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SN1987A in LMC

SUPERNOVAE. J. Isern Institut de Ciències de l’Espai IEEC - CSIC. SN1987A in LMC. Contents. Exploding stars Observational Background Thermonuclear supernovae Core collapse supernovae Fireworks Associated nucleosynthesis The afetrmatch. És el cel inmutable?. Saturn. Venus. Jupiter.

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SN1987A in LMC

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  1. SUPERNOVAE J. Isern Institut de Ciències de l’Espai IEEC - CSIC SN1987A in LMC

  2. Contents • Exploding stars • Observational Background • Thermonuclear supernovae • Core collapse supernovae • Fireworks • Associated nucleosynthesis • The afetrmatch

  3. És el cel inmutable? Saturn Venus Jupiter El cel a la matinada

  4. El firmament medieval Ptolomeu Aristòtil

  5. Historical supernovae • 185 Cen mag = -2 • 1006 (Apr 30th) Lup mag = -9 • 1054 (Jul 4th) Tau mag = -6 (Crab) • 1181 (Aug 6th) Cas mag = -1 • 1572 (Nov 6th) Cas mag = -4 (Tycho) • 1604 (Oct 9th) Oph mag = -3 (Kepler) • 1680? 1667? Cas mag = 6 ? (Cas A)

  6. SN1572 Cassiopeia Tycho Brahe Nova Stella Uraniborg

  7. S Andromeda: August 31st 1885, visible 18 months: Hartwig Lundmark (1920) estimated a distance of 7 x 105 lyr  1000 times brighter than ordinary novae Z Cen (1895 in NGC5353) 5 times brighter New class of novae: “super-novae” or “extragalactic novae” Andromeda galaxy - HST

  8. Crab Nebula - SN1054 - Crab pulsar Lundmark (1921) suggested for the first time a connection between the Crab nebula and SN1054 Zwicky & Baade (1934) proposed to distinguish among classical novae And “supernovae”

  9. Energetics # The kinetic energy can be obtained from the expansion velocity (vexp ~ 5000 – 10000 km/s) if the time elapsed from the moment of the explosion to the beginning of the nebular phase is known (assuming the Thomson opacity or instance: 0.2 cm2/g)

  10. Energetics # The energy released in photons can be obtained just integrating the light curve: Eph~ 1049 erg (Lmax ~ 10 43 erg/s ) # At maximum light SN are as bright as galaxies. LSN  1010 L # The effective temperature is  2 T #  RSN  2x1015 cm SN are balls of light!

  11. Before 1937 few quality spectra were available • SN1937c in IC 4182, mV ~ 8.4 displayed a completely unusual spectrum (Popper 1937) • Next SN observations showed that all SN were very similar at maximum in brightness and spectral characteristics • Zwicky (1938) and Wilson (1939) proposed the use of SN as distance indicators Popper (1937) but

  12. SN1940c

  13. SNI or SN1937c like H lines are absent SNII or SN1940c like H lines are present

  14. Explosive sources of energy Gravitational collapse Thermonuclear explosion Neutron star Electron degenerate core {12C,16O}{56Ni} q ~ 7x1017 erg/g 1 Mo x q ~ 1051 erg K ~ 1051 erg Eem ~ 1049 erg Lmax ~ 1043 erg/s M ~ 1.4 Mo R ~ 106 cm M ~ 1.4 Mo R ~ 108-109 cm EG ~ 1053 erg K ~ 1051 erg Eem ~ 1049 erg Hoyle & Fowler (1960) Zwicky (1938)

  15. SN1987A neutrinos

  16. Exploding stars • They play a fundamental role in shaping the galaxy • They inject 1051 ergs/explosion in the form of kinetic energy per event • They trigger the formation of new stars • They accelerate cosmic rays • They power intense galactic winds that can even remove the galactic gas and kill the process of star formation • They inject several Mo of freshly synthesized chemical elements, both stable and radioactive. • They play a key role on the origin and evolution of life • They synthesize the elements necessary to build rocky planets • They synthesize the biogenic elements • They can sterilize large regions of the Galaxy

  17. Hipòtesis bàsiques • La rotació és negligible • Els camps magnètics són negligibles L Les estrelles són esfèriques Conservació de la massa

  18. Pressió: ions, electrons i fotons Equilibri hidrostàtic . I: Fs Suposem un canvi de radi en un temps característic  P+dP dA dm dr El temps de resposta gravitatori serà: P Mr Tindrem equilibri sempre que: Fi Fg El terme de pressió serà: Si hi ha equilibri:

  19. Hydrostatic Equilibrium Characteristic times Hydrodynamic time: HD 440 -1/2 Thermal time: 107 yr Nuclear time: 109 yr

  20. Electron degeneracy At high densities e- are dominant If Even at T=0 electrons (and other fermions) are able to exert pressure! Zero temperature structures can exist

  21. The virial theorem P=2/3 e P=1/3 e Non Relativistic Particles Extremely Relativistic Particles Ei = -EG Ei = -1/2 EG During a gravitational transition from an equilibrium configuration to another one, half of the energy is radiated away and half is invested in internal energy. Relativistic stars are not bounded MCh=1.44 <2Ye>2 Mo

  22. 1H,4He Fases de la combustió nuclear Combustió H 4He Combustió He 12C,16O 16O,20Ne,24Mg Combustió Ne Combustió C 16O,24Mg,28Si 28Si,32S... 56Fe Combustió O Combustió Si

  23. Massive stars build an onion like structure through a series of contractions followed by ignitions with iron in the center.

  24. Non relativistic electrons If electrons are non relativistic Hydrostatic equilibrium: It is always possible to find an equilibrium structure The star only needs to contract R decreases when M increases

  25. Nuclear reactions Virial theorem  Ei  E E i ~ MT E G ~ M2 R-1 T ~ M/R  ~ M R-3 Each burning phase occurs at a fixed temperature ~M-2 Light stars ignite nuclear reactions at high densities Electron degeneracy can stop the nuclear burning process  ~ T3 M-2 M<0.08 Mo, H is never ignited M<0.5 Mo, He is never ignited M<8-9 Mo, C is never ignited M<10-12 Mo, Ne is never ignited M>10-12 Mo, Fe cores are formed

  26. Nebuloses planetàries

  27. M<0.5 Mo, form He cores M<8-9 Mo, form C/O cores M<10-12 Mo, form O/Ne During the AGB phase they expel the outer layers and become white dwarfs These limits change in binary systems. If close enough, stars with 2.5 Mo can give He wd of ~ 0.4 Mo Massive white dwarfs form an Fe core that gradually grows with time NGC 6751 If M R  EF When EF >> mec2 electrons become relativistic

  28. Relativistic electrons If electrons are relativistic Hydrostatic equilibrium: It is not possible to find an equilibrium structure There is not a length scale If E < 0 R < 0 The star contracts If E > 0 R > 0 The star contracts The ideal scenario for catastrophic events !

  29. # The energy losses by electron captures depend on the ignition density # The injected energy depends on the velocity of the burning front Nuclear energy release Electron captures He cores always explode CO cores can explode or collapse ONe cores always collapse Fe cores always collapse

  30. M<0.8 M¤ 0.8<M/M¤<8 8<M/M¤<11 11<M/M¤<100 M>100 M¤ t>1/HO 30 Myr<t< 15 Gyr 0.5<Mf /M¤<1.1 CO WD t~10-30 Myr Mf =1.2-1.3 M¤ONe WD • ~1-10 Myr Mf =1.2-2.5 M¤ Fe collapse NS/BH • ~1Myr may or may not explode

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