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Early History of Supernovae

Early History of Supernovae . S. R. Kulkarni Caltech Optical Observatories. Key Papers. “On Supernovae” Baade & Zwicky (1934a) “Cosmic Rays From Supernovae” Baade & Zwicky (1934b) “On the Search for Supernovae” Zwicky (1938). Baade & Zwicky (1934a). Novae Facts known by 1934.

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Early History of Supernovae

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  1. Early History of Supernovae S. R. Kulkarni Caltech Optical Observatories

  2. Key Papers • “On Supernovae” Baade & Zwicky (1934a) • “Cosmic Rays From Supernovae” Baade & Zwicky (1934b) • “On the Search for Supernovae” Zwicky (1938)

  3. Baade & Zwicky (1934a)

  4. Novae Facts known by 1934 • Novae occur in our Galaxy at the rate of 30 per year • Hubble studying novae in M31 (initially to determine distance to M31) and a similar rate is found • Nova have typical brightness of -6 mag (with a range of 4 mag)

  5. Other Facts known by 1934 • Tycho Nova (AD 1572) was unusually bright • But “pre-cursor” star for Tycho Nova was not bright • S Andromeda (AD 1885) was very bright • Observed V=7.5 mag • Distance to Modulus to M31, DM=22.2 • [Modern Distance Modulus is 24.5] • Peak brightness -14.7 [-17 modern]

  6. Bright Novae (Baade & Zwicky) • Bright novae are seen in distant nebula • Many of them peak with a brightness similar to the “host” galaxy • MV = -15 • Last about a month • Observed Radiated light is 1048 erg • Two estimates for total energy release • The rate is one per several centuries and conservatively one per thousand years (per galaxy)

  7. Energetics: Baade & Zwicky (1934) • Assume black body radiation from explosion to late times. Assume that we see a small fraction of energy in the optical • Two estimates: 1% to 100% of rest mass of the Sun • Compute the black body radius at peak and divide by time to get velocity • Velocity = 60,000 km/s or v/c=0.2 • This v/c corresponds to 5% of proton rest mass

  8. Baade & Zwicky (1934a) • Super-novae thus represent transition of ordinary stars into a body much smaller in mass and are different from novae • Supernovae are catastrophic

  9. The palomar 18-inch begins SN survey

  10. Fritz Zwicky(1889-1974) 50

  11. SN Spectroscopy • Wide features seen in SN (a consequence of high ejection velocities) • Zwicky begins his classification of SN (based on light curves)

  12. P18 P60 P48 200-inch 50

  13. Baade & zwicky (1934b)

  14. Cosmic Rays • 1912: Hess undertakes high latitude balloon flight and establishes that ionization radiation increases with altitude • 1920: Millikan coins the term “Cosmic Rays” and argues for a photonic origin • 1932: Chadwick discovers the neutron • 1936: Hess wins Nobel Prize. Cosmic rays are now thought to be energetic charged particles (both positive and negative) • AND OF UNKNOWN ORIGIN

  15. Prior to Baade & Zwicky (1934) • It was popular to speculate that cosmic rays came from intergalactic space • B&Z note that cosmic ray energy density to galaxy-light is much larger than the ratio of cosmic rays to Galactic star-light. This, in their view, rules out an IGM or Early Universe explanation for cosmic rays and favors a Galactic origin for Cosmic Rays

  16. B&Z, noting the large velocity of blast waves, suggest that cosmic rays arise in supernovae • They compute the supernova energy injection rate and find that the resulting injection energy intensity to be comparable to the the intensity of cosmic rays • CONCLUSION 1: Cosmic rays arise from supernovae

  17. Conclusion 2:

  18. Palomar Observatory Museum 47

  19. First Astronomical Use of Schmidt Camera • The Schmidt design allows for wide field imaging with large aperture • The field of view of P48 is 47 square degrees! • Wider field can be obtained by lenses (cfRotse and others) • Modern wide field imagers use very complex cameras which require very fine alignment (not easy, cf PS-1, LSST)

  20. Motivating to the palomar transient factory

  21. P60 Confirmation P48 Discovery 200-inch 50

  22. Homework for serious students • Review the arguments presented in Baade & Zwicky (1934a) which led Baade & Zwicky to infer the explosion energy in supernovae to be between 1% and 100% of the rest mass of the Sun. Do you agree with the two analysis? What are the flaws? (or alternatively could there be SN with so much energy release).

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