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A search for evolutionary changes in planetary nuclei: A continuationThis report summarizes the final results of an IUE investigation to search for signs of evolutionary changes in high-mass central stars of planetary nuclei, as evidenced by UV-optical fading over the lifetime of the satellite. The program is a continuation of an earlier investigation, expanding the target list to include more types of hot central stars and to obtain more spectra of previously observed stars. In order to compare the IUE fluxes of a central star obtained over a more-than-ten-year timespan, several steps were necessary, including reprocessing of very early spectra and correction for the sensitivity degradation of the SWP camera over time. The results indicate that while a few stars appear to have diminished UV fluxes compared to earlier IUE observations, the evidence for this is less than overwhelming due to the sparseness of the data. Those stars which emerge from this study as viable candidates for having faded are the cooler Of-type stars (O6f-O7f), i.e., those for which the change in spectral energy with increasing temperature is greatest. The report describes the data analysis steps and discusses the uncertainties in both the data and in the resulting fading rates. Estimates of stellar mass based on theoretical evolutionary rates are also provided.
Document ID
19960002337
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Altner, Bruce (Applied Research Corp. Landover, MD, United States)
Date Acquired
September 6, 2013
Publication Date
September 23, 1995
Subject Category
Astrophysics
Report/Patent Number
NASA-CR-199521
NAS 1.26:199521
ARC-R95-241
Accession Number
96N12345
Funding Number(s)
CONTRACT_GRANT: NASA ORDER S-97248-E
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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