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Theory of Evolution of the Central Star

Published online by Cambridge University Press:  22 September 2016

Giora Shaviv
Giora Shaviv*
Affiliation:
Department of Physics and Astronomy Tel-Aviv University, Ramat-Aviv, Israel

Extract

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The fundamental feature of the evolution of the central star of planetary nebulae (CPN) is the cooling of the core towards a white dwarf. The basic observations were made by O'Dell (1963), Seaton (1966), and Harman and Seaton (1964); namely, they discovered a correlation between the linear size of the nebula and the position of the CNP in the HR diagram. Typical values for the velocity of expansion are 10–30 km/sec and the largest size observed for a nebula is ∼0.6 pc and hence the lifetime is 2–6 × 104 years. From a theoretical point of view the important fact about the Harman-Seaton sequence (HS) is the implication on the evolution of the central star. The star first heats up, L and Te increase, then L decreases. But Te keeps increasing until finally Te decreases also (shown schematically in Figure 2). Thus the HS is an evolutionary sequence and not a locus of stars.

Type
Session IV: The Central Stars of Planetary Nebulae
Information
Symposium - International Astronomical Union , Volume 76: Planetary Nebulae , 1978 , pp. 195 - 199
Copyright
Copyright © Reidel 1978 

References

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