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Acoustic-Power Maps of Solar Active Regions with Direction Filters and Phase-Velocity Filters
Liang, Zhi-Chao; Chou, Dean-Yi; Sun, Ming-Tsung +1 more
We study the properties of power maps of solar acoustic waves filtered with direction filters and phase-velocity filters. A direction filter is used to isolate acoustic waves propagating in a narrow range of directions. The acoustic-power map of the waves filtered with a direction filter shows extended reduced-power features behind magnetic region…
Radial Evolution of Well-Observed Slow CMEs in the Distance Range 2 - 30 R ⊙
Moon, Y. -J.; Shanmugaraju, A.; Vrsnak, Bojan +1 more
We performed a detailed analysis of 27 slow coronal mass ejections (CMEs) whose heights were measured in at least 30 coronagraphic images and were characterized by a high quality index (≥4). Our primary aim was to study the radial evolution of these CMEs and their properties in the range 2 - 30 solar radii. The instantaneous speeds of CMEs were ca…
3D Coronal Structures and Magnetic Field During the Total Solar Eclipse of 29 March 2006
Druckmüller, M.; Hamid, R. H.; Ambrož, P. +1 more
The good quality of the observing sequence of about 60 photographs of the white-light corona taken during the total solar eclipse observations on 29 March 2006, in Al Sallum, Egypt, enable us to use a new method of image processing for enhancement of the fine structure of coronal phenomena. We present selected magnetic-field lines derived for diff…
Formation Mechanism of Soft X-Ray Transient Trans-Equatorial Loop System
Masuda, Satoshi; Yokoyama, Masaki
The Soft X-ray Telescope (SXT) onboard Yohkoh often observed large-scale coronal loops connecting two active regions situated in opposite hemispheres. These are the trans-equatorial loop systems (TLSs). The formation mechanism of TLSs is not yet known. We analyzed a TLS observed simultaneously with Yohkoh/SXT and a coronagraph (SOHO/LASCO-C1). SOH…
Cross-Calibration of SMART-1 XSM with GOES and RHESSI
Väänänen, Mikko; Alha, Lauri; Huovelin, Juhani
A number of X-ray instruments have been active in observing the solar coronal X-ray radiation this decade. We have compared XSM observations with simultaneous GOES and RHESSI observations. We present flux calibrations for all instruments and compare XSM and GOES total emission measures (TEM) and temperatures (T).
Helioseismic Travel-Time Definitions and Sensitivity to Horizontal Flows Obtained from Simulations of Solar Convection
Birch, Aaron C.; Couvidat, Sébastien
We study the sensitivity of wave travel times to steady and spatially homogeneous horizontal flows added to a realistic simulation of the solar convection performed by Robert F. Stein, Ake Nordlund, Dali Georgobiani, and David Benson. Three commonly used definitions of travel times are compared. We show that the relationship between travel-time di…
Relative Velocities and Linewidths in a Coronal Hole and Outside
Raju, K. P.
Relative Doppler velocities and spectral linewidths in a coronal hole and in the quiet Sun region outside have been obtained from Solar and Heliospheric Observatory (SOHO)/Coronal Diagnostic Spectrometer (CDS) observations. Five strong emission lines in the CDS wavelength range (namely, O III 599 Å, O V 630 Å, Ne VI 562.8 Å, He II 304 Å, and Mg IX…
Magnetic Field Elements at High Latitude: Lifetime and Rotation Rate
Liu, Y.; Zhao, J.
Using one-minute cadence time-series full disk magnetograms taken by the SOHO/MDI, we have studied the magnetic field elements at high latitude (poleward of 65° in latitude). It is found that an average lifetime of the magnetic field elements is 16.5 h during solar minimum, much longer than that during solar maximum (7.3 h). During solar minimum, …
Post-Eruptive Arcade Formation in the 25 January 2007 CME/Flare Limb Event: Microwave Observations with the RATAN-600 Radio Telescope
Abramov-Maximov, V. E.; Grigoryeva, I. Y.; Borovik, V. N. +4 more
A CME/flare event occurred at the eastern limb on 25 January, 2007. Seven successive multi-wavelength scans in the range 1.8 cm - 5.0 cm were obtained with the RATAN-600 radio telescope starting just at the beginning of the post-eruptive arcade formation (30 min after a C6.3 flare peak) and lasting for 3.5 hours. The conditions were favorable to s…
The He II Lines in the Lyman Series Profiles of Solar Prominences
Vial, J. -C.; Ajabshirizadeh, A.; Ebadi, H.
The hydrogen and helium lines are the most prominent lines in the solar prominences spectra. Observations with the SUMER spectrometer onboard SOHO showed that there are weak lines in the blue wings of the Lyman series which affect their profiles. They were all identified as He II lines in the Lyman series wings, except for the Lα line whose profil…