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Photospheric and heliospheric magnetic fields
Schrijver, Carolus J.; De Rosa, Marc L.
The magnetic field in the heliosphere evolves in response to the photospheric field at its base. This evolution, together with the rotation of the Sun, drives space weather through the continually changing conditions of the solar wind and the magnetic field embedded within it. We combine observations and simulations to investigate the sources of t…
Observations of Rotating Sunspots from TRACE
Schrijver, C. J.; Shine, R. A.; Title, A. M. +5 more
Recent observations from TRACE in the photospheric white-light channel have shown sunspots that rotate up to 200° about their umbral centre over a period of 3-5 days. The corresponding loops in the coronal fan are often seen to twist and can erupt as flares. In an ongoing study, seven cases of rotating sunspots have been identified, two of which c…
Weak-Field Magnetogram Calibration using Advanced Stokes Polarimeter Flux Density Maps - II. SOHO/MDI Full-Disk Mode Calibration
Lites, B. W.; Berger, T. E.
Cotemporal Ni i 676.8 nm full-disk magnetograms from the Michelson Doppler Interferometer (MDI) instrument on SOHO and the Advanced Stokes Polarimeter (ASP) are quantitatively compared using observations of active region AR 8218, a large negative polarity sunspot group observed at S20 W22 on 13 May 1998. MDI produces flux density estimates based o…
A Search for CMEs Associated with Big Flares
Andrews, M. D.
The relationship between flares and coronal mass ejections (CMEs) remains a topic of active research. This paper considers a complete set of 311 M- and X-class GOES soft X-ray flares observed during the years 1996-1999. The durations of these flares have been determined as part of this study. Possible CME candidates for the 229 flares with good LA…
SUMER spectral observations of post-flare supra-arcade inflows
Innes, D. E.; McKenzie, D. E.; Wang, Tongjiang
On 21 April 2002 a large eruptive flare on the west limb of the Sun developed a bright, very dynamic, post-flare arcade. In TRACE 195 Å images, a series of dark, sunward moving flows were seen against the bright extreme ultraviolet (EUV) arcade. SUMER obtained a series of spectra of the dark EUV flows in the lines C ii, Fe xii, and Fe xxi at a fix…
Observations of 1000 km s−1 Doppler shifts in 107 K solar flare supra-arcade
Innes, D. E.; McKenzie, D. E.; Wang, Tongjiang
An X1.5 flare on the west limb of the Sun on 21 April 2002 developed a large supra-arcade about 30 min after flare onset. The growth of the supra-arcade can be followed in both TRACE 195 Å images and SUMER spectra. Its growth seems to be associated with dark (in TRACE images), sunward moving channels that descend onto the arcade from above. SUMER …
The Siberian Solar Radio Telescope: the current state of the instrument, observations, and data
Grechnev, V. V.; Uralov, A. M.; Altyntsev, A. T. +8 more
The Siberian Solar Radio Telescope (SSRT) is one of the world's largest solar radio heliographs. It commenced operation in 1983, and since then has undergone several upgrades. The operating frequency of the SSRT is 5.7 GHz. Since 1992 the instrument has had the capability to make one-dimensional scans with a high time resolution of 56 ms and an an…
How are Emerging Flux, Flares and CMEs Related to Magnetic Polarity Imbalance in Midi Data?
Mandrini, C. H.; Démoulin, P.; Green, L. M. +1 more
In order to understand whether major flares or coronal mass ejections (CMEs) can be related to changes in the longitudinal photospheric magnetic field, we study 4 young active regions during seven days of their disk passage. This time period precludes any biases which may be introduced in studies that look at the field evolution during the short-t…
On the kinematic evolution of flare-associated cmes
Moon, Y. -J.; Shanmugaraju, A.; Dryer, M. +1 more
We report a common tendency of the kinematic evolution of three flare-associated coronal mass ejections (CMEs). Their kinematic evolutions are examined using well-observed data (eruptive filaments, X-ray structures, and prominences) very close to the solar surface as well as SOHO/LASCO C2-C3 data. Their height-time data are fitted using three anal…
Statistical Flux Tube Properties of 3D Magnetic Carpet Fields
Priest, E. R.; Parnell, C. E.; Mackay, D. H. +1 more
The quiet-Sun photosphere consists of numerous magnetic flux fragments of both polarities that evolve with granular and supergranular flow fields. These concentrations give rise to a web of intermingled magnetic flux tubes which characterise the coronal magnetic field. Here, the nature of these flux tubes is studied. The photosphere is taken to be…