Compact stars in $$f(R,\mathcal {T})$$ f ( R , T ) gravity

Abstract

In the present paper we generate a set of solutions describing the interior of a compact star under f (R, T ) theory of gravity which admits conformal motion. An extension of general relativity, the f (R, T ) gravity is associated to Ricci scalar R and the trace of the energy-momentum tensor T . To handle the Einstein field equations in the form of differential equations of second order, first of all we adopt the Lie algebra with conformal Killing vectors (CKV) which enable one to get a solvable form of such equations and second we consider the equation of state (EOS) p = ωρ with 0 < ω < 1 for the fluid distribution consisting of normal matter, ω being the EOS parameter. We therefore analytically explore several physical aspects of the model to represent behavior of the compact stars such as-energy conditions, TOV equation, stability of the system, Buchdahl condition, compactness and redshift. It is checked that the physical validity and the acceptability of the present model within the specified observational constraint in connection to a dozen of the compact star candidates are quite satisfactory.

Gravastars in f(R,T) gravity

“…In the present project our motivation is to study the gravastar under one of the alternative gravity theories, namely f (R, T ) gravity [27] and to observe different physical features of the object -their nontriviality as well as triviality. Actually our previously performed successful works on the initial phases of compact stars under alternative gravity [28,29] motivate us to exploit the alternative formalism to the case of the gravastar, a viable alternative to the ultimate stellar phase of a black hole.…”

Tuning the Biradicaloid Nature of Polycyclic Aromatic Hydrocarbons: The Effect of Graphitic Nitrogen Doping in Zethrenes

“…Scheme 1a shows for HZ three aromatic sextets in the open-shell biradical form whereas in the closed-shell quinoid Kekulé form only two sextets are present. Thus, HZ is expected to exhibit significant biradicaloid character as has been shown explicitly by means of density functional theory (DFT) [11,13] and multireference averaged quadratic coupled cluster (MR-AQCC) theory [16] calculations. As example for this open-shell character, Scheme 1b shows the density of unpaired electrons computed by the latter method indicating the positions of strongest radicaloid character.…”

“…[8,9] Zethrenes and their derivatives represent attractive examples of such unconventional electronic materials. [10][11][12][13][14][15][16][17] The name of this class of PAHs comes from the zshaped molecular skeleton formed by head-to-head annelation of two phenalenyl rings with or without intermediate benzene ring spacers. In heptazethrene (HZ, Scheme 1a), one benzene ring is inserted between the two phenalenyl rings.…”

Compact stars with specific mass function

“…So, there is only the need to consider the generalized Tolman-OppenheimerVolkov (TOV) equation for anisotropic fluid distribution, given by [30,31] …”