around sunspots, and thermal structure beneath active regions. We review recent results obtained using ring-diagram analysis, state some of the more important outstandi…
Photospheric Stratification of a Central Umbral Dot Using Stokes Profiles Recorded by Hinode: A Different Single-Case Study
Hamedivafa, H.
We aim to study the physical nature of a central umbral dot (UD) close to disk center by analyzing full-Stokes spectra of the two Fe I lines at 630 nm recorded by the spectropolarimeter on Hinode. Thermal and magnetic properties of the UD were directly inferred from Stokes profiles. Then, we applied the inversion code SIR to retrieve a single-comp…
Equatorwards Expansion of Unperturbed, High-Latitude Fast Solar Wind
Breen, A. R.; Bisi, M. M.; Fallows, R. A. +1 more
We use dual-site radio observations of interplanetary scintillation (IPS) with extremely long baselines (ELB) to examine meridional flow characteristics of the ambient fast solar wind at plane-of-sky heliocentric distances of 24 - 85 solar radii (R⊙). Our results demonstrate an equatorwards deviation of 3 - 4∘ in the bulk fas…
Instrumental and Observational Artifacts in Quiet Sun Magnetic Flux Cancellation Functions
Pietarila, A.; Pietarila Graham, J.
Under the assumption that the photospheric quiet Sun magnetic field is turbulent, the cancellation function has previously been used to estimate the true, resolution-independent mean, unsigned vertical flux «|Bz|»true. We show that the presence of network elements, noise, and seeing complicate the measurement of accurate canc…
Comparison of Line-of-Sight Magnetograms Taken by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager and Solar and Heliospheric Observatory/Michelson Doppler Imager
Liu, Y.; Sun, X.; Hoeksema, J. T. +7 more
We compare line-of-sight magnetograms from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) and the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO). The line-of-sight magnetic signal inferred from the calibrated MDI data is greater than that derived from the HMI data by a …
The Large Longitudinal Spread of Solar Energetic Particles During the 17 January 2010 Solar Event
Gómez-Herrero, R.; Dresing, N.; Heber, B. +3 more
We investigate multi-spacecraft observations of the 17 January 2010 solar energetic particle event. Energetic electrons and protons have been observed over a remarkable large longitudinal range at the two STEREO spacecraft and SOHO, suggesting a longitudinal spread of nearly 360 degrees at 1 AU. The flaring active region, which was on the backside…