Questions In Solar Physics Research Articles

Role of magnetic carpet in coronal heating

One of the fundamental questions in solar physics is how the solar corona maintains its high temperature of several million Kelvin above photosphere with a temperature of 6000 K.

International Conference on Challenges for Solar Cycle 24

What will be the nature of magnetic fields at various spatial and temporal scales on the Sun during the next activity cycle? This and other outstanding questions of solar physics were the focus of discussion at the International Conference on Challenges for Solar Cycle 24. Observational solar research is equipped with ever advanced instrumentation during each solar cycle. The use of modern instrumentation for solar observations will yield better results when planned with prior knowledge gained during previous activity cycles. With this motivation, the goal of the conference was to consider the most effective strategies for studying and understanding the solar energetic events of cycle 24.

High-frequency acoustic waves are not sufficient to heat the solar chromosphere

One of the main unanswered questions in solar physics is why the Sun's outer atmosphere is hotter than its surface. Theory predicts abundant production of high-frequency (10-50 mHz) acoustic waves in subsurface layers of the Sun, and such waves are believed by many to constitute the dominant heating mechanism of the chromosphere (the lower part of the outer solar atmosphere) in non-magnetic regions. Such high-frequency waves are difficult to detect because of high-frequency disturbances in Earth's atmosphere (seeing) and other factors. Here we report the detection of high-frequency waves, and we use numerical simulations to show that the acoustic energy flux of these waves is too low, by a factor of at least ten, to balance the radiative losses in the solar chromosphere. Acoustic waves therefore cannot constitute the dominant heating mechanism of the solar chromosphere.

Sun earth connection coronal and heliospheric investigation (SECCHI)

The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory ( STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet imager, two white light coronagraphs, and a heliospheric imager. Two spacecraft with identical instrumentation will obtain simultaneous observations from viewpoints of increasing separation in the ecliptic plane. In support of the STEREO mission objectives, SECCHI will observe coronal mass ejections from their birth at the Sun, through the outer corona, to their impact at Earth. The SECCHI program includes a coordinated effort to develope magneto-hydrodynamic models and visualization tools to interpret the images that will be obtained from the two spacecraft viewpoints. The resulting three-dimensional analysis of CMEs will help to resolve some of the fundamental outstanding questions in solar physics.

Energetic particle experiment ERNE

The Energetic and Relativistic Nuclei and Electron (ERNE) experiment will investigate the solar atmosphere and the heliosphere by detecting particles produced in various kinds of energy release processes. ERNE is at the upper end in energy among the SOHO particle instruments. The instrument will measure the energy spectra of elements in the range Z=1−30. The energy coverage varies dependent on the particle species from a few MeV/n up to a few hundred MeV/n and electrons from 2 to 50 MeV. At high energies, ERNE records also the direction of the incident particles for accurate measurements of the pitch angle distribution of the ambient flux within the viewing cone. Especially the isotope identification capability has been one of the instrument design goals, thus providing new data regarding various fundamental questions in solar physics.