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Attogram Dust Cloud a Million Kilometers from Comet Halley
Kissel, Jochen; Utterback, Nyle G.
Particle-impact ion mass spectrometers carried on the Giotto and two Vega spacecraft missions to Comet Halley in 1986 produced unexpected signals almost one million kilometers from Halley which can be attributed to high number densities of dust particles with masses of order 10 to the -18 g. The data imply that up to several percent of the total m…
The Ultraviolet and Visible Light Variability of BP Tauri: Possible Clues for the Origin of T Tauri Star Activity
Simon, Theodore; Vrba, Frederick J.; Herbst, William
BP Tau is a moderate-strength T Tauri star, which has previously been studied photometrically by Vrba et al. (1986, 1989) and shown to have a 7.6-day light cycle. Here, BP Tau was reobserved in order to monitor this star with the IUE satellite. In conjunction with the UV spectroscopy, nearly simultaneous ground-based optical photometry was also ob…
The IRAS Low-Resolution Spectra of Planetary Nebulae
Volk, Kevin; Cohen, Martin
This paper presents the low-resolution spectra of 170 planetary nebulae observed by IRAS, most of which were not included in the Atlas of Low-Resolution Spectra. These have been classified into eight groups based upon the spectral morphology, with emphasis on the dust continuum rather than the spectral lines. The Low-Resolution Spectrometer (LRS) …
Observations of SK -69 203 and the Interstellar Extinction Toward SN 1987A
Walborn, Nolan R.; Fitzpatrick, Edward L.
We have obtained optical and UV spectroscopic observations of the Large Magellanic Cloud (LMC) star Sk - 69^deg^ 203, which is located in the 30 Doradus region of the LMC, approximately 2.2 arcmin north of the position of SN 1987A. The optical data reveal Sk - 69^deg^ 203 to be a B0.7 Ia supergiant with a moderate nitrogen enhancement. The UV spec…
The Orbit and Companions of the Classical Cepheid FF AQL
Evans, Nancy Remage; Teays, Terry J.; Welch, Douglas L. +1 more
New radial velocities of the classical Cepheid FF Aql have been obtained and combined with previous observations to provide a revised orbit. A companion has been detected at 1800 A in IUE spectra with a spectral type of A9 V to F3 V. If the Cepheid has an evolutionary mass, then the mass ratio is M1/M2 = 3.8. A companion recently detected by speck…
A New Method to Determine the Interstellar Reddening toward WN Stars
Conti, Peter S.; Morris, Patrick W.
The emission lines in Wolf-Rayet stars may be utilized to determine the absorption properties of their line-of-sight interstellar medium. One can measure the line strengths both in terms of the equivalent widths (in units of the continuum) and fluxes. In general, in a comparison of two lines, the equivalent width ratio is extinction independent; i…
IUE Observations of WX Ceti in Outburst
Downes, Ronald A.
IUE observations of the peculiar dwarf nova WX Ceti roughly two weeks into a rare outburst, the first since 1963, are obtained. The SWP and LWP observations are very similar to other erupting dwarf novae, both in the line and continuum spectrum. The C IV 1549 A doublet displays blueshifted absorption, indicating the presence of a wind which has a …
Optical Variability of Extragalactic Objects Used to Tie the HIPPARCOS Reference Frame to an Extragalactic System Using Hubble Space Telescope Observations
Bozyan, Elizabeth P.; Hemenway, Paul D.; Argue, A. Noel
Observations of a set of 89 extragalactic objects (EGOs) will be made with the Hubble Space Telescope Fine Guidance Sensors and Planetary Camera in order to link the HIPPARCOS Instrumental System to an extragalactic coordinate system. Most of the sources chosen for observation contain compact radio sources and stellarlike nuclei; 65% are optical v…
Ultraviolet Colors as Age Indicators for LMC Clusters
Freeman, K. C.; Meurer, Gerhardt R.; Cacciari, C.
Empirical correlations are found between log ages (logτ) intrinsic ultraviolet colors C(18 - 31)_0_ and C(25 - 31)_0_ for 27 LMC clusters, where log τ is on the uniform age scale of Elson correlations as age indicators for LMC clusters and other stellar populations are discussed. The results are partially based on a new calibration of log τ vs the…
The Dynamical Mass of S MUSCAE
Cottrell, P. L.; Wallerstein, George; Bohm-Vitense, Erika +1 more
The amplitudes and phase relations of pulsational velocities of the Cepheid S Muscae, measured for lines originating at different atmospheric depths, are investigated. A mass M(A) = 4.4 + or - 0.5 solar masses is found for the Cepheid; however, the Cepheid is the evolved star and should have a mass larger than that of its companion. If the measure…