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Other posts and discussion have left at least one thing clear. That is that only Carbon-Oxygen white dwarf stars will become Type Ia supernovae if enough mass is accreted to exceed MChandra, about 1.39 solar masses. Others can use the more common 1.44 Msolar since it isn't important to detail here.Another thread recently. said:Clearly, a white dwarf cannot survive beyond the mass limit, so there must be some kind of explosion. It's hard for me to imagine that a significant fraction of white dwarfs explode without producing an observable amount of light.
But, the composition of any white dwarf will depend on the mass (and some other factors) of the progenitor star. (The bolded highlights in the following were inserted by Labguy to emphasize certain phrases)
http://72.14.207.104/search?q=cache...e+dwarf"&hl=en&gl=us&ct=clnk&cd=49&lr=lang_en
And:http://www.geocities.com/tonylance/dwarf.htmlWhite dwarf: composition depends on mass of progenitor.
helium
carbon
carbon-oxygen
oxygen-neon-magnesium
So, for the many white dwarfs that formed from the far more numerous small stars there must be a large number of He white dwarfs. And the larger stars also do not form not carbon-oxygen rich dwarfs. Therefore:The interior of a typical white dwarf is mostly composed of carbon and oxygen nuclei, though white dwarfs formed by smaller stars may be mostly helium and those formed by bigger stars may be formed of oxygen, neon, and magnesium.
and: http://chandra.harvard.edu/chronicle/0400/sirius.htmlWikipedia said:A typical white dwarf has half the mass of the Sun yet is only slightly bigger than Earth; this makes white dwarfs one of the densest forms of matter (109 kg·m−3), surpassed only by neutron stars and hypothetical quark stars. The higher the mass of the white dwarf, the smaller the size. There is an upper limit to the mass of a white dwarf, the Chandrasekhar limit (about 1.4 times the mass of the Sun). When this limit is exceeded, the pressure exerted by electrons is no longer able to balance the force of gravity, and the star continues to contract, eventually forming a neutron star. A white dwarf which exceeds this limit (known as the Chandrasekhar limit), typically by mass transfer from a companion star, may explode as a Type Ia supernova via a process known as "carbon detonation".
And: http://online.itp.ucsb.edu/online/gravity_c03/lindblom/pdf/Lindblom.pdf:Harvard? said:If the mass of the white dwarf becomes greater than about 1.4 times the mass of the Sun -- called the Chandrasekhar limit -- it will collapse to become a neutron star or black hole, or blow itself apart in a supernova.
Therefore, from the handy links and quotes provided I would conclude that:The Accretion Induced Collapse of a White Dwarf star can lead to the formation of neutron stars with large angular momenta. These rapidly rotating neutron stars may be subject to non-axisymmetric instabilities which could provide an interesting source of gravitational radiation.
(1) Since smaller stars are far more numerous in the universe than large stars, more white dwarf stars are formed with an He composition.
(2) The largest white dwarf progenitors also do not lead to a carbon-oxygen composition.
(3) Regardless of mass accreted, most white dwarfs will not result in a Type Ia supernova even if MChandra is exceeded.
(4) For all white dwarf stars existing, the required C-O composition needed for a Type Ia supernova could be considered "rare" regardless of accreted mass.
I am very interested in this and related stellar evolution subjects, so if any of this seems unclear or invalid please provide me with a link or two for consideration.
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