Research Projects

Solar eruptive phenomena, viz. solar flares and coronal mass ejections (CMEs), are one of the main drivers of space weather. The coronal magnetic field (B) plays an essential role in the formation, evolution, and dynamics of small and large-scale structures in the solar corona. One of the biggest challenges in solar physics is to measure B fields directly from observations, especially in the chromosphere and corona. Several methods exist to infer the B fields in the solar atmosphere. However, they are restricted to either the lower chromosphere or upper corona. These solar eruptions often accelerate energetic electrons, which produce radio emissions detectable in the GHz, microwave, metric, and deca-hectometer (DH) frequency ranges, which can be used for studying the near-Sun early evolution, kinematics, and dynamics of CMEs. The estimated magnetic fields for the CMEs from these radio emissions can be used to determine the geo-effectiveness of the CME. Since radio techniques provide access to observations of solar, heliospheric, and ionospheric space weather phenomena, they are considered one of the most practical approaches to probing the magnetic field in the solar atmosphere. This proposal aims to develop a solar radio heliograph that operates from 1-18 GHz, covering both the upper chromosphere and the inner corona. It will enable us to study regions of the Sun that are currently inaccessible by other means. The radio emissions from the corona and chromosphere, including the Sun's limb and disc, can be observed simultaneously without relying on artificial occultation methods (such as coronagraphs). At present, no such instrument is currently operational in the Asian time zone (2-8 UT), making this project a valuable complement to India's maiden space-based solar mission, Aditya-L1, which has no radio instruments. Since the ionospheric cut-off (~ 15 MHz) provides an EM wave window in radio frequencies, it makes it possible to do radio observations of astronomical sources from the Earth. This radio telescope will significantly enhance the understanding of solar dynamics and provide a unique tool for space weather research, particularly when Aditya-L1 data can be combined with ground-based radio observations. The research plan is structured into three work packages: 1. Design, develop and characterize an antenna feed that works in the 1-18 GHz range to be used as a primary receiving element. 2. Development of an all-Stokes correlator on a high-speed FPGA at high temporal resolution and at spot frequencies to record small-scale variation and ~60 dB dynamic range to record faint emission. 3. Trial observations with the solar radio heliograph of the solar corona and chromosphere radio frequencies. This will complement the existing Multi-Application Solar Telescope (MAST) operated by the Udaipur Solar Observatory (USO), Physical Research Laboratory, Dept. of Space, Govt. of India., which observes the lower and middle chromosphere.