Search Publications
A statistical survey of the magnetotail current sheet
Balogh, A.; Zhang, T. L.; Nakamura, R. +8 more
Using Cluster magnetometer data during summer 2001 and 2002, when the spacecraft traversed the magnetotail, we have performed a survey of current sheet and its current. We applied a superposed epoch analysis to simple, monotonous current sheet crossings and obtained a statistical profile of the current sheet. We find that the averaged structure of…
Solar wind responses to the solar activity cycle
Marsch, Eckart
The solar magnetic field and the plasma properties, such as the temperature and density distributions in the solar corona, determine the solar wind stream structure and the extent and dynamics of the entire heliosphere, including its global magnetic field. The variation of the solar wind (coming in the form of steady fast streams, variable slow fl…
Investigation of the cosmic ray ground level enhancements during solar cycle 23
Wang, Jingxiu; Wang, Ruiguang
Major solar energetic particle events associated with large solar flares can give rise to cosmic ray ground level enhancements (GLEs). Up to December 2003 during solar activity cycle 23, 13 GLEs (Number from 55 to 67) have been recorded by the worldwide network of neutron monitors. Nine of the 13 GLEs (69%) originated from the southern hemisphere …
Subsurface characteristics of sunspots
Kosovichev, Alexander G.
Time distance helioseismology provides 3-D subphotospheric maps of sunspots, emerging magnetic structures and associated convective flows. This gives us new insights into the basic physical processes inside the Sun, formation of magnetic structures in the solar plasma and mechanisms of solar activity. Recent results from the MDI instrument on SOHO…
Coronal mass ejections associated with polar crown filaments
Wang, Yuming; Wang, Jingxiu; Zhou, Guiping
In the sample of 301 well identified earth-directed halo coronal mass ejections (CMEs) from March 1997 to December 2003, all 21 CMEs associated with polar crown filament (PCF) eruptions are analyzed. Here, the PCFs are viewed as the filaments that partially or totally lie along the boundaries of polar coronal holes, with average length over 1000″,…
Distributions of suprathermal ions near hot flow anomalies observed by RAPID aboard Cluster
Dandouras, I.; Facskó, G.; Daly, P. +4 more
A series of events having signatures of hot flow anomalies (HFA) observed by the magnetic field, plasma, and energetic particle instruments aboard the Cluster spacecraft upstream of the Earth's bow shock in February-April 2003 are investigated. During this period, the separation of the four satellites (up to about 10,000 km) allowed determining th…
The sun, space weather and GIC effects in Sweden
Lundstedt, H.
The solar activity drives the space weather on short-terms and the space climate on long-terms. Being close to the auroral oval has made Swedish electrical systems particularly vulnerable to space weather. Requirements for long-term planning of energy production has now also created an interest in space climate. A short description of the Swedish …
Helioseismic sensing of the solar cycle
Howe, R.; Komm, R.; Hill, F.
All quantities observed with helioseismic methods, such as frequencies, width, and amplitudes of acoustic waves, vary with the solar cycle. However, they relate to the dynamics and structure in different parts of the solar convection zone. The rotation rate varies with the solar cycle, showing the so-called torsional oscillation pattern, from the …
Multi-point study of the magnetotail current sheet
Nakamura, R.; Baumjohann, W.; Runov, A.
This review summarizes the magnetotail current sheet observations by the Cluster spacecraft during July-October 2001. Due to four-point measurements and the tetrahedron configuration of the spacecraft constellation we are able to separate spatial and temporal variations and to estimate gradients and characteristic scales of structures in the curre…
The application of slim disk models to ULX: The case of M33 X-8
Cappelluti, N.; Grandi, P.; Rodriguez, J. +8 more
A comparative XMM-Newton archival data spectral study of the ultraluminous X-ray source (ULX) M33 X-8 has been performed by using both the standard disk model and the newly developed slim disk models. The results of this analysis tend to confirm the hypothesis that M33 X-8 is an X-ray binary with a stellar-mass black hole accreting at super-Edding…