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Exploring Supernovae and Gamma-Ray Bursts in Post-Main Sequence Stars Evolution

Dive into the fascinating evolution of stars after their main sequence as fusion progresses, leading to the formation of heavier elements and iron cores. Explore the detailed stages of supernova fusion and learn about the rapid processes involved. Discover the life clock of massive stars, from main sequence to red giant expansion, culminating in the final fusion stages. Uncover the intriguing characteristics of Type I and Type II supernovae, including the famous SN 1987A event in the Large Magellanic Cloud.

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Exploring Supernovae and Gamma-Ray Bursts in Post-Main Sequence Stars Evolution

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  1. 0 Supernovae and Gamma-Ray Bursts

  2. 0 Summary of Post-Main-Sequence Evolution of Stars Supernova Fusion proceeds; formation of Fe core. Subsequent ignition of nuclear reactions involving heavier elements M > 8 Msun Fusion stops at formation of C,O core. M < 4 Msun

  3. 0 Fusion of Heavier Elements 126C + 42He → 168O + g 168O + 42He → 2010Ne + g 168O + 168O → 2814Si + 42He Onset of Si burning at T ~ 3x109 K → formation of S, Ar, …; → formation of 5426Fe and 5626Fe → iron core Final stages of fusion happen extremely rapidly: Si burning lasts only for ~ 2 days.

  4. 0 The Life “Clock” of a Massive Star (> 8 Msun) Let’s compress a massive star’s life into one day… 12 H → He 11 1 Life on the Main Sequence + Expansion to Red Giant:22 h, 24 min. H burning 2 10 9 3 4 8 7 5 6 H → He He → C, O 12 11 1 2 10 He burning: (Horizontal Branch)1 h, 35 min, 53 s 9 3 4 8 7 5 6

  5. He → C, O H → He 0 12 11 1 C → Ne, Na, Mg, O 2 10 3 9 4 C burning: 6.99 s 8 7 5 6 C → Ne, Na, Mg, O H → He Ne → O, Mg He → C, O Ne burning: 6 ms 23:59:59.996

  6. 0 C → Ne, Na, Mg, O H → He Ne → O, Mg He → C, O O → Si, S, P O burning: 3.97 ms 23:59:59.99997 C → Ne, Na, Mg, O H → He Ne → O, Mg He → C, O O → Si, S, P Si → Fe, Co, Ni The final 0.03 msec!! Si burning: 0.03 ms

  7. 0 Observations of Supernovae Total energy output: DEne ~ 3x1053 erg (~ 100 L0 tlife,0) DEkin ~ 1051 erg DEph ~ 1049 erg Lpk ~ 1043 erg/s ~ 109 L0 ~ Lgalaxy! Supernovae can easily be seen in distant galaxies.

  8. 0 SN 2006X in M 100 Observed with the MDM 1.3 m telescope

  9. 0 Type I and II Supernovae Core collapse of a massive star: Type II Supernova Light curve shapes dominated by delayed energy input due to radioactive decay of 5628Ni Type II P Collapse of an accreting White Dwarf exceeding the Chandrasekhar mass limit → Type Ia Supernova. Type II L Type I: No hydrogen lines in the spectrum Type II: Hydrogen lines in the spectrum Type Ib: He-rich Type Ic: He-poor

  10. 0 The Famous Supernova of 1987:SN 1987A Unusual type II Supernova in the Large Magellanic Cloud in Feb. 1987 Before At maximum Progenitor: Blue supergiant (denser than normal SN II progenitor) 20 M0; lost ~ 1.4 – 1.6 M0 prior to SN Evolved from red to blue ~ 40,000 yr prior to SN

  11. 0 The Remnant of SN 1987A Ring due to SN ejecta catching up with pre-SN stellar wind; also observable in X-rays. vej ~ 0.1 c Neutrinos from SN1987 have been observed by Kamiokande (Japan) Escape before shock becomes opaque to neutrinos → before peak of light curve provided firm upper limit on ne mass: mne < 16 eV

  12. 0 Remnant of SN1978A in X-rays Color contours: Chandra X-ray image White contours: HST optical image

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