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The Central Star of NGC 7027

Published online by Cambridge University Press:  19 July 2016

N.A. Walton
Affiliation:
Kapteyn Laboratorium, Groningen, The Netherlands
S.R. Pottasch
Affiliation:
Kapteyn Laboratorium, Groningen, The Netherlands
N. K. Reay
Affiliation:
Queensgate Instruments Ltd., Sunbury, Great Britain
T. Spoelstra
Affiliation:
Radiosterrenwacht Dwingeloo, The Netherlands

Abstract

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We have detected the central star of NGC 7027 by imaging the nebula through a narrow band ‘continuum’ filter onto the IPCS detector at the 2.5m Isaac Newton Telscope. We obtain an apparent visual magnitude for the central star of mv = 17.7 ± 0.5 mags.

Assuming that the central star radiates approximately as a blackbody, which is reasonable for the case of a hot star, then Zanstra temperatures for the central star can be calculated. We find TZ(H) = 3.9 × 105K and Tz(HeII) = 2.6 × 105K. Using the correction due to Stasinska & Tylenda (1986) we estimate the central star of NGC 7027 to have a temperature, Teff = 3.1 × 105K.

The luminosity and radii are found assuming a distance of d=1.2 kpc., giving L = 12,600 L and R = 0.039 R. Placing the central star on the Log L - Log T diagram and comparing with evolutionary tracks for central stars with various masses from Wood & Faulkner (1986), indicates that the central star of NGC 7027 must have a mass, M ≥ 0.8 M.

Radio observations of NGC 7027 have been taken using the Westerbork Radio Synthesis Telesocpe at 21cm. Self calibration techniques have been employed to give a radio continuum map of high dynamic range. These observations are being compared with a deep optical Hβ map to study the nature of the faint halo seen around NGC 7027 (Atherton et al. 1979)

Type
III. Central Stars
Copyright
Copyright © Kluwer 1989 

References

Atherton, P.D., Hicks, T.R., Reay, N.K., Robinson, G.J., Worswick, S.P., Phillips, J.P.: 1979, Astron. Astrophys. 232, 786 Google Scholar
Stasinska, G., Tylenda, R.: 1986, Astron. Astrophys. 155, 137 Google Scholar
Wood, P.R., Faulkner, D.J.: 1986, Astrophys. J. 307, 659 CrossRefGoogle Scholar