Main Objective: The proposed objective is the estimation of the plasma beta parameter for different magnetic field regimes: (a) for quiet sun and faculae, (b) for coronal holes. Scientific Justification: JUSTIFICATION We would like to ask for support to HINODE for the following GREGOR campaign, already scheduled, and IRIS (program approved). We are also submitting the OBS-IDs to IRIS at the time of this submission. The proposal plan is a summary of the proposal submitted to GREGOR, and awarded with 12 days. The proposed objective is the estimation of the plasma beta parameter for different magnetic field regimes: (a)for Quiet Sun and faculae, (b) for Coronal Holes. The plasma beta parameter is defined as the ratio of the magnetic pressure over the kinetic pressure. The plasma beta is usually estimated with different models of magnetic field, density and temperature. In this proposal we propose to observe different Sun layers where we can retrieve these magnitudes, namely, the magnetic field, density and temperature through the most direct possible methods from the proposed observing campaign. The plasma beta parameter is very important for different physical phenomena in the solar atmosphere, such as solar wind and how it is accelerated. In the most dense layers, such as the photosphere, it is also relevant, because small magnetic changes in this layer or local heating can affect the magnetic loops showing higher values in the beta parameter. The chromosphere, transition region and corona are the least explored layers, and the plasma beta is not so well known for these layers. (a) The structure of the solar atmosphere is complex, due to the interchanging roles of plasma and magnetic pressure. This behaviour is usually described by the plasma beta. Studies about the plasma beta in different layers of the solar atmosphere and their dependence with height is presented in Rodriguez Gomez (2017, 2018). Recently we have extended this study of the plasma beta evolution in the solar corona for different features as Quiet Sun, faculae and Active Regions (i.e, closed magnetic field regime). (b) Coronal holes are an important quiet solar source for space weather events. They are observed as dark coronal structures compared with their surroundings in far ultraviolet or X-ray filters. Since they are characterised by an imbalance in the magnetic flux, the estimation of the plasma beta is very interesting for different reasons: because of the aforementioned magnetic field; due to the very reduced plasma pressure; and more interestingly, as a test bench for flux transport models. Coronal holes are very common in the decay and minimum of the solar cycle. Since they exhibit a more unipolar magnetic carpet than the regular Quiet Sun (QS), the interest lies on relatively low-medium magnetic field, more unipolar (open), as another magnetic regime to estimate the plasma beta parameter. SCIENTIFIC OBJECTIVES The main objective of this campaign is to have co-spatial and co-temporal observations which can provide constraints to the values on magnetic field, temperature and density to help us to complete a more detailed depiction of the plasma beta with height, which in turn will be useful for solar wind and many other aspects. This description will use the observations as follows. HINODE/SP may provide spectropolarimetric data in the photospheric 6301 and 6302 A lines, for two similar heights in the photosphere. This photospheric magnetic field can be extrapolated to compute the magnetic pressure, or used as input for magnetic model, for different heights. The retrieved magnetic field can be used for further forward modelling of the magnetic field or using photospheric magnetic field and extrapolate with PFSS or NLFFF. Another description of temperature can be obtained through magnetic field extrapolations. HINODE/XRT is the most adequate instrument to probe coronal layers with imaging, and to infer heights in small loops or other structures. XRT differential emission measures curves can be useful for inferring densities. HINODE/EIS can complement the chromospheric information obtained by GREGOR, and IRIS observations. Other coordinated observations, as with IRIS, will help to complete the picture of the plasma beta diagram with height. References: Rodriguez Gomez, J.M , 2017, PhD thesis Rodriguez Gomez. J.M, Vieira ,L., Dal Lago,A., Palacios,J., 2018, Ap.J., 852,137 |
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