Search Publications
Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence
Cranmer, Steven R.; van Ballegooijen, Adriaan A.; Edgar, Richard J.
We present a series of models for the plasma properties along open magnetic flux tubes rooted in solar coronal holes, streamers, and active regions. These models represent the first self-consistent solutions that combine (1) chromospheric heating driven by an empirically guided acoustic wave spectrum; (2) coronal heating from Alfvén waves that hav…
Solar and interplanetary sources of major geomagnetic storms (Dst <= -100 nT) during 1996-2005
Thompson, B. J.; Webb, D. F.; Zhukov, A. N. +9 more
We present the results of an investigation of the sequence of events from the Sun to the Earth that ultimately led to the 88 major geomagnetic storms (defined by minimum Dst ≤ -100 nT) that occurred during 1996-2005. The results are achieved through cooperative efforts that originated at the Living with a Star (LWS) Coordinated Data-Analysis Works…
A Characteristic Magnetic Field Pattern Associated with All Major Solar Flares and Its Use in Flare Forecasting
Schrijver, Carolus J.
Solar flares result from some electromagnetic instability that occurs within regions of relatively strong magnetic field in the Sun's atmosphere. The processes that enable and trigger these flares remain topics of intense study and debate. I analyze observations of 289 X- and M-class flares and over 2500 active region magnetograms to discover (1) …
On the Magnetic Flux Budget in Low-Corona Magnetic Reconnection and Interplanetary Coronal Mass Ejections
Qiu, Jiong; Hu, Qiang; Howard, Timothy A. +1 more
We present the first quantitative comparison between the total magnetic reconnection flux in the low corona in the wake of coronal mass ejections (CMEs) and the magnetic flux in magnetic clouds (MCs) that reach 1 AU 2-3 days after CME onset. The total reconnection flux is measured from flare ribbons, and the MC flux is computed using in situ obser…
Tracking Solar Gravity Modes: The Dynamics of the Solar Core
García, Rafael A.; Turck-Chièze, Sylvaine; Mathur, Savita +5 more
Solar gravity modes have been actively sought because they directly probe the solar core (below 0.2 solar radius), but they have not been conclusively detected in the Sun because of their small surface amplitudes. Using data from the Global Oscillation at Low Frequency instrument, we detected a periodic structure in agreement with the period separ…
Reconstruction of solar total irradiance since 1700 from the surface magnetic flux
Solanki, S. K.; Krivova, N. A.; Balmaceda, L.
Context: Total solar irradiance changes by about 0.1% between solar activity maximum and minimum. Accurate measurements of this quantity are only available since 1978 and do not provide information on longer-term secular trends.
Aims: In order to reliably evaluate the Sun's role in recent global climate change, longer time series are, however,…
Coronal ``Wave'': Magnetic Footprint of a Coronal Mass Ejection?
Harra, Louise K.; Attrill, Gemma D. R.; van Driel-Gesztelyi, Lidia +1 more
We investigate the properties of two ``classical'' EUV Imaging Telescope (EIT) coronal waves. The two source regions of the associated coronal mass ejections (CMEs) possess opposite helicities, and the coronal waves display rotations in opposite senses. We observe deep core dimmings near the flare site and also widespread diffuse dimming, accompan…
Continuous Plasma Outflows from the Edge of a Solar Active Region as a Possible Source of Solar Wind
Golub, Leon; DeLuca, Edward E.; Harra, Louise K. +18 more
The Sun continuously expels a huge amount of ionized material into interplanetary space as the solar wind. Despite its influence on the heliospheric environment, the origin of the solar wind has yet to be well identified. In this paper, we report Hinode X-ray Telescope observations of a solar active region. At the edge of the active region, locate…
Present and Future Observing Trends in Atmospheric Magnetoseismology
Erdélyi, R.; Banerjee, D.; O'Shea, E. +1 more
With modern imaging and spectral instruments observing in the visible, EUV, X-ray, and radio wavelengths, the detection of oscillations in the solar outer atmosphere has become a routine event. These oscillations are considered to be the signatures of a wave phenomenon and are generally interpreted in terms of magnetohydrodynamic (MHD) waves. With…
Coronal Pseudostreamers
Sheeley, N. R., Jr.; Wang, Y. -M.; Rich, N. B.
In a recent study of the 2006 solar eclipse, we noted that there are two kinds of coronal streamers: ``helmet streamers,'' which separate coronal holes of opposite magnetic polarity, and ``pseudostreamers,'' which overlie twin loop arcades and separate holes of the same polarity. It is well known that the heliospheric plasma and current sheets rep…