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Central Star of NGC 3132: A Visual Binary

Published online by Cambridge University Press:  22 September 2016

L. Kohoutek
Affiliation:
Hamburg Observatory, Bergedorf, W. Germany
S. Laustsen
Affiliation:
European Southern Observatory, La Silla, Chile

Extract

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A faint companion to HD 87892 (V=10.07, B-V=+0.09, U-B=+0.10, Sp.A2) has been discovered with the 3.6 m telescope (prime focus) of the European Southern Observatory at La Silla having the following parameters: separation ψ = 1″.65, position angle θ = 226°.3. The companion was detected on plates taken in the U system (IIIa-J baked + UG1) and appears to be about ΔmU ≃ 4.5 mag fainter than the main component; it is almost invisible in the nearly visual system having Δmvis ≃ 4.8 mag. Contrary to the eccentric position of HD 87892 the companion lies in the axis of symmetry of the nebula. For the given reason the companion can be considered as the actual planetary nucleus. Assuming that its temperature is approximately T* ≈ 105 °K and the distance of the nebula d ≃ 0.9 kpc, the following parameters of the nucleus were estimated: L*/L ≃ 110, R*/R ≃ 0.035. The physical association of HD 87892 with its visual companion is probable. (Paper will appear in Astronomy and Astrophysics.)

Type
Session IV: The Central Stars of Planetary Nebulae
Copyright
Copyright © Reidel 1978