collapsar

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collapsar

[kə′lap‚sär]
(astronomy)
A black hole that forms during the gravitational collapse of a massive star.
References in periodicals archive ?
Under their model, massive, rapidly spinning collapsars eject heavy elements whose amounts and distribution are "astonishingly similar to what we observe in our solar system," said Siegel.
Ironically, said Siegel, his team began working to understand the physics of that merger before their simulations pointed toward collapsars as a heavy element birth chamber.
Since the event horizon is the characteristic surface of both the gravitational and inflation collapsars, it is simultaneously the surface of both the "white" and "black" holes.
Because the condition [g.sub.00] = 0 is the collapse condition, the surface of the collapsar is the mirror separating the spaces with both positive and negative flow of the observable time.
It is generally thought that luminous GRBs with bulk Lorentz factors of order [[GAMMA].sub.B] ~ 300 must stem from ultra-relativistic collisionless jets produced by millisecond magnetars and/or collapsars. As discussed in Section 3, in order to penetrate the stellar envelope, the active time scale of the jet produce db ythe central engine ([t.sub.engine]) must be longer than the penetrating timescale, where the latter is ~R/[V.sub.jet].
Heger, "Supernovae, jets, and collapsars," Astrophysical Journal, vol.
They derive the conditions for pulsars and neutron stars to become collapsars. Interestingly, the authors apply their model to the Universe and, based on their results, suggest that the Universe can be considered as a sphere of perfect liquid which is in a state of gravitational collapse (the liquid model of the Universe).
Obviously, only an extremely dense cosmic body can completely be located under its gravitational radius, thus consisting a gravitational collapsar (black hole).
This result leads us to suggest that the signal from Sagittarius A* comes partly from the surface of the collapsar itself, and not entirely from the accretion disc, as is assumed in most current analyses.
The point is that OS showed that there is a common system of coordinates applicable to both the exterior and interior of the collapsar. My article [1] demonstrated that the density distribution of the OS "dust cloud" becomes concentrated near the surface as it shrinks to the gravitational radius; no exotic process like the modern black-hole one of "spaghettification" [6] occurs when a notional spaceship crosses the event horizon.
MacFadyen, who helped improve the collapsar model, concedes that the process of jet formation is not yet well understood, though he says it likely involves some combination of rapid rotation and strong magnetic fields.
The collapsar model can fit this requirement; a superdense disk around the spinning black hole might form and re-form irregularly as matter from the explosion falls back inward.