Search Publications
Detection of Equatorward Meridional Flow and Evidence of Double-cell Meridional Circulation inside the Sun
Kosovichev, A. G.; Zhao, Junwei; Duvall, T. L., Jr. +2 more
Meridional flow in the solar interior plays an important role in redistributing angular momentum and transporting magnetic flux inside the Sun. Although it has long been recognized that the meridional flow is predominantly poleward at the Sun's surface and in its shallow interior, the location of the equatorward return flow and the meridional flow…
Direct Evidence for a Fast Coronal Mass Ejection Driven by the Prior Formation and Subsequent Destabilization of a Magnetic Flux Rope
Patsourakos, S.; Stenborg, G.; Vourlidas, A.
Magnetic flux ropes play a central role in the physics of coronal mass ejections (CMEs). Although a flux-rope topology is inferred for the majority of coronagraphic observations of CMEs, a heated debate rages on whether the flux ropes pre-exist or whether they are formed on-the-fly during the eruption. Here, we present a detailed analysis of extre…
Longitudinal and Radial Dependence of Solar Energetic Particle Peak Intensities: STEREO, ACE, SOHO, GOES, and MESSENGER Observations
Lario, D.; Roelof, E. C.; Ho, G. C. +5 more
Simultaneous measurements of solar energetic particle (SEP) events by two or more of the spacecraft located near 1 AU during the rising phase of solar cycle 24 (i.e., STEREO-A, STEREO-B, and near-Earth spacecraft such as ACE, SOHO, and GOES) are used to determine the longitudinal dependence of 71-112 keV electron, 0.7-3 MeV electron, 15-40 MeV pro…
Implications of Mass and Energy Loss due to Coronal Mass Ejections on Magnetically Active Stars
Drake, Jeremy J.; Gopalswamy, Nat; Yashiro, Seiji +1 more
Analysis of a database of solar coronal mass ejections (CMEs) and associated flares over the period 1996-2007 finds well-behaved power-law relationships between the 1-8 Å flare X-ray fluence and CME mass and kinetic energy. We extrapolate these relationships to lower and higher flare energies to estimate the mass and energy loss due to CMEs from s…
The Driver of Coronal Mass Ejections in the Low Corona: A Flux Rope
Liu, Y.; Cheng, X.; Ding, M. D. +2 more
Recent Solar Dynamic Observatory observations reveal that coronal mass ejections (CMEs) consist of a multi-temperature structure: a hot flux rope and a cool leading front (LF). The flux rope first appears as a twisted hot channel in the Atmospheric Imaging Assembly (AIA) 94 Å and 131 Å passbands. The twisted hot channel initially lies along the po…
Comparison of Kepler Photometric Variability with the Sun on Different Timescales
Basri, Gibor; Walkowicz, Lucianne M.; Reiners, Ansgar
We utilize Kepler data to study the precision differential photometric variability of solar-type and cooler stars at different timescales, ranging from half an hour to three months. We define a diagnostic that characterizes the median differential intensity change between data bins of a given timescale. We apply the same diagnostics to Solar and H…
Global Helioseismic Evidence for a Deeply Penetrating Solar Meridional Flow Consisting of Multiple Flow Cells
Roth, M.; Schad, A.; Timmer, J.
We use a novel global helioseismic analysis method to infer the meridional flow in the deep Solar interior. The method is based on the perturbation of eigenfunctions of Solar p modes due to meridional flow. We apply this method to time series obtained from Dopplergrams measured by the Michelson Doppler Imager aboard the Solar and Heliospheric Obse…
Forecasting a Coronal Mass Ejection's Altered Trajectory: ForeCAT
Kay, C.; Opher, M.; Evans, R. M.
To predict whether a coronal mass ejection (CME) will impact Earth, the effects of the background on the CME's trajectory must be taken into account. We develop a model, ForeCAT (Forecasting a CME's Altered Trajectory), of CME deflection due to magnetic forces. ForeCAT includes CME expansion, a three-part propagation model, and the effects of drag…
Asymmetric Solar Polar Field Reversals
Svalgaard, Leif; Kamide, Yohsuke
The solar polar fields reverse because magnetic flux from decaying sunspots moves toward the poles, with a preponderance of flux from the trailing spots. If there is a strong asymmetry, in the sense that most activity is in the northern hemisphere, then that excess flux will move toward the north pole and reverse that pole first. If there is more …
A Global Wave-driven Magnetohydrodynamic Solar Model with a Unified Treatment of Open and Closed Magnetic Field Topologies
Gombosi, T. I.; Landi, E.; Jin, M. +3 more
We describe, analyze, and validate the recently developed Alfvén Wave Solar Model, a three-dimensional global model starting from the top of the chromosphere and extending into interplanetary space (out to 1-2 AU). This model solves the extended, two-temperature magnetohydrodynamics equations coupled to a wave kinetic equation for low-frequency Al…