Search Publications
Optical polarization of 1000 stars within 50 PC from the Sun
Leroy, J. L.
We have prepared a catalogue of optical polarization measurements for 1000 stars closer than 50 parsecs from the Sun. The distances, which are presently those given in the Sky Catalogue 2000.0, 2nd edition (Hirshfeld et al. 1991) are provisional: they will be replaced later by the much safer parallaxes which will result from the Hipparcos mission.…
A Spectroscopic and Photometric Study of FK Comae in 1989
Huenemoerder, David P.; Buzasi, Derek L.; Ramsey, Lawrence W. +1 more
Results of an observational campaign, coordinated between visual photometry, optical spectroscopy, and UV spectroscopy, to elucidate the characteristics of FK Comae are presented. The photometry showed complicated but systematic behavior. Photospheric absorption lines were distorted by a Doppler-shifted bump caused by dark starspots resulting in s…
Identification of ``small'' dust impacts in the Ulysses dust detector data
Grün, E.; Linkert, D.; Linkert, G. +2 more
Since October 1990, 3 weeks after the launch of the Ulysses spacecraft, the dust detector onboard recorded impacts of cosmic dust particles. Besides dust impacts, the detector recorded noise from a variety of sources. So far, a very rigid scheme had been applied to eliminate noise from impact data. The data labeled "big" dust impacts previously le…
Source characteristics of Jovian narrow-band kilometric radio emissions
Kaiser, M. L.; Desch, M. D.; Zarka, P. +5 more
New observations of Jovian narrow-bank kilometric (nKOM) radio emissions were made by the Unified Radio and Plasma Wave (URAP) experiment on the Ulysses spacecraft during the Ulysses-Jupiter encounter in early February 1992. These observations have demonstrated the unique capability of the URAP instrument for determining both the direction and pol…
Hubble Space Telescope Observations of Planetary Nebulae in the Magellanic Clouds. I. The Extreme Type I SMP 83/WS 35
Dopita, Michael A.; Ford, Holland C.; Evans, Ian N. +2 more
We have obtained Hubble Space Telescope Planetary Camera images in both the Hα and the [O III] λ5007 emission lines of the planetary nebula SMP 83 alias WS35, alias N66 in the Large Magellanic Cloud. By combining these results with optical and UV spectrophotometry, absolute flux measurements, and dynamical and density information, we have been abl…
A Giant X-Ray Flare on lambda Eridani (B2e)
Smith, Myron A.; Peters, Geraldine J.; Grady, Carol A. +1 more
A 30 ks observation with the ROSAT PSPC distributed over 39 hr shows that the putatively single, mild B2e star Lambda Eri emits at most times a soft X-ray flux at a rate and temperature consistent with other B stars. However, during the middle of our observations, this star's X-ray flux increased by a factor of 6 before returning to the basal leve…
The Ultraviolet Continua of Blazars: A Reconsideration of IUE Archives
Pian, E.; Treves, A.
The IUE archive data on blazars are reconsidered. They refer to 47 objects, 24 radio-strong BL Lac objects, 15 radio-weak BL Lac objects, and eight optically violently variable quasars, increasing substantially the sample examined by Ghisellini et al. (1986). For each object a dereddened spectral slope is evaluated starting from the extraction of …
Time-Series Observations of O Stars. III. IUE and HST Spectroscopy of zeta Ophiuchi and Implications for the ``Photospheric Connection''
Ebbets, D. C.; Bolton, C. T.; Prinja, R. K. +9 more
Stellar-wind variability in the archetypal nonradially pulsating O star ζ Oph (09.5 V) is discussed on the basis of new time-series lUE and HST spectroscopy and archival results. Time-variable "discrete absorption components" are first observed at high velocities (≳ 103 km s-1 ≃ 0.8υ∞) and then migrate blueward; th…
On the Interpretation of the Ultraviolet Spectra of Symbiotic Stars and Recurrent Novae. I.
Shore, Steven N.; Aufdenberg, Jason P.
We present an analysis of high-resolution spectra of several symbiotics and symbiotic novae. We show that the emission lines are severely affected by differential extinction caused by absorption lines in the wind of the red giant companion. The major source of the absorbing spectrum is the forest of lines produced by neutral and singly ionized iro…
NGC 4313. II. Hubble Space Telescope I-Band Surface Photometry of the Nuclear Region
Benedict, G. F.; Franz, O. G.; Hemenway, P. D. +11 more
We present a Hubble Space Telescope I-band Planetary Camera image of the nuclear region of NGC 4314. This is an anemic barred galaxy with recent star formation confined to a nuclear ring. These data resolve the nuclear ring into multiple sites of new star formation and resolve associated dust lanes into discrete clouds. Unsharp masking of a Lucy-R…