I am a PhD student in the Astronomy & Astrophysics group of the Department of Physics and Astronomy at Macquarie University. I currently focus mostly on double-degenerate central stars of planetary nebulae, including plasma diagnostics and photoionization modeling. My research aims to determine double-degenerate central stars of planetary nebulae, stellar evolutionary stage and distance in conjunction with Type Ia supernova progenitors.

A planetary nebula is ionized plasma clouds, produced from a hot central star of low to intermediate mass that is towards the end of its evolution. Its origin has been the subject of several investigations in recent years. It is a key point to understand the late evolution of low- and intermediate-mass stars and the physical mechanism of mass loss for stellar evolution. (Iben, 1995) Its properties of low-density dusty plasma may answer the remaining questions about the chemical composition of the interstellar medium and the chemical enrichment of our galaxy. (Parker et al., 2006)

There are two possible mechanisms for the formation of the planetary nebulae: single stars and binary central stars. The first mechanism involves a combination of magnetic fields and stellar rotation, which produces an axisymmetric mass-loss and expends stellar winds. (Blackman, 2004; Matt et al., 2004) However, we observe certain non-spherical shapes arguing for the binary scenario. (De Marco, 2006) Hence, planetary nebulae depict a remarkably diverse range of shapes, ranging from axisymmetric to non-spherical forms.

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Planetary Nebula NGC 2818, © 2009 NASA, ESA, Hubble Heritage Team.

Previous researches:
Prior to taking up my research position at Macquarie University, I was a postgraduate student in the Centre for Plasma Physics of the Department of Physics & Astronomy at the Queen's University of Belfast. My research project focused on the linear and nonlinear studies of acoustic-excitations in the presence of suprathermal electrons background. The propagation of acoustic nonlinear excitations in plasmas is particularly important, which lies at the intersection of plasma physics and nonlinear dynamics. We have observed the formation of solitary waves, which are associated with the mutual compensation between nonlinearity and dispersion. This topic is of particular interest since electron-accoutsic solitary waves often occur in space plasmas e.g. the Earth's bow shock, (Thomsen at al., 1983) the auroral magnetosphere, (Tokar & Gary, 1984) and the Broadband Electrostatic Noise. (Matsumoto at al., 1994) I investigated the existence domains of stationary profile solitary waves and discussed how their characteristics depend on plasma parameters. (Danehkar et al., 2011)

Previously, I have been awarded a Marie-Curie fellowship for studying the BRST (Becchi, Rouet, & Stora, 1974; Tyutin, 1975) couplings between a background field (BF) and dual formulation of linearized gravity at the University of Craiova. The BRST formalism presents the local gauge symmetry as being a replacement for the original gauge symmetry. It provides useful way of studying the consistent interactions in gauge theories in terms of the deformation of the solution to the master equation. (Barnich & Henneaux, 1993) This investigation revealed that, for the first time, the dual formulation of linearized gravity is coupled to another theory, namely the topological BF model in (4 + 1)-dimensional spacetime. (Bizdadea et al., 2009; Bizdadea et al., 2009)

I have also used the (3 + 1)-covariant approach to general relativity. In this approach, we rewrite equations governing relativistic fluid dynamics by using project vector and project symmetric traceless tensors instead of metrics. I investigated the dynamic equations governing the Weyl curvature. The results show that the nonlocal interactions (tidal force and gravitational wave) are inconsistent without the magnetic part of the Weyl curvature. (Danehkar, 2009)