Search Publications
A Search for Interstellar CH2 toward HD 154368 and ζ Ophiuchi
Smith, Andrew M.; Bruhweiler, Frederick C.; Lyu, Cheng-Hsuan
We have searched for molecular CH2 in the interstellar gas in the line of sight to HD 154368 and ζ Oph to constrain further the gas-phase chemistry of carbon-bearing molecules in the cool, translucent clouds toward these stars. We report tentative detection of CH2 in the interstellar spectra of both stars. In ζ Oph, slight de…
Analysis of Stars Common to the IRAS and Hipparcos Surveys
Knapp, G. R.; Ivezić, Željko; Knauer, Timothy G.
For about 11,000 stars observed in the Hipparcos Survey and detected by IRAS, we calculate bolometric luminosities by integrating their spectral energy distributions from the B band to far-IR wavelengths. We present an analysis of the dependence of dust emission on spectral type and of the correlations between luminosity and dust emission for abou…
Mg II Emission Lines of Hyades F Stars
Robinson, Richard D.; Carpenter, Kenneth G.; Böhm-Vitense, Erika +1 more
With the Hubble Space Telescope (HST) we have observed Hyades F stars, using the Space Telescope Imaging Spectrograph (STIS), in order to get more information about the heating mechanism(s) for the chromospheres and transition layers and their dependence on rotation and age. In this paper we study the Mg II lines at 2800 Å. We include earlier obse…
Shock Wave Emission at Miller's Position 1 in the Cygnus Loop
Blair, William P.; Raymond, J. C.; Li, J. +1 more
We present the far-UV spectrum (900-1800 Å) of the bright filament known as Miller's (1974) position 1 in the Cygnus Loop obtained with the Hopkins Ultraviolet Telescope during the Astro-2 space shuttle mission. Longer wavelength IUE and ground-based spectra of adjoining regions were scaled to produce a combined spectrum ranging from 900 to 7500 Å…
Non-LTE Modeling of Nova Cygni 1992
Baron, E.; Hauschildt, Peter H.; Starrfield, S. +1 more
We present a grid of nova models that have an extremely large number of species treated in non-LTE and apply it to the analysis of an extensive time series of ultraviolet spectroscopic data for Nova Cygni 1992. We use ultraviolet colors to derive the time development of the effective temperature of the expanding atmosphere during the fireball phas…
Thermal Comptonization and Disk Thermal Reprocessing in NGC 3516
Chiang, James; Blaes, Omer
We present an application of the thermal Comptonization/disk reprocessing model recently proposed by Zdziarski, Lubiński, & Smith. We show that the absence of strong optical variations in the presence of strong concurrent X-ray variations, similar to those found by Hubble Space Telescope (HST)/Rossi X-Ray Timing Explorer (RXTE) monitoring obse…
Chemical Abundances of the Accreting Magnetic White Dwarf in the Polar AM Herculis
Sion, Edward M.; DePasquale, Joseph
We consider the presence of absorption lines due to accreted metals in the photosphere of the magnetic (28 MG) white dwarf in the prototype polar AM Herculis. We have applied the Massa-Fitzpatrick flux-calibration correction to the archival IUE NEWSIPS SWP spectra of AM Her obtained during the optical low states, when the accretion rate is very lo…
Where Are the Absorbers toward Q2302+029?
Bowen, David V.; Jenkins, Edward B.; Pettini, Max +1 more
We present images and spectroscopy of objects close to the sight line of Q2302+029 in order to search for galaxies responsible for the remarkable z=0.7 high-ionization absorption-line system found by Jannuzi et al. This system shows ``normal'' narrow O VI, N V, and C IV lines superimposed on broader (3000-5000 km s-1 wide), unsaturated …
Hipparcos and MAP Studies of the Triple Star π Cephei
Han, Inwoo; Gatewood, George; Pourbaix, Dimitri +2 more
We reexamine the visual and radial velocity data for the π Cephei triple star system and derive the masses of the three components. Our study is based upon the analysis of Hipparcos Intermediate Astrometric Data (IAD) measurements obtained with the red light Thaw refractor's Multichannel Astrometric Photometer (Thaw/MAP) and positions obtained fro…
An Empirical Procedure to Estimate Distances to Stellar Clusters
Allende Prieto, Carlos
A most desirable feature of a standard candle to estimate astronomical distances is robustness against changes in metallicity and age. It is argued that the radii of main-sequence stars with spectral types from solar to A0 show predictable changes with metallicity and detectable changes with evolution. Such stars populate the solar neighborhood an…