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IBIS 2.0 will help to answer several open questions on plasma and magnetic field at different heights in the solar atmosphere, e.g.:
Are there chromospheric counterparts of umbral dots?
Are umbral dots heated due to oscillatory magnetoconvection, penetration of hot plasma between thin flux tubes or electric currents?
Are moving magnetic features extensions of penumbral filaments?
Which is the source of plasma jets in sunspot light bridges?
Is the overlying magnetic canopy responsible for both the penumbra formation and decay processes?
IBIS 2.0 is expected to perfom highly stable imaging spectropolarimetry, which will allow:
to monitor the quiet Sun at the solar disc center, also useful for solar irradiance estimates;
to probe MHD waves phenomena as a function of spatial position, time and atmospheric height in and around the main features of the solar atmosphere;
to describe the spectropolarimetric signatures in the Stokes profiles during magnetic flux cancellation in the low solar atmosphere;
to derive signatures of the rising plasma in emerging flux regions, e.g., time delays and vertical velocities at different atmospheric heights.
IBIS 2.0 will allow to study the chromospheric dynamics. In particular, observations at the CaII 854.2 nm spectral line will allow to study chromospheric phenomena, such as magnetic reconnection, plasma acceleration, flare secondary effects, etc, and answer the following questions:
Which is the response of the solar chromosphere to the energy release due to the interaction between pre-existing and emerging magnetic flux?
Can the height of the magnetic reconnection during a flare influence the amount of emission at photospheric and chromospheric level?
What are the polarimetric properties of flare ribbons?
IBIS 2.0 will be employed in coordinated observing campaign with other ground-based and space telescopes in order to exploit the complementary characteristics of this instrument with other present and incoming instruments dedicated to the study of the Sun:
observing in other energy bands (NIR and NUV),
covering other time windows,
using other measurement methods (spectrographs),
exploiting different polarimetric sensitivity.
A minimum FOV of around 60” x 60”, with a spatial resolution of about 0”.16 will allow investigating all the above-mentioned physical processes. The main technical constraint that is able to satisfy the scientific requirements is its wide flexibility in the spectral sampling, i.e., using a different number of points along each line and different steps. Two main observation modes are required for each wavelength scan: a scan of the spectral lines taking 1 image for each spectral point sequentially or taking several images at the same spectral points for each step. Moreover, it is also necessary to guarantee the possibility to sample more than one spectral line during an observing run, both sequentially and repeating the scan of each line several times before to scan a subsequent one.
Figure 1. (Adapted from Murabito et al. 2016). Maps of intensity, magnetic field strength, and inclination angle (first, second, and third column) on 2012 May 28 at 14:00 UT (top, before penumbra formation) and on 2012 May 29 at 14:31 UT (bottom, after penumbra formation), obtained from the SIR inversion of the Stokes profiles of the Fe I 630.25 nm line acquired by IBIS. The red or black contours indicate the edge of the pore and of the umbra as seen in the continuum intensity image. In the top panel of the second column, the contours indicate the edge of the pore as seen in the continuum intensity image (red contour) and the annular zone as seen in the magnetic field image (yellow contour), respectively. LOS velocity maps (fourth column) are deduced from the Doppler shift of the centroid of the Fe I 630.25 nm line profile. Downflow and upflow correspond to positive and negative velocities, respectively. The red or black square encloses a region where the transition from inverse to classical Evershed flow during penumbra formation is clearly visible.
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