### Speaker

Dr
Hossein Ghaffarnejad
(Semnan University of IRAN)

### Description

Combinations of Lovelock polynomials $R^2,R_{\mu\nu}R^{\mu\nu}$ and
$R_{\mu\nu\eta\delta}R^{\mu\nu\eta\delta}$ is added with
Einstein-Hilbert action to obtain interior metric of an anisotropic
spherically symmetric collapsing (ASSC) stellar cloud. We assume
that time dependent interior metric of the ASSC cloud is flat
Minkowski at beginning of the collapse. We solved linearized metric
equation and obtained convergent series solutions for the interior
metric components, mass density, radial, transverse and isotropic
pressures, time dependent barotropic index and dimensionless
anisotropic parameter. Ricci and Kretschmann scalars for our
solutions are not singular at the beginning and duration of the
collapse. Mathematical calculations predict that the collapsing
cloud reach to its final state (compact object) and the collapse
will be stopped at a finite time $t_C$. Also we obtain particular
times $t_E$ and $t_A$ where the singularity and apparent horizon are
formed. Singularity can not be observed by an external observer
because of $t_E>t_A>t_C$.

### Primary author

Dr
Hossein Ghaffarnejad
(Semnan University of IRAN)