The DynaMICCS perspective

Abstract

The DynaMICCS mission is designed to probe and understand the dynamics of crucial regions of the Sun that determine solar variability, including the previously unexplored inner core, the radiative/convective zone interface layers, the photosphere/chromosphere layers and the low corona. The mission delivers data and knowledge that no other known mission provides Acronym: dynamics and magnetism from the inner core to the corona of the Sun. for understanding space weather and space climate and for advancing stellar physics (internal dynamics) and fundamental physics (neutrino properties, atomic physics, gravitational moments...). The science objectives are achieved using Doppler and magnetic measurements of the solar surface, helioseismic and coronographic measurements, solar irradiance at different wavelengths and in-situ measurements of plasma/energetic particles/magnetic fields. The DynaMICCS payload uses an original concept studied by Thalès Alenia Space in the framework of the CNES call for formation flying missions: an external occultation of the solar light is obtained by putting an occulter spacecraft 150 m (or more) in front of a second spacecraft. The occulter spacecraft, a LEO platform of the mini sat class, e.g. PROTEUS, type carries the helioseismic and irradiance instruments and the formation flying technologies. The latter spacecraft of the same type carries a visible and infrared coronagraph for a unique observation of the solar corona and instrumentation for the study of the solar wind and imagers. This mission must guarantee long (one 11-year solar cycle) and continuous observations (duty cycle > 94%) of signals that can be very weak (the gravity mode detection supposes the measurement of velocity smaller than 1 mm/s). This assumes no interruption in observation and very stable thermal conditions. The preferred orbit therefore is the L1 orbit, which fits these requirements very well and is also an attractive environment for the spacecraft due to its low radiation and low perturbation (solar pressure) environment. This mission is secured by instrumental R and D activities during the present and coming years. Some prototypes of different instruments are already built (GOLFNG, SDM) and the performances will be checked before launch on the ground or in space through planned missions of CNES and PROBA ESA missions (PICARD, LYRA, maybe ASPIICS).

Probing the Solar Surface: The Oblateness and Astrophysical Consequences

“…These mechanisms are analyzed in Lefebvre et al (2009). Right: the asphericity coefficient (c n ), here of order n = 4, clearly indicates the signatures of the tachocline and the leptocline (see Bedding et al 2007;Turck-Chièze et al 2009). …”

“…Precise estimates are more complex due to the differential rotation of layers, as well as the yet unknown rotation of the core, especially if this core is rotating at a speed higher than that of the surface (it is expected that the core must rotate at a speed about twice that of the surface; Turck-Chièze et al 2009). A higher value is thus expected for the oblateness than the value given by Equation (1).…”

Solar magnetism eXplorer (SolmeX)

“…A similar profile is currently under investigation for the Proba-3 technology mission with its coronagraph ASPIICS [e.g. 30; 31] and was employed for the proposal to the previous ESA M-class call DynaMICCS [32]. However, the major science objectives of these missions are quite different.…”

“…While the basic idea for the formation flight is similar to previously proposed missions such as DynaMICCS [32] and especially COMPASS [1], the spacecraft concept and related issues such as telemetry or the formation flight concept have been newly developed from scratch during the CE study. A short summary of the study report's results are provided in the following.…”

Concluding remarks on solar and stellar activities and related planets

“…This recent result confirms the inability of the standard model to predict properly the observed sound speed (see Figure 2). One now needs to look for the processes which justify this disagreement: microscopic diffusion, opacities, dynamical proocesses (Turck-Chièze et al, 2004a;Turck-Chièze et al, 2009a).…”