Gravastar Star With no Horizon with ultracompact and very density possible? Is that possible with some strange Quantum Effect could give rise to a completely new kind of a star? Gravastar(Gravitational Vacuum Star) an object hypothesized in astrophysics as an alternative to the black hole theory.The notion of gravastars builds on Einstein's theory of general relativity and imposes a universal "smallest size" that is known to exist according to well-accepted quantum theory. This size is known as the Planck length and is derived using the speed of light, Planck's constant and the gravitational constant. Quantum theory says that any scale smaller than the Planck length is unobservable and meaningless to physics and physicists. This limit can be imposed on the wavelength of a beam of light so as to obtain a limit of blue shift that the light can undergo. However, in the presence of an event horizon, the blue shift diverges.

In the original formulation by Mazur and Mottola, gravastars contain a central region featuring a p=-ρ false vacuum or "dark energy", a thin shell of p=ρ perfect fluid, and a true vacuum p=ρ=0 exterior. The dark energy like the behavior of the inner region prevents collapse to a singularity and the presence of the thin shell prevents the formation of an event horizon, avoiding the infinite blue shift. The inner region has thermodynamically no entropy and may be thought of as a gravitational Bose-Einstein condensate. Severe red-shifting of photons as they climb out of the gravity well would make the fluid shell also seem very cold, almost absolute zero.
Of course unknown "strange Quantum Effects" could do anything, but this letter reports calculations which suggest that at least one of the LIGO gravitational wave events is consistent with black holes but not with gravastars. That doesn't rule out the possibility of gravastars and black holes existing, but it speaks quite strongly against the idea that all the phenomena attributed to black holes are actually due to gravastars.