Magnitudes of central stars in optically thick planetary nebulae

Journal Article · Wed Nov 01 04:00:00 EST 1989 · Astronomical Journal; (USA)

DOI:https://doi.org/10.1086/115252· OSTI ID:7144213

Jacoby, G H; Kaler, J B ^[1]

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1. Kitt Peak National Observatory, Tucson, AZ (USA) Illinois Univ., Urbana (USA)

Twenty planetary nebula central stars are observed with the goal of measuring accurate V magnitudes. These values are compared with the 'crossover' magnitudes predicted by Kaler and Jacoby (1989), which are computed from the nebular emission-line fluxes of He II 4686 A and H-beta. Many of these nebulae are dense and compact, and generate a strong nebular continuum that masks their nuclei. For ten of these, it is necessary to use nebular subtraction techniques developed by Jacoby (1988) and Heap and Hintzen (1990). In total, magnitudes are derived for 18 of these stars, and lower limits are set for the remaining two. For 14 nuclei, the magnitudes are measured with accuracies better than 0.25 mag, which appear to be superior to those generally available in the literature. In the remaining four cases, identifications and magnitude measurements are made at the detection limit and suffer from errors approaching 0.5 mag. It is found that the agreement between the predicted 'crossover' and observed magnitudes is very good for central stars in nebulae that are optically thick; the dispersion is only 0.5 mag. Thus, the use of the 'crossover' method to estimate the magnitudes and temperatures of obscured central stars is confirmed. This result implies that, at least for these hot stars, there is little evidence for a Zanstra discrepancy. Moreover, it justifies the use of the crossover technique for central stars of extra-galactic nebulae that are spatially unresolved, or to extremely faint central stars where conventional photometric methods become unreliable. 44 refs.

• OSTI ID: 7144213
• Journal Information: Astronomical Journal; (USA), Journal Name: Astronomical Journal; (USA) Vol. 98; ISSN 0004-6256; ISSN ANJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BALMER LINES
COMPARATIVE EVALUATIONS
DWARF STARS
EMISSION SPECTRA
ERRORS
LIMITING VALUES
LUMINOSITY
NEBULAE
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PLANETARY NEBULAE
SPECTRA
STARS
TEMPERATURE MEASUREMENT
WHITE DWARF STARS