Search Publications
Meridional flow in the Sun’s convection zone is a single cell in each hemisphere
Gizon, Laurent; Cameron, Robert H.; Liang, Zhi-Chao +4 more
The Sun’s magnetic field is generated by subsurface motions of the convecting plasma. The latitude at which the magnetic field emerges through the solar surface (as sunspots) drifts toward the equator over the course of the 11-year solar cycle. We use helioseismology to infer the meridional flow (in the latitudinal and radial directions) over two …
Particle acceleration by a solar flare termination shock
Krucker, Säm; Chen, Bin; Gary, Dale E. +3 more
Solar flares—the most powerful explosions in the solar system—are also efficient particle accelerators, capable of energizing a large number of charged particles to relativistic speeds. A termination shock is often invoked in the standard model of solar flares as a possible driver for particle acceleration, yet its existence and role have remained…
Destruction of Sun-Grazing Comet C/2011 N3 (SOHO) Within the Low Solar Corona
Schrijver, C. J.; Battams, K.; Brown, J. C. +4 more
Observations of comets in Sun-grazing orbits that survive solar insolation long enough to penetrate into the Sun's inner corona provide information on the solar atmosphere and magnetic field as well as on the makeup of the comet. On 6 July 2011, the Solar Dynamics Observatory (SDO) observed the demise of comet C/2011 N3 (SOHO) within the low solar…
Detection of Emerging Sunspot Regions in the Solar Interior
Zhao, Junwei; Ilonidis, Stathis; Kosovichev, Alexander
Sunspots are regions where strong magnetic fields emerge from the solar interior and where major eruptive events occur. These energetic events can cause power outages, interrupt telecommunication and navigation services, and pose hazards to astronauts. We detected subsurface signatures of emerging sunspot regions before they appeared on the solar …
Variations in the Sun’s Meridional Flow over a Solar Cycle
Hathaway, David H.; Rightmire, Lisa
The Sun’s meridional flow is an axisymmetric flow that is generally directed from its equator toward its poles at the surface. The structure and strength of the meridional flow determine both the strength of the Sun’s polar magnetic field and the intensity of sunspot cycles. We determine the meridional flow speed of magnetic features on the Sun us…
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…
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…
Slipping Magnetic Reconnection in Coronal Loops
Golub, Leon; DeLuca, Edward E.; Narukage, Noriyuki +6 more
Magnetic reconnection of solar coronal loops is the main process that causes solar flares and possibly coronal heating. In the standard model, magnetic field lines break and reconnect instantaneously at places where the field mapping is discontinuous. However, another mode may operate where the magnetic field mapping is continuous but shows steep …
Deflection of the Interstellar Neutral Hydrogen Flow Across the Heliospheric Interface
Bertaux, J. L.; Lallement, R.; Quémerais, E. +3 more
Using an absorption cell, we measured the Doppler shifts of the interstellar hydrogen resonance glow to show the direction of the neutral hydrogen flow as it enters the inner heliosphere. The neutral hydrogen flow is found to be deflected relative to the helium flow by about 4°. The most likely explanation of this deflection is a distortion of the…
Solar Wind Origin in Coronal Funnels
Wilhelm, Klaus; Marsch, Eckart; Wang, Jing-Xiu +4 more
The origin of the solar wind in solar coronal holes has long been unclear. We establish that the solar wind starts flowing out of the corona at heights above the photosphere between 5 megameters and 20 megameters in magnetic funnels. This result is obtained by a correlation of the Doppler-velocity and radiance maps of spectral lines emitted by var…