Dear Sir,
Was the star which exploded and became the crab nebula a traveling mas which hit a space rock and caused the star to collasp into a newly formed blackhole?   Second ? is a blackhole and a  collapsing star one in the same in technical sense?
Thank you,


In answer to your first question, there was no collision with a space rock, the star collapsed on its own and became a neutron star - not a black hole. This neutron star (google) is about 20 km (13 miles) in diameter and emits radiation (x-rays, gamma rays, radio waves) which can be detected on Earth in pulses of 30 per second. Hence it's also called a "pulsar".

In answer to your second question, based on the example above, a collapsing star will not invariably be the same as a black hole. If, as the Crab Nebula case shows, the star lacks a large enough initial mass, then it will only collapse to the neutron star stage - and not all the way to a black hole, from which no radiation can escape. (Some physicists believe a black hole can still emit small amounts of radiation, but that's a separate issue)


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Philip Stahl


I have more than forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics pertaining to sunspot morphology and flare geo-effectiveness.


Astronomy: Worked at university observatory in college, doing astrographic measurements. Developed first ever astronomy curriculum for secondary schools in Caribbean. Gave workshops in astrophysics and astronomical measurements at Harry Bayley Observatory, Barbados. M.Phil. degree in Physics/Solar Physics and more than twenty years as researcher with discovery of SID flares. Developed of first ever consistent magnetic arcade model for solar flares incorporating energy dissipation and accumulation. Develop first ever loop solar flare model using double layers and incorporating cavity resonators.

American Astronomical Society (Solar Physics and Dynamical Astronomy divisions), American Mathematical Society, American Geophysical Union.

Solar Physics (journal), The Journal of the Royal Astronomical Society of Canada, The Proceedings of the Meudon Solar Flare Workshop (1986), The Proceedings of the Caribbean Physics Conference (1985). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'. 'Astronomy and Astrophysics: Notes, Problems and Solutions'.

B.A. Astronomy, M. Phil. Physics

Awards and Honors
American Astronomical Society Studentship Award (1984), Barbados Government Award for Solar Research (1980), Barbados Astronomical Society Award for Service as Journal Editor (1977-91)

Past/Present Clients
Caribbean Examinations Council, Barbados Astronomical Society, Trinidad & Tobago Astronomical Society.

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