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The Supergiant Binary BM CAS
Evans, N. R.; Fernie, J. D.
Attracted by an earlier claim (Thiessen 1956) that BM Cas is an eclipsing binary with one component a classical Cepheid, we have obtained new photometry and IUE ultraviolet spectra of the system. While we verify that there is variability in addition to the eclipses, we conclude that there is no classical Cepheid present. The variability is irregul…
A Reassessment of the IUE Emission Line Spectrum of the Planetary Nebula NGC 5189 and Its Central Star
Feibelman, W.
Archival high-and low-dispersion IUE spectra of NGC 5189 and its central star were reexamined. It was found that earlier published results misinterpreted nebular features for stellar emission lines due to incorrect coordinates and/or incorrect pointing of the spacecraft. NGC 5189 has a UV spectrum rich in emission lines of He II, C II], C III, C I…
Parallaxes and Proper Motions of Prototypes of Astrophysically Interesting Classes of Stars. I. R Coronae Borealis Variables
Kundu, Arunav; Trimble, V.
Hipparcos data were obtained under the 1982 announcement of opportunity for the seven brightest R CrB stars then known. None of the parallax measurements is different from zero in a statistically significant way, though most of the proper motions are. The body of the data nevertheless suggest that the stars belong to two rather different populatio…
A New Color Image of the Crab Nebula
Wainscoat, R. J.; Kormendy, J.
A new color image of the Crab Nebula is presented. This is a 2782 × 1904 pixel mosaic of CCD frames taken through B (blue), V (green), and R (red) filters; it was carefully color balanced so that the Sun would appear white. The resolution of the final image is approximately 0.8 arcsec FWHM. The technique by which this image was constructed is desc…
Near Infrared Imaging of the Proposed z=2 Cluster Behind CL 0939+4713 (Abell 851)
Hutchings, J. B.; Davidge, T. J.
We have obtained deep J and K' images of a 90 arcsec square field containing the z=2.0 QSO that is viewed through the z=0.4 rich cluster A851. Brightnesses of individual galaxies are measured from these data, and archival F702W WFPC2 images from HST. The results are used to construct 2-colour diagrams, colour-magnitude diagrams, and luminosity fun…
HIPPARCOS Astrometry of Infrared-Selected Sources and the Connection Between Optical and Infrared Reference Frames
Sutton, E.
Astrometric data from the Hipparcos satellite are reported for the optical counterparts of 87 bright infrared sources. These sources may be useful in defining a reference frame for infrared observations. The data are also useful in studying the locations of circumstellar SiO masers. (SECTION: Stars)
On the Automatic Determination of Light-Curve Parameters for Cepheid Variables
Stetson, Peter B.
A computerized algorithm for the automatic detection of Cepheid variables and for the estimation of their periods, amplitudes, and mean magnitudes from sparse data sets is presented. It is intended to be suitable for use in such programs as the measurement of Cepheid distances to external galaxies, for example with the Hubble Space Telescope. The …
A Database for Galaxy Evolution Modeling
Walborn, Nolan R.; Parker, Joel Wm.; Robert, Carmelle +77 more
This paper represents a collective effort to provide an extensive electronic database useful for the interpretation of the spectra and evolution of galaxies. A broad variety of empirical and theoretical data are discussed here, and the data are made fully available in the AAS CD-ROM Series, Vo. 7. Several empirical stellar libraries are part of th…
A Supergiant-Dominated Starburst in the Nucleus of NGC 4569
Keel, William C.
The Virgo spiral NGC 4569 has a very compact optical nucleus whose spectrum is highly composite, which strong Balmer absorption indicating that A stars dominate the optical light. Recent HST imaging shows that the nucleus is extremely compact in the mid-ultraviolet, so that either there must be a central AGN or an extraordinarily luminous and comp…
The Spectrum of the Planetary Nebula NGC 6790
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H.
International Ultraviolet Explorer (IUE) and optical region spectroscopic observations are presented for the medium excitation planetary nebula (PN), NGC 6790, which displays a rich spectrum permitting application of several diagnostic ratios and the calculation of a number of ionic concentrations, N(ion)/N(H+). NGC 6790 seems to be a relatively y…