Search Publications
The Ultraviolet Spectrum of HH 24A and its Relation to Optical Spectra
Noriega-Crespo, A.; Brugel, E. W.; Boehm, K. H. +1 more
We have studied the spectrum of the brightest part (HH 24A) of the complex Herbig-Haro object HH 24 in the short wavelength (1300 A The ultraviolet spectrum is definitely detected in three observations with exposure times of 560 to 680 min. It is, however, sufficiently faint that corrections for the IUE "artifact spectrum" (as described by Crensha…
X-Ray Continuum with an Iron Emission Line from the Radio-Quiet Quasar PHL 909
Ghosh, K. K.; Soundararajaperumal, S.
Results of the spectral analysis of the X-ray (0.1 - 10 keV) spectrum of the radio-quiet quasar, PHL 909, are presented. A spectrum of this quasar which was observed on 1984/349, was obtained from the EXOSAT archives. Different models were used to fit the ME and LE+ME data. Fit parameters to the ME data show a steep spectral index for this quasar …
Ultraviolet Colors of Old LMC Clusters
Cowley, A. P.; Hartwick, F. D. A.
New ultraviolet spectra for five red LMC globular clusters have been obtained with IUE. These have been supplemented with archival spectra for eleven old LMC clusters. These data strengthen and extend the UV-color vs. age relation for clusters older than 10^9 years, but do not offer much precision in age determination, presumably because the ultra…
The Composite Nature of the Peculiar Star HR 6560 (HD 159870)
Wegner, Gary; Cowley, Charles R.
Ground based high dispersion photographic spectra and ultraviolet spectra obtained with the International Ultraviolet Explorer (IUE) satellite are described and employed to determine the nature of the peculiar star HR 6560 (HD 159870). Previously this object had been described as both a composite system and a strong Fm star. We inter-compare the U…
Weighted Slit Extraction of Low-Dispersion IUE Spectral Data
Bohlin, R. C.; Kinney, A. L.; Neill, J. D.
standard extraction for low-dispersion spectra in the final IUE archives. In order to properly weight the data within the extraction slit and obtain the optimal evaluation of the true spectrum, a noise model is derived for IUE data. The exclusion of cosmic rays is demonstrated and the improvement in signal-to-noise ratio is quantified for spectra …
PB 6 and Its Central Star
Feibelman, Walter A.; Shaw, Richard A.; Kaler, James B. +1 more
It is found that the hot nucleus of the Type I southern planetary nebula PB 6 is a member of the rare class of O VI stars. The blended O VI 3811 + 3834 emission doublet is one of the strongest seen, with an equivalent width (relative to the stellar continuum) of about 400 A. The helium, nitrogen, and carbon abundances are all very high for the cor…
The Halo Planetary Nebulae M 2-29 and BB-1
Pena, M.; Torres-Peimbert, S.; Ruiz, M. T.
Spectrophotometric data for the two planetary nebulae are given and compared to the data for a well-understood type of planetary nebula (PN) for classification and measurements of abundances. M 2-29 and BB-1 were observed in the wavelength ranges of 3500-5000 and 6000-7500, and the visual calibrated spectra and emission-line fluxes are given along…
Hubble Space Telescope Images and Follow-Up Spectroscopy of the Orion Nebula
O'Dell, C. R.; Wen, Zheng; Hester, J. J.
Recently published HST images of the Orion nebula reveal elephant-trunk structures, an apparent jet of material, and fine-scale structure in the Herbig-Haro object HH2, which is located at the base of an elephant trunk. High-resolution spectroscopy shows that the apparent jet is actually an ionization front seen edge-on. HH2 shows a complex struct…
Life at the Edge: Emission From the H II Region/Photodissociation Region Interface
Hester, J. J.
Preliminary results of an imaging survey of Galactic H II regions are presented and discussed with respect to the character of low-ionization potential lines and the structure of the H II region/photodissociation region (PDR) interface. A model of (S II) emission is developed according to the preliminary results and the interpretation of the struc…
Carbon in Orion
Walter, D. K.
The carbon abundance in the Orion nebula is redetermined from a detailed study of UV spectra in the IUE archives. Temperature and electron density gradients were derived for the inner 5 arcmin of the nebula using new and existing observational data. These temperatures and densities were used to calculate the carbon abundance for 19 positions large…