Search Publications
First Results from the Goddard High-Resolution Spectrograph: Evidence for Photospheric Microturbulence in Early O Stars: Are Surface Gravities Systematically Underestimated?
Heap, S. R.; Hubeny, I.; Altner, B.
GHRS spectra of two very hot stars provide evidence for the presence of microturbulence in their photospheres. In attempting to reproduce the observed spectra, theoretical models have been built in which the microturbulence is allowed to modify not only the Doppler line widths (classical 'spectroscopic' microturbulence), but also the turbulent pre…
The Ultraviolet Spectrum and Continuum Energy Distribution of the Bright Quasar H1821+643
Filippenko, Alexei V.; Halpern, Jules P.; Kolman, Michiel +1 more
We report on the first UV observations of the bright QSO H1821+643. With V = 14.2 mag and z = 0.297, H1821+643 is the second brightest object in the sky at z > 0.1. The IUE data are combined with new optical spectroscopy, and existing infrared and X-ray data, to reveal a strong optical/UV "big bump," which continues past the Lyman limit in the …
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…
Multifrequency Observations of BL Lacertae in 1988
Kawai, N.; Matsuoka, M.; Chambers, K. C. +27 more
Simultaneous multiwavelength observations of BL Lacertae were performed on two occasions separated by 1 month in 1988 June and July, covering the radio, submillimeter, infrared, optical, ultraviolet, and X- ray wave bands. In the wide-band photon spectra, the X-ray flux lies clearly above the extension of radio-ultraviolet continuum as expected. T…
Observations of Solar Wind Ion Charge Exchange in the Comet Halley Coma
Balsiger, H.; Ip, W. -H.; Goldstein, B. E. +5 more
Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of Comet Halley. As the comet was approached, the He(2+) to proton density ratio increased from 2.5 percent in the solar wind to about 4 percent about 1 hr before close…
The Spacela-1 very wide field survey of UV-excess objects. II. Analysis of 7 stars of various nature.
Deleuil, M.; Bouchet, P.; Prevot, L. +2 more
Multiwavelength observations of seven stellar objects with strong UV excesses are presented. The observations are IUE spectrophotometry, Stromgren Vuvby optical photometry, Johnson JHK infrared photometry, intermediate resolution optical spectroscopy, and in one case a CORAVEL radial velocity survey. Three of the objects are field subdwarfs (one o…
First Results from the Goddard High-Resolution Spectrograph: C i, S i, and CO toward XI Persei and the Physical Conditions in Diffuse Clouds
Ebbets, Dennis C.; Savage, Blair D.; Lambert, David L. +5 more
Observations made by the Goddard High Resolution Spectrograph of the cool, neutral interstellar gas in the line of sight to Xi Per are reported. Heliocentric velocities and equivalent widths were measured for absorption lines of C I and S I. Synthetic spectra were computed and fitted to the observed CO(2-0) and (3-0) bands in the A IPi - X 1Sigma(…
Far-Ultraviolet Spectroscopy of the Quasar UM 675 with the Faint Object Spectrograph on the Hubble Space Telescope
Cohen, Ross D.; Burbidge, E. M.; Rosenblatt, E. I. +6 more
Observations of UM 675 with the HST and FOS demonstrate the proper functioning of the FOS. We detect light in UM 675 down to 520 A in the rest frame and set limits to He I emission, the He I Gunn-Peterson effect at z = 2.148, and Lyα absorption at z~0.5.
Stellar Photometry with the Hubble Space Telescope Wide-Field/Planetary Camera: A Progress Report
Schneider, Donald P.; Lauer, Tod R.; Faber, S. M. +16 more
We describe the prospects for the use of the Wide-Field/Planetary Camera (WFPC) for stellar photometry. The large halos of the point- spread function (PSF) resulting from spherical aberration and from spatial, temporal, and color variations of the PSF are the main limitations to accurate photometry. Degradations caused by crowding are exacerbated …
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…