Transcript Supernova
Supernova Type 1 Supernova Produced in a binary system containing a white dwarf. The mechanism is the same (?) as what produces the nova event. Nova Nova – Rapid increase in luminosity of a white dwarf in a binary system Rotation Accretion disc – material pulled into the Roche lobe of the white dwarf which is eventually deposited on the surface of the white dwarf. Supernova TWO VERY DIFFERENT TYPES OF SUPERNOVAE Supernova Type Type Ia* Type II Maximum Luminosity 3 x 109 Suns 3 x 108 Suns Spectrum No hydrogen lines Lines of many heavy elements Hydrogen lines Continuum Where found Among old star systems (galactic bulge, elliptical galaxies) Among young star systems (star-forming regions in disk galaxies) Parent Star White dwarf in binary system Massive star (usually a red supergiant) Trigger mechanism Mass transfer from companion Collapse of iron core Explosion mechanism Thermonuclear explosion of carbon/oxygen core --> iron Rebound shock from neutron star surface: neutrino pressure Left behind Nothing Neutron star Debris Mostly iron All kinds of elements *Types Ib and Ic supernovae are unusual supernovae that have most of the properties of type II supernovae, except that their spectra show no hydrogen lines. Supernova Type 1 Supernova Occurs when the mass of the white dwarf reaches 1.4 M Recall – the white dwarf is supported by electron degeneracy pressure. If the accreted mass goes above this value, electron degeneracy pressure cannot support the inward gravitational pull. The core will contract and heat up until carbon will fuse rapidly and explosively. Chandrasekhar Mass – The mass required to drive carbon fusion (equal to 1.4 M) Supernova Type 1 Supernova Carbon-Detonation Supernova – Supernova produced by the rapid fusion of carbon in a white dwarf. In looking at the spectra of the supernova remnants, very little hydrogen spectra is observed. This might or might not make sense, because the white dwarf has little hydrogen to begin with, but the companion star has hydrogen. Supernova Type 1 Supernova Type 1 Supernova – the violent explosion of energy triggered by carbon/oxygen fusion in the core of a white dwarf in a binary system. It is generated by the accretion of hydrogen from the companion star. The Type 1 Supernova event is not completely understood Current thinking A – Type 1 Supernova occur only if all of the hydrogen in the outer shells of the companion is transferred to the surface of the dwarf. Helium will then begin to accrete on the surface of the dwarf. Helium requires much higher temperature to fuse, and this higher temperature explosive fusion might be enough to drive the core to rapid carbon/oxygen fusion. When the surface layer explodes, the explosion can be violent enough to raise the core temperature above the 7 x 108 K required for the fusion of the carbon/oxygen core of the white dwarf. The carbon/oxygen fuse explosively, blowing the entire system into space and leaving nothing behind. Supernova Type 1 Supernova Type 1 Supernova – the violent explosion of energy triggered by carbon/oxygen fusion in the core of a white dwarf in a binary system. It is generated by the accretion of hydrogen from the companion star. The Type 1 Supernova event is not completely understood Current thinking B – Once the Chandrasekhar limit is reached, electron degeneracy pressure can no longer support the strong gravitational pull, the temperature will rise, and carbon will fuse explosively in the dwarf. The carbon/oxygen fuse explosively, blowing the entire system into space and leaving nothing behind. Supernova Type 1 Supernova Type 1 Supernova – the violent explosion of energy triggered by carbon/oxygen fusion in the core of a white dwarf in a binary system. It is generated by the accretion of hydrogen from the companion star. The Type 1 Supernova event is not completely understood Current thinking C – The lack of hydrogen in the spectrum of the remnants suggests that the Type 1 event happens after the companion has been reduced to a white dwarf. The two might collide and form one star, which will collapse due to its mass and cause the carbon-detonation supernova. The carbon/oxygen fuse explosively, blowing the entire system into space and leaving nothing behind.