Search Publications
High-Resolution Mapping of Flows in the Solar Interior: Fully Consistent OLA Inversion of Helioseismic Travel Times
Birch, A. C.; Gizon, L.; Jackiewicz, J.
To recover the flow information encoded in travel-time data of time - distance helioseismology, accurate forward modeling and a robust inversion of the travel times are required. We accomplish this using three-dimensional finite-frequency travel-time sensitivity kernels for flows along with a (2+1)-dimensional (2+1D) optimally localized averaging …
Magnetic Causes of the Eruption of a Quiescent Filament
Golub, L.; Bommier, V.; Schmieder, B. +5 more
During the JOP178 campaign in August 2006, we observed the disappearance of our target, a large quiescent filament located at S25°, after an observation time of three days (24 August to 26 August). Multi-wavelength instruments were operating: THEMIS/MTR ("MulTi-Raies") vector magnetograph, TRACE ("Transition Region and Coronal Explorer") at 171 Å …
Dynamics of Sunspot Light Bridges as Revealed by High-Resolution Images from Hinode
Venkatakrishnan, P.; Mathew, Shibu K.; Louis, Rohan E. +1 more
We present G-band and Ca II H filtergrams of two sunspot light bridges in NOAA AR 10953 taken from the 50-cm Solar Optical Telescope onboard the Japanese space satellite Hinode on 1 May 2007. The two light bridges differ in structure, with one of them resembling the filamentary penumbra and the other possessing a dark central lane running along th…
The Radiometric and Pointing Calibration of SECCHI COR1 on STEREO
Thompson, W. T.; Reginald, N. L.
COR1 is the innermost coronagraph of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument suite aboard the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft. The paired COR1 telescopes observe the white-light K-corona from 1.4 to 4 solar radii in a waveband 22.5 nm wide centered on the Hα line at 656 n…
On the Relationship between Flux Emergence and CME Initiation
Zhang, Hongqi; Zhang, Mei; Zhang, Yin
We present in this paper a statistical study aimed at understanding the possible relationship between surface magnetic field variation and CME initiation. The three samples studied comprise 189 CME-source regions, 46 active regions, and 15 newly emerging active regions. Both large-scale and small-scale variations of longitudinal magnetic fields of…
Total Solar Irradiance Measurement and Modelling during Cycle 23
Mekaoui, S.; Dewitte, S.
During solar cycle 23, which is now close to its end, variations of the total solar irradiance were measured by six different instruments, providing four independent time series of the irradiance variation over the complete solar cycle. A new composite time series constructed using five of these six instruments provides unprecedented instrument st…
Multiscale Analysis of Active Region Evolution
Maguire, K.; Gallagher, P. T.; Young, C. A. +4 more
Flows in the photosphere of solar active regions are turbulent in nature. Because magnetic fields are frozen into the plasma on the solar surface, magnetograms can be used to investigate the processes responsible for structuring active regions. Here, a continuous wavelet technique is developed, analyzed, and used to investigate the multiscale stru…
Mechanics of Seismic Emission from Solar Flares
Lindsey, C.; Donea, A. -C.
Instances of seismic transients emitted into the solar interior in the impulsive phases of some solar flares offer a promising diagnostic tool, both for understanding the physics of solar flares and for the general development of local helioseismology. Among the prospective contributors to flare acoustic emission that have been considered are: i) …
The Recovery of CME-Related Dimmings and the ICME's Enduring Magnetic Connection to the Sun
Zhukov, A. N.; Mandrini, C. H.; van Driel-Gesztelyi, L. +5 more
It is generally accepted that transient coronal holes (TCHs, dimmings) correspond to the magnetic footpoints of CMEs that remain rooted in the Sun as the CME expands out into the interplanetary space. However, the observation that the average intensity of the 12 May 1997 dimmings recover to their pre-eruption intensity in SOHO/EIT data within 48 h…
Probing the Subsurface Structures of Active Regions with Ring-Diagram Analysis
Basu, Sarbani; Antia, H. M.; Bogart, Richard S. +1 more
We analyze the variations in the near-surface profiles of sound speed and adiabatic constant between active regions and neighboring quiet-Sun areas using the technique of ring-diagram analysis and inversions of the frequency differences between the regions. This approach minimizes the systematic observational effects on the fitted spectral model p…