Electric charge estimation of a new-born black hole
  Though a black hole can theoretically possess a very big charge ($Q/(\sqrt{G}
M) \simeq 1$), the charge of the real astrophysical black holes is usually
considered to be negligible. This supposition is based on the fact that an
astrophysical black hole is always surrounded by some plasma, which is a very
good conductor. However, it disregards that the black holes have usually some
angular momentum, which can be interpreted as its rotation of a sort. If in the
plasma surrounding the hole there is some magnetic field, it leads to the
electric field creation and, consequently, to the charge separation.
  In this article we estimate the upper limit of the electric charge of stellar
mass astrophysical black holes. We have considered a new black hole formation
process and shown that the charge of a new-born black hole can be significant
($\sim 10^{13}$ {Coulombs}). Though the obtained charge of an astrophysical
black hole is big, the charge to mass ratio is small $Q/(\sqrt{G} M) \sim
10^{-7}$, and it is not enough to affect significantly either the gravitational
field of the star or the dynamics of its collapse.
