Search Publications
Disk-Overflow Accretion in GK Persei?
Hellier, Coel; Livio, Mario
We reanalyze the 1983 European X-ray Observatory Satellite (EXOSAT) observations of GK Per during an outburst to investigate the approximately 5000 s quasiperiodic modulation. We find that the spectral behavior is reminiscent of dipping low-mass X-ray binaries and note that the time scale is characteristic of the radius where an accretion stream o…
Ultraviolet Light Curves of beta Lyrae: Comparison of OAO A-2, IUE, and Voyager Observations
Kondo, Yoji; Polidan, Ronald S.; Eaton, Joel A. +3 more
The six-band ultraviolet light curves of beta Lyrae obtained with the Orbiting Astronomical Observatory (OAO) A-2 in 1970 exhibited a very unusual behavior. The secondary minimum deepened at shorter wavelength, indicating that one was not observing light variations caused primarily by the eclipses of two stars having a roughly Planckian energy dis…
Emission Lines in the Long-Period Cepheid L Carinae
Bohm-Vitense, Erika; Love, Stanley G.
For the Cepheid l Carinae, with a pulsation period of 35.5 days, we have studied the emission-line fluxes as a function of pulsational phase in order to find out whether we see chromospheric and transition-layer emission due to an outward-moving shock. All emission lines show a steep increase in flux shortly before maximum light, suggestive of a s…
The Hubble Space Telescope Extragalactic Distance Scale Key Project. II. Photometry of WFC Images of M81
Illingworth, Garth D.; Madore, Barry F.; Freedman, Wendy L. +11 more
The Extragalactic Distance Scale (H_0_) Key Project for Hubble Space Telescope (HST) aims to employ the Cepheid period-luminosity (P-L) relation to measure galaxy distances out as far as the Virgo Cluster. The vital steps in this program are (1) to obtain precise photometry of stellar images from the Wide Field Camera (WFC) exposures of selected g…
IUE Spectra and Optical Imaging of the Oxygen-rich Supernova Remnant N132D
Blair, William P.; Raymond, John C.; Long, Knox S.
We present new optical Charge Coupled Devices (CCD) interference filter imagery and International Ultraviolet Explorer (IUE) spectroscopy for the oxygen-rich supernova remnant N132D in the Large Magellanic Cloud. The optical images show a wealth of structure, and comparison with an archival Einstein High Resolution Imager (HRI) X-ray image shows t…
The Optical--Ultraviolet--Gamma-Ray Spectrum of 3C 279
Kazanas, D.; Ferland, G. J.; Browne, I. W. A. +6 more
We have obtained spectroscopy of the violently variable quasar 3C 279, simultaneous with γ-ray observations, in 1992 April. Our combined optical (McDonald Observatory and CTIO) and ultraviolet (HST) observations, made when the source was faint, show a very steep power-law continuum (Fnu_ is proportional to ν^-1.95^), and strong broad em…
The Nuclear Colors and Morphology of Field Galaxies at Moderate Redshift
Illingworth, Garth D.; Forbes, Duncan A.; Koo, David C. +2 more
Until recently, the study of faint field galaxies has been limited by the spatial resolutions available to ground-based imaging. Here we present HST images with 0-1 resolution for a sample of 203 field galaxies with I <= 22 (corresponding to B <= 24.5). The expected median redshift for such a sample is z ~ 0.5. The high resolution of HST all…
The He i lambda 10830 Line in Classical Cepheids. I. Observations
Sasselov, Dimitar D.; Lester, John B.
Using the Fourier Transform Spectrometer at the Canada-France-Hawaii telescope, we obtained high- resolution, high signal-to-noise ratio spectra of seven classical Cepheids at 1.08 µm. We report the first certain detection of the He I λ10830 line in Cepheids. Three of the Cepheids, X Sgr, η Aql, and ζ Gem, were observed with full phase cover…
The Pursuit of Heavy Elements in the HgMn-Type Star chi Lupi: Observations with the GHRS in the COSTAR ERA
Gilliland, Ronald L.; Lindler, Don J.; Wahlgren, Glenn M. +4 more
Observations of the ultra-sharp-lined HgMn star Chi Lupi made with the Goddard High Resolution Spectrograph (GHRS) after the Hubble Space Telescope (HST) First Servicing Mission display the effect of the Corrective Optics Space Telescope Axial Replacement instrument (COSTAR) upon the spectral resolution of several observing modes. The resolution i…
HST Observations of the [O iii] Emission-Line Region in Markarian 78
Boksenberg, A.; Capetti, A.; Sparks, W. B. +1 more
We present the results of HST observations of Mrk 78, a Seyfert 2 galaxy. Observations were taken with the Faint Object Camera using the F550M, F502M (which includes the [O III] λλ4959, 5007 emission lines), and F130M filters. These are medium band filters centered at 5500, 5020, and 1300 A, respectively. The [O III] image shows a biconical shape …