Search Publications
Solar total and spectral irradiance reconstruction over the last 9000 years
Solanki, S. K.; Wu, C. -J.; Krivova, N. A. +1 more
Context. Changes in solar irradiance and in its spectral distribution are among the main natural drivers of the climate on Earth. However, irradiance measurements are only available for less than four decades, while assessment of solar influence on Earth requires much longer records.
Aims: The aim of this work is to provide the most up-to-dat…
Shock location and CME 3D reconstruction of a solar type II radio burst with LOFAR
Eislöffel, J.; Mann, G.; Anderson, J. +62 more
Context. Type II radio bursts are evidence of shocks in the solar atmosphere and inner heliosphere that emit radio waves ranging from sub-meter to kilometer lengths. These shocks may be associated with coronal mass ejections (CMEs) and reach speeds higher than the local magnetosonic speed. Radio imaging of decameter wavelengths (20-90 MHz) is now …
Solar cycle 24: An unusual polar field reversal
Janardhan, P.; Fujiki, K.; Ingale, M. +2 more
Context. It is well known that the polarity of the Sun's magnetic field reverses or flips around the maximum of each 11 year solar cycle. This is commonly known as polar field reversal and plays a key role in deciding the polar field strength at the end of a cycle, which is crucial for the prediction of the upcoming cycle.
Aims: We aim to inv…
Revised historical solar irradiance forcing
Egorova, T.; Schmutz, W.; Rozanov, E. +5 more
Context. There is no consensus on the amplitude of historical solar forcing. The estimated magnitude of the total solar irradiance (TSI) difference between the Maunder minimum and the present time ranges from 0.1 to 6 W m-2 making the simulation of the past and future climate uncertain. One reason for this disagreement is the applied ev…
Mapping the solar wind HI outflow velocity in the inner heliosphere by coronagraphic ultraviolet and visible-light observations
Sasso, C.; Romoli, M.; Andretta, V. +18 more
We investigated the capability of mapping the solar wind outflow velocity of neutral hydrogen atoms by using synergistic visible-light and ultraviolet observations. We used polarised brightness images acquired by the LASCO/SOHO and Mk3/MLSO coronagraphs, and synoptic Lyα line observations of the UVCS/SOHO spectrometer to obtain daily maps of solar…
Solar meridional circulation from twenty-one years of SOHO/MDI and SDO/HMI observations. Helioseismic travel times and forward modeling in the ray approximation
Gizon, Laurent; Liang, Zhi-Chao; Birch, Aaron C. +2 more
Context. The solar meridional flow is an essential ingredient in flux-transport dynamo models. However, no consensus on its subsurface structure has been reached.
Aims: We merge the data sets from SOHO/MDI and SDO/HMI with the aim of achieving a greater precision on helioseismic measurements of the subsurface meridional flow.
Methods: Th…
Long-lasting injection of solar energetic electrons into the heliosphere
Temmer, M.; Veronig, A.; Gómez-Herrero, R. +3 more
Context. The main sources of solar energetic particle (SEP) events are solar flares and shocks driven by coronal mass ejections (CMEs). While it is generally accepted that energetic protons can be accelerated by shocks, whether or not these shocks can also efficiently accelerate solar energetic electrons is still debated. In this study we present …
Observing and modeling the poloidal and toroidal fields of the solar dynamo
Schüssler, M.; Schunker, H.; Duvall, T. L. +1 more
Context. The solar dynamo consists of a process that converts poloidal magnetic field to toroidal magnetic field followed by a process that creates new poloidal field from the toroidal field.
Aims: Our aim is to observe the poloidal and toroidal fields relevant to the global solar dynamo and to see if their evolution is captured by a Babcock-…
Jovian electrons in the inner heliosphere. Proposing a new source spectrum based on 30 years of measurements
Potgieter, M. S.; Heber, B.; Vogt, A. +2 more
Context. Since the Pioneer 10 flyby of Jupiter it has become well known that electrons of Jovian origin dominate the lower MeV range of charged energetic particles in the inner heliosphere.
Aims: Because the Jovian source can be treated as point-like in numerical models, many attempts to investigate charged particle transport in the inner hel…
Hot prominence detected in the core of a coronal mass ejection. III. Plasma filling factor from UVCS Lyman-α and Lyman-β observations
Heinzel, P.; Jejčič, S.; Bemporad, A. +1 more
Context. We study an erupting prominence embedded in the core of a coronal mass ejection that occurred on August 2, 2000, and focus on deriving the plasma filling factor of the prominence.
Aims: We explore two methods for measuring this factor along the line of sight. They are based on a combination of visible-light and ultraviolet spectrosco…