Tomographic Imaging of the Velocity and Magnetic Fields in the Sun's Atmosphere

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The proposal is to develop an instrument that can simultaneously measure the sound speed and magnetic fields at three heights in the solar atmosphere. The instrument will use magneto-optical filters tuned to the solar absorption lines at 422 nm (Ca I), 589 nm (Na D2), and 770 nm (K) to make measurements of Doppler velocities and longitudinal magnetic field. These lines form in the mid- and low-chromosphere and photosphere, respectively. In addition, the instrument will also use a Fabry-Perot etalon as a narrowband filter to measure the intensity variations of the 1083 nm (He I) line that is formed high in the chromosphere and which shows the location of the "foot points" of coronal holes. Together, the four lines will allow studying wave motions throughout the solar atmosphere. The instrument will record images of the Sun every 10 seconds with a spatial resolution of 1 arc-second. Thus, the project will be fostering the development of existing magneto-optical filter technology to a new level. Upon construction, the telescope will be tested at South Pole for a long period of uninterrupted observations. Both the local and global helioseismic analysis procedures will be utilized to identify and to characterize different types of waves present in the solar atmosphere. These observations will allow determining the structure and dynamics of the Sun's atmosphere through seismic measurements and, thus, improve the atmosphere models, assess the role of waves in heating the chromosphere/corona and driving the solar wind, and better understand how the Sun's atmosphere couples to the interior. The broader impact of the proposed project is two fold. First, there is a potential benefit to the science and to the society because it is believed that the solar atmosphere is a "home" to many phenomena that can have a direct effect on the solar activity, including flares, coronal mass ejections, and the solar wind. Understanding the structure and dynamics of the solar atmosphere will therefore lead to a better understanding of the Sun-Earth connection. The collected data will be made available to other researchers at DVDs. The broader audience of general public will be reached through presentations at high schools, libraries, and community events, and news articles in the general press. Most of the research materials will also be placed in the Web.