Search Publications
New Light Synthesis and Spectrum Synthesis Constraints on a Model for β Lyrae
Harmanec, P.; Hubeny, I.; Linnell, A. P.
A suite of programs that calculates both synthetic light curves and synthetic spectra for a binary system with an optically thick accretion disk has been applied for the first time to β Lyrae A. Our results demonstrate that the standard accretion disk model by Hubeny & Plavec shows significant residuals from observations, both photometric and …
Carbon and Oxygen Depletion and Extinction in the Translucent Cloud toward HD 24534 (X Persei)
Snow, Theodore P.; van Dishoeck, Ewine F.; Black, John H. +3 more
Recent studies of the gas-phase abundances of carbon and oxygen in diffuse clouds have suggested that the depletions of both elements are invariant and independent of extinction curve properties. We show, however, that in the line of sight toward HD 24534 (X Persei), the depletion of carbon is at least a factor of 3 greater than in the diffuse clo…
A test of B-type star Hβ photometric distances via the HIPPARCOS parallaxes
Knude, J.; Kaltcheva, N.
We test the photometric uvbybeta distances for B III, IV and V type stars, with an emphasis on the effect of rotation on the M_V determination. From the M_V(uvbybeta ) calibration of Balona & Shobbrook (1984), we have derived the absolute visual magnitudes for 176 stars with v sin (i) measurements and have compared them to M_V values derived v…
Mid-Infrared Emission Features in the Interstellar Medium: Feature-to-Feature Flux Ratios
Lu, Nanyao Y.
Using a limited but representative sample of sources in the interstellar medium of our Galaxy with published spectra from the Infrared Space Observatory, we analyze the flux ratios between the major mid-IR emission features (EFs) centered around 6.2, 7.7, 8.6, and 11.3 µm, respectively. In a flux ratio-to-flux ratio plot of EF(6.2 µm)/…
A Statistical Treatment of the Gamma-Ray Burst ``No Host Galaxy'' Problem. I. Methodology
Hartmann, Dieter H.; Band, David L.
If gamma-ray bursts originate in galaxies at cosmological distances, the host galaxy should be detected if a burst error box is searched deeply enough; are the host galaxies present? We present and implement a statistical methodology that evaluates whether the observed galaxy detections in a burst's error box are consistent with the presence of th…
CCD photometry of variable stars in the Magellanic Clouds - V. The eclipsing binaries HV1620 and HV2241
Guinan, E. F.; Pritchard, J. D.; Tobin, W. +1 more
Using improved techniques, high-quality CCD uvbyVI_C photometry has been obtained for the 14th magnitude eclipsing binaries HV1620 in the Small Magellanic Cloud (SMC) and HV2241 in the Large Magellanic Cloud (LMC). IUE ultraviolet spectrophotometry was also obtained. These data have been analysed using the Wilson & Devinney synthetic light-cur…
Correspondence between field aligned currents observed by Ulysses and HST auroral emission
Dougherty, M. K.; Dunlop, M. W.; Prange, R. +1 more
Auroral emission is direct evidence for the magnetophere/ionosphere coupling which exists for a magnetised planet such as Jupiter. This coupling takes place by way of momentum transfer which occurs via field aligned currents. The driving mechanism for the auroral emission is charged particle precipitation along the field lines. During the Ulysses …
The STIS Parallel Survey: Introduction and First Results
Ferguson, Henry C.; Baum, Stefi A.; Gardner, Jonathan P. +15 more
The installation of the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) allows for the first time two-dimensional optical and ultraviolet slitless spectroscopy of faint objects from space. The STIS Parallel Survey (SPS) routinely obtains broadband images and slitless spectra of random fields in parallel with HST obs…
Elemental Abundances in Coronal Structures
Kohl, John L.; Noci, Giancarlo; Raymond, John C. +1 more
A great deal of evidence for elemental abundance variations among different structures in the solar corona has accumulated over the years. Many of the observations show changes in the relative abundances of high- and low-First Ionization Potential elements, but relatively few show the absolute elemental abundances. Recent observations from the SOH…
A Long-Period Spectroscopic Binary in the O-Star Multiple System HD 193322
Bolton, C. T.; Fullerton, A. W.; Gies, D. R. +8 more
We present radial velocity measurements and a single-lined spectroscopic orbit for the bright O-type star, HD 193322A, which we show to be a 311 day binary system that has a distant third companion (detected by speckle interferometry) in a 31 yr orbit. We suggest that the speckle companion appears in the spectrum as a broad-lined component of earl…