Search Publications
A Search for Stellar Flares in Gamma-Ray Bursts Observed by BATSE and ULYSSES
Hurley, K.; Fishman, G. J.; Kouveliotou, C. +2 more
We have searched for gamma-ray bursts during stellar flares using Ulysses and BATSE/CGRO data and for a correlation between flare star positions and burst positions. More than 3000 stellar flares have been identified optically, but neither BATSE nor Ulysses observed any gamma-ray bursts which could be attributed to them. Using the BATSE trigger th…
Radiation Hydrodynamic Models of Eclipsing Low-Mass X-Ray Binaries
McKee, Christopher F.; Murray, Stephen D.; Woods, D. Tod +2 more
We present the results of self-consistent two-dimensional radiation hydrodynamic models of winds and coronae above accretion disks in low-mass X-ray binaries. The numerical method combines adaptive mesh refinement for the hydrodynamics with combined ray tracking/flux-limited diffusion for the radiation. The results of the models are compared with …
Tomography/Power Spectrum Techniques for Removal of Fixed Pattern Noise from Hubble Space Telescope Spectra
Smith, Andrew M.; Bruhweiler, Frederick C.; Lyu, Cheng-Hsuan
We have developed tomography/power spectrum algorithms to differentiate the intrinsic stellar spectrum from the pronounced fluctuations in the spectrum counts due to photocathode granularity and diode-to-diode gain variations. We have presented the results of four typical high signal-to-noise (S/N) and high-resolution data sets, obtained from the …
Hubble Space Telescope Imaging of the Wind-blown Lobe NGC 6165
O'Neil, Earl J., Jr.; Scowen, Paul; Lynds, C. Roger +3 more
We have used the Hubble Space Telescope wide field/planetary camera to study the structure of the bipolar nebular NGC 6164/6165. Our study concentrates on the structure of a number of small clumps of material embedded within the southern lobe of the system (NGC 6165). These knots have a cometary appearance, with bright surfaces facing the central …
The Faint Limit of the Hubble Space Telescope Faint Object Spectrograph and Rejection of the Cosmic-Ray Background
Tytler, David; Davis, Christopher
The faintest object which can be observed with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) is set by the detector cosmic-ray background and not by object flux. We use data from Beaver and Lyons to show that 48% of the background counts are from cosmic rays which each generate a near instantaneous burst of two or more counts. S…
Dust Extinction of the Stellar Continua in Starburst Galaxies: The Ultraviolet and Optical Extinction Law
Calzetti, Daniela; Storchi-Bergmann, Thaisa; Kinney, Anne L.
We analyze the IUE UV and the optical spectra of 39 starburst and blue compact galaxies in order to study the average properties of dust extinction in extended regions of galaxies. The optical spectra have been obtained using an aperture which matches that of IUE, so comparable regions within each galaxy are sampled. The data from the 39 galaxies …
R v-dependent Optical and Near-Ultraviolet Extinction
O'Donnell, James E.
We have derived extinctions A(lambda)/A(V) at the wavelengths of the uvby filters for 22 stars, with a range of values of Rnu, from the sample of Cardelli, Clayton, & Mathis (1989, hereafter CCM). We have fit these extinctions, and also UBVRIJHKL, IUE and ANS extinction measurements, with linear relations A(lambda)/A/(V) = a+b/R
The Hubble Space Telescope Extragalactic Distance Scale Key Project. I. The Discovery of Cepheids and a New Distance to M81
Illingworth, Garth D.; Kennicutt, Robert C.; Madore, Barry F. +12 more
We report on the discovery of 30 new Cepheids in the nearby galaxy M81 based on observations using the Hubble Space Telescope (HST). The periods of these Cepheids lie in the range of 10-55 days, based on 18 independent epochs using the HST wide-band F555W filter. The HST F555W and F785LP data have been transformed to the Cousins standard V and I m…
HST FOS Spectroscopy of M87: Evidence for a Disk of Ionized Gas around a Massive Black Hole
Kriss, Gerard A.; Hartig, George F.; Ford, Holland C. +7 more
Using the Faint Object Spectrograph on the Hubble Space Telescope (HST) to observe the central region of M87, we have obtained spectra covering ~4600-6800 A at a spectral dispersion ~4.4 A per resolution element through the 0.26" diameter entrance aperture. One spectrum was obtained centered on the nucleus of M87 and two centered 0.25" off the nuc…
Postrefurbishment Mission Hubble Space Telescope Images of the Core of the Orion Nebula: Proplyds, Herbig-Haro Objects, and Measurements of a Circumstellar Disk
O'Dell, C. R.; Wen, Zheng
We report on observations of M42 made with the Hubble Space Telescope (HST) immediately after the successful repair and refurbishment mission. Images were made in the strongest optical emission lines of H I, (N II), and (O III) and in a bandpass close to V. In a previous paper, the term proplyd was introduced to describe young stars surrounded by …