Study and design of a soft X-ray imager and spectrometer for observation of non-flaring Sun

Abstract

The outer most layer of the Sun, also called Corona, reaches temperatures as high as a few million Kelvin much hotter than underlying photosphere and chromosphere. This phenomenon is popularly known as coronal heating. Due to such high temperatures, corona is a strong source of Soft X-rays (<10 kev). Therefore, X-ray telescopes can be used for studying corona without needing an occulter. Such telescopes can be used to probe corona, its composition and the physics behind coronal heating and other solar events such as solar flares. An essential tool missing from arsenal of solar astrophysicists is a soft X-ray imaging spectrometer for the non-flaring corona as the main focus of the solar astrophysicists have been study of solar flares not the background X ray emission. An imaging spectrometer can do both imaging and spectroscopy simultaneously. Although XRT on Hinode has very good resolution imaging, it can’t image the non-flaring sun. The X-ray flux of corona varies by a factor of 1000 during 11 year solar cycle which makes it difficult to design a single instrument which can be used to study corona during flaring as well as non-flaring conditions. I have presented science motivation for studying non-flaring sun in soft X rays and present a novel instrument design for the same. I have used Ospex9 suite of SolarSoftWare to fit observed Soft X-ray spectra from several flares to theoretical models. The modelled spectra is then convolved with instrument effective area to get instrument response to these flares which allows us to find how the instrument is going to behave during such events. I have also presented an algorithm to add counts from different non-flaring observations to find non-flaring solar spectra which can then be used to model instrument response to non-flaring corona.