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Hubble Space Telescope Ultraviolet Spectroscopy of the Highly Polarized but Quiescent Quasar OI 287
Kinney, Anne L.; Antonucci, Robert; Hurt, Todd
The quasar OI 287 has a unique combination of properties, including a high and constant optical polarization oriented parallel to the radio axis, a quiescent optical flux, and a lobe-dominant radio source. The polarization suggests a relationship to the broad absorption line quasars. It is a possible transition object which could illuminate the ge…
Optical and Hubble Space Telescope Ultraviolet Spectropolarimetry of 3C 273 and PG 1114+445
Schmidt, Gary D.; Smith, Paul S.; Allen, Richard G.
Ultraviolet polarization measurements of 3C 273 made with the Faint Object Spectrograph of the Hubble Space Telescope are combined with new optical spectropolarimetry and broad-band measurements made during occasions when the linear polarization of the quasar was <=1%. The HST measurements exhibit very weak UV polarization during the epoch of o…
Spectral analysis of LSE 78 : an extreme helium star similar to BD -9 4395 and DY Centauri.
Jeffery, C. S.
LSE 78 is a hydrogen-deficient early-B supergiant, spectroscopically similar to the pulsating extreme helium star BD - 9 deg 4395 and the hot R CrB star DY Cen. The photospheric parameters of LSE 78 have been derived from optical high-resolution spectra by the method of fine analysis. The principal results are Teff = 18000 K, log g = 2.…
The Optical Jet in Markarian 463
Ford, H. C.; Cohen, Ross D.; Evans, I. N. +4 more
Hubble Space Telescope images of Markarian 463, an interacting Seyfert 2 galaxy, reveal an optical jet 0.84 arcsec long at position angle PA~182^deg^ originating at the Seyfert nucleus. The jet terminates at a radio point source 1.2 arcsec from the nucleus. Previous polarization observations and our filter photometry suggests that the jet may be t…
Periodic Low Amplitude Variations in the Brightness of Proxima Centauri
Benedict, G. F.; Franz, O. G.; Hemenway, P. D. +10 more
Using data acquired with Fine Guidance Sensor #3 on board the Hubble Space Telescope we find that the brightness of Proxima Centauri varies with an amplitude of 0.01 magnitude and a period P=41.6 +/- 0.6 days. We interpret this variation as rotational modulation of star spots or bright regions in the photosphere of Proxima Centauri. In a total of …
Variability of the Seyfert galaxy MKN 766 in the ROSAT all sky survey.
Molendi, S.; Maccacaro, T.; Schaeidt, S.
Results are presented from the ROSAT All Sky Survey (RASS) observation of the Seyfert galaxy Mkn 766. Using a technique specifically developed for the analysis of point sources in the RASS we show that Mkn 766 is highly variable. Comparison of the soft X-ray spectrum (0.1-2 keV) with EXOSAT Medium Energy archive data (2-10 keV) clearly shows that …
The Ultraviolet Absorption Spectrum of the Quasar PKS 0405-12 and the Local Density of Lyman-Alpha Absorption Systems
Schneider, Donald P.; Jannuzi, Buell T.; Bahcall, John N. +1 more
A sample of 32 absorption lines has been identified in the ultraviolet spectrum of the z = 0.57 quasar PKS 0405 - 12. The observations were obtained using three R = 1300 gratings of the Faint Object Spectrograph of the Hubble Space Telescope. The data cover the wavelength range 1190- 3260 A. The sample was constructed by requiring that all include…
On the nature of the 25-min periodicity from 4U 0142+614 : a nearby, slowly spinning neutron star/Be system ?
Mereghetti, S.; Stella, L.; de Nile, F.
The unidentified X-ray source 4U 0142+614 has an unusually soft spectrum and has shown a periodic modulation at approximately 25 minutes, which could be interpreted as the orbital period of a Low Mass X-ray Binary. Recently a new X-ray source, probably a Be/neutron star system, has been discovered at an angular distance of only 24 arcmin from 4U 0…
JHK Photometry of WD 0950+139
Liebert, James; Fulbright, Michael S.
We present results from several nights of JHK photometry of the hot DA white dwarf 0950+139. It has a significant infrared excess over the expected flux from the white dwarf alone, confirming a previous finding by Zuckerman et al. (1991). The infrared excess corresponds to an upper limit on the spectral type of a companion of M4 V. We consider two…
Extreme Ultraviolet Observations of HZ 43 and the Local H/He Ratio with the Hopkins Ultraviolet Telescope
Feldman, Paul D.; Kimble, Randy A.; Davidsen, Arthur F. +1 more
We present a spectrum of the hot DA white dwarf HZ 43 in the EUV, near the 504-A ionization edge of neutral helium, obtained with the Hopkins Ultraviolet Telescope (HUT) during the 1990 December Astro-1 mission. The interstellar column densities derived from this spectrum rule out the anomalous interstellar absorption model proposed by Heise et al…