Indian scientists have developed a new approach to estimate the amount of density inhomogeneity in the solar atmosphere
A new theoretical model that would help quantify the inhomogeneity in density of the solar corona generated by the turbulence in the electrically conducting, magnetized fluid present as plasma in it has been developed by Indian scientists.
Scientists from Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, an autonomous institute under the Department of Science & Technology, have developed a new approach to estimate the amount of density inhomogeneity in the solar atmosphere, which can be quantified by the density filling factor, which is a fraction of the volume occupied by the over-dense regions with respect to the entire volume of the medium. This method involves numerical simulation.
It needs to be noted here that the electrically-conducting, magnetized fluid present as plasma in the solar corona, which is a dynamic medium, is known to develop magneto hydro dynamic (MHD) wave-driven turbulence. And, this acts as an important catalyst in the heating up of the solar corona by millions of degrees.
Study on solar corona heating problem
If one takes into account the magnitude of the heating process, it would come to light that it is a factor of a thousand times higher than the solar surface. The reason behind heating of the solar corona to such a high temperature hasn’t yet been explained with clarity, but it has come to be known as the ‘coronal heating problem’ in the solar physics community.
Turbulent motion in a fluid is characterized by chaotic changes in pressure and flow velocity. But, due to the extremely hot temperature in the solar corona, the material in the solar corona becomes like a soup of charged particles, which is called plasma. Propagation of the MHD waves in a plasma medium can cause turbulence. When the MHD-wave propagates through the medium, it carries energy, and the amount of energy depends on the density inhomogeneity of the medium.
Model by Indian scientists Dr Samrat Sen and Dr Vaibhav Pant
This model, developed by Dr. Samrat Sen, a post-doctoral researcher at KU Leuven, Belgium, and Dr. Vaibhav Pant, has been published in The Astrophysical Journal. It elaborates on two different methods to calculate the density filling factor. One involves calculation of the density filling factor from the area measurement obtained from the simulated data. The second method in the meanwhile, talks of forward modelling, which is explained as the use of specific model to produce an outcome according to the user interests, used for the spectroscopic measurement to estimate the density filling factor.
The researchers have found that the theoretically estimated values are in good agreement with the observed values in the solar corona. According to the study, MHD wave-driven turbulence increases the filling factor of the overdense structures, and the medium becomes more density homogeneous.