Search NASA⌕ Search

Engineering topics

Haramundanis, K. L.

Publications and source records attributed to Haramundanis, K. L..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Interstellar extinction in the ultraviolet from emission stars

Since many of the analyses of interstellar extinction in the ultraviolet depend on observations of stars with emission lines, it is important to know whether the slope of the reddening line is on the average the same for normal stars and for emission stars. An investigation of normal and emission stars ranging in spectral class from O5 to O9 (as observed by the Celescope experiment on board OAO 2) indicates that normal and emission O stars do not have the same average color-excess ratio and that this characteristic is particularly prominent at 2300 A. This implies that interstellar extinction in the ultraviolet cannot be mapped unambiguously by using O stars unless all those in the sample are known not to be emission-line objects.

Haramundanis, K. L.↗
NASA NTRS1973

Investigation of ultraviolet interstellar extinction

Results concerning interstellar extinction in the ultraviolet are reported. These results were initially obtained by using data from main-sequence stars and were extended to include supergiants and emission stars. The principal finding of the analysis of ultraviolet extinction is not only that it is wavelength dependent, but that if changes with galactic longitude in the U3 passband (lambda sub eff = 1621 A); it does not change significantly in the U2 passband (lambda sub eff = 2308 A). Where data are available in the U4 passband (lambda sub eff = 1537 A), they confirm the rapid rise of extinction in the ultraviolet found by other investigators. However, in all cases, emission stars must be used with great caution. It is important to realize that while extinction continues to rise toward shorter wavelengths in the ultraviolet, including the shortest ultraviolet wavelengths measured (1100 A), it no longer plays an important role in the X-ray region (50 A).

Payne, C.↗
NASA NTRS1973

Celescope catalog of ultraviolet stellar observations: 5068 objects measured by Orbiting Astronomical Observatory (OAO-2)

During the 16 months that the Celescope Experiment operated, it took 8000 frames of data. This report describes the experiment, the data it gathered, the format of the magnetic tape containing the data, and a number of programs that were written to read and manipulate the tape. The tape version of the catalog contains Data on 5068 stars and is available from the National Space Sciences Data Center.

Davis, R. J.↗
NASA NTRS1973

Investigation of ultraviolet interstellar extinction

The progress made during the past six months in utilizing Celescope OAO-2 data in a study of extinction is reported along with conclusions drawn from each inquiry. Areas recommended for further investigation are indicated.

Payne-Gaposchkin, C.↗
NASA NTRS1973

Celescope catalog of ultraviolet stellar observations

The catalog contains the observational results obtained by the Celescope Experiment during the first 16 months of operation of NASA's Orbiting Astronomical Observatory (OAO-2). It lists the results of the stellar observations, along with selected ground-based information obtained from the available literature. Lunar observations (Ahmad and Deutschman, 1972), as well as other analyses of the data, are being published as separate papers. These data are available in two forms: (1) magnetic tapes and the necessary utility programs for reading and printing the contents of the tapes; and (2) this catalog, transcribed from the magnetic-tape catalog. The magnetic tape version contains not only the compiled results but also the results of the individual observations from which these averaged data were compiled.

Davis, R. J.↗