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Kaler, J. B.

Publications and source records attributed to Kaler, J. B..

9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Ultraviolet spectra of the central stars of large planetary nebulae

The ultraviolet spectra of 32 planetary nebula nuclei have been examined with the IUE. Ultraviolet and UV-to-optical flux ratios are derived, from which color temperatures are derived. The distribution of the latter ranges from rough agreement with the Zanstra temperatures upward to infinite values. The high-luminosity stars have generally lower, determinable color temperatures; the infinite or indeterminable color temperatures are contained by the set of lower luminosity stars. About half the stars exhibit a mixture of line features, most commonly He II 1640 A and C IV 1550 A in emission or absorption. Three display clear P Cygni lines, while a fourth appears to display a remarkably broad C IV 1550 A P Cygni profile. The other half of the stars have no perceptible line features.

Kaler, J. B.↗
NASA NTRS1985

The nature of Weinberger-12

From IUE spectra of its central star, it is concluded that Weinberger-12 is a small H II region, and not a planetary nebula. The star is substantially reddened with a color excess of 0.75 m, is most likely a B0.5-B1 giant or subgiant about three kpc distant, and possibly belongs to the Cas OB2 association.

Kaler, J. B.↗
NASA NTRS1985

Wind distances for planetary nebulae

A new method for the determination of distances to planetary nebulae is presented. If a star has a strong wind that produces a P Cygni profile in its spectrum, an escape velocity may be inferred from the terminal velocity, which provides a relation involving stellar temperature, luminosity, and mass. The theory of stellar evolution provides a second relation among these three variables, so that once the star's temperature is known, it is possible to simultaneously derive its mass and luminosity, and hence its distance. The method is applied to several test cases that illustrate its viability and current limitations.

Kaler, J. B.↗
NASA NTRS1984

The central star of the planetary nebula Abell 78

The ultraviolet spectrum of the nucleus of Abell 78, one of the two planetaries known to contain zones of nearly pure helium, is studied. The line spectrum and wind velocities are examined, the determination of interstellar extinction for assessing circumstellar dust is improved, and the temperature, luminosity, and core mass are derived. The results for A78 are compared with results for A30, and it is concluded that the dust distributions around the two central stars are quite different. The temperature of the A78 core is not as high as previously believed, and almost certainly lies between 67,000 K and 130,000 K. The most likely temperature range is 77,000-84,000 K. The core mass lies between 0.56 and 0.70 solar mass, with the most likely values between 0.56 and 0.58 solar mass.

Kaler, J. B.↗
NASA NTRS1983

The binary central star of the planetary nebula LT-5

Data from the IUE shows that the true central star of the giant planetary Longmore-Tritton 5 (339+88.1 deg) is a binary companion to the G5 star SAO 82570. The slope of the energy distribution curve indicates that the star may be one of the hottest known. The Mg II doublet associated with the G star is very strong, consistent with the existence of a close binary companion.

Feibelman, W. A.↗