Search Publications
Comet Bowell 1980b
Feldman, P. D.; A'Hearn, M. F.; Schleicher, D. G. +2 more
The authors have carried out optical filter photometry and optical and ultraviolet spectrophotometry of Comet Bowell over the period November 1980 - June 1982. They have observed emission by OH at heliocentric distances to nearly 5 AU preperihelion with the OH emission implying a production rate which decreased, but with outbursts, as the comet ap…
VW HYI : the white dwarf revealed.
Szkody, P.; Mateo, M.
Nonsimultaneous IUE, optical, and near-IR observations of VW Hyi at quiescence are presented. Using these and UV data from other investigations, a broad feature in the ultraviolet is identified with L-alpha absorption. The presence and width of the line imply that (1) the white dwarf in VW Hyi is directly visible in the UV and (2) the effective te…
IUE spectroscopy of the degenerate components in the Hyades close binaries V471 Tauri and HZ 9.
Sion, E. M.; Guinan, E. F.
Effective temperatures and gravities have been determined for the degenerate components in the Hyades close binaries V471 Tauri and HZ9 from model atmosphere analysis of IUE ultraviolet spectra. For V471 Tauri, T(e) = 35,000 K and log g is about 8. For HZ9, T(e) = 20,000 K and log g = 8. Both systems contain DA2 white dwarfs. No photospheric metal…
Ripple correction of high-dispersion IUE spectra: blazing echelles.
Barker, P. K.
An iterative differential correcion technique designed to remove the blaze function of an echelle grating directly from observed spectral data is mathematically defined and applied to high-dispersion images acquired with the International Ultraviolet Explorer. Quantitative measurements of ripple correction accuracy demonstrate that the technique i…
The depletion of pre-interstellar matter and an examination of NI II oscillator strengths.
Cardelli, J. A.
IUE observations of the B2.5 V star α Sco B have been used to analyze the absorption lines that arise in the circumstellar shell around the M1.5 Iab star α Sco A. In addition to resonant lines of Fe II, Si II, Mg II, Mn II, and S II, most of the resonant lines of Ni II are also present at strengths above 40 mÅ. A fit of these Ni II lines to a curv…
The nature of radio-quiet QSO's VLA observations of 0026+129, 0205+024 and 1351+640.
Sitko, M. L.; Rudnick, L.; Stein, W. A.
VLA maps of 'radio-quiet' QSOs are reported. Extended emission is found on linear scales of about 10 kpc, larger than that observed in Seyfert galaxies, but smaller than most radio-loud objects. The spectral properties of some radio-quiet objects are also very similar to those of radio-quiet Seyfert galaxies such as NGC 4151; some radio-quiet QSOs…
The absorption near 1400 A in the spectra of additional DA white dwarfs.
Wegner, G.
Ultraviolet spectroscopic observations of five white dwarfs having published spectral types of DA made with the International Ultraviolet Explorer (IUE) satellite are reported. The three coolest objects: GD279 (0148 + 46), W485A (1327 - 08), and G231 - 40 (2117 + 53) have easily detected absorptions near lambda 1400. Of the two remaining stars, PG…
The distribution of interstellar matter toward Tycho's supernova remnant and its relation to distance estimates.
Raymond, J. C.; Black, J. H.
Observations of interstellar absorption lines in the spectra of five stars in the direction of Tycho's Supernova Remnant are presented. The profiles show significant absorption at large negative velocities, - 50 to - 60 km/s (LSR). This information, together with the distances of the background stars, permits limiting distances to be assigned to t…
NGC 3448 revisited : a combined optical, radio and UV investigation.
Casini, C.; Bertola, F.; Bettoni, D. +3 more
The present combined optical, radio, and UV observations are of the irregular galaxy NGC 3448. It interacts with a smaller spiral companion, UGC 6016, forming the peculiar system Arp 205. Rotation curves were constructed from the red lines of a KPNO spectrum and from VLA H I observations. Abnormal velocity features were detected, and are attribute…
A hot companion to MU Sagittarii : an opportunity to sound the atmosphere of a B8 IA supergiant.
Plavec, M. J.; Polidan, R. S.
It is argued that the bright supergiant star Mu Sagittarii is accompanied by a smaller and hotter star, of spectral type approximately B1.5 V. The single-line radial-velocity curve of the B8 star leads to a fairly large mass function, f(m) = 2.64 solar masses, implying that the companion should have at least 50 percent of the mass of the visible s…