| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
We made optical observations of close binary central stars of planetary nebulae in order to obtain reliable physical quantities of central stars. Relating to the evolution of main- sequence close binaries toward binary central stars of planetary nebulae, we also studied close binaries on or near the main sequence.
Among central stars of planetary nebulae, we made optical spectroscopic and photometric observations of three close binary central stars, LT-5, HFG1, and UU Sge, using the 188-cm and 91-cm telescopes at Okayama and Dodaira Observatories of National Astronomical Observatory of Japan (NAOJ). We also analyzed data taken at Mauna Kea Observatory using University of Hawaii 224-cm and 61-cm telescopes (supported by the Grants-in-Aid for Overseas Scientific Research [Head Investigators: Prof. T. Kogure (1988) and Prof. T. Tsuji (1989)] of the Ministry of Education, Science, and Culture).
LT-5: it was found that (a) the G-star rotates with a period of 1.200 days; (b) the G-star and its close companion form an inner system with the orbital period of 1.755 days; (c) the existence of a third body (a hot star which excites the nebula) is deduced from the change of systemic velocities with a period of - 2000 days (an outer system). Physical quantities of the component stars are discussed. H. L. Malasan, graduate student, analyzed the data and presented MSc Thesis.
HFG1: we obtained an almost complete light curve, confirming the discovery by Grauer et al. We interpreted the variation of light by the reflection effect and obtained a preliminary model for the binary central star system.
UU Sge: we obtained for the first time a radial velocity curve, and discussed physical quantities of the system.
We analyzed three main-sequence/post-main-sequence binaries, delta Cap, UZ Pup, and DD Mon; deduced physical quantities of components; and discussed briefly their binary evolution.
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