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The Abell 35 Nebula Inside Out
Feibelman, W. A.; Hollis, J. M.; Pedelty, J. A. +3 more
We present deep 6 cm continuum and narrowband optical emission-line images in Hα λ6563, [O III] λ5007, [O II] λ3727, and [N II] λ6584 of the Abell 35 planetary nebula (PN), showing its unique features. First, surrounding the central binary system, there is a bow shock, best seen predominantly in [O III], possibly weakly in Hα, and not at all in [O…
A damped Lyα candidate at z~0.1 towards Q0439-433.
Petitjean, P.; Smette, A.; Theodore, B. +1 more
We report on the detection of a Z_gal_=0.101 galaxy projected on the sky at 4.2arcsec (or 5.2h^-1^_100_kpc for q_0_=0.5) from the quasar Q 0439-433 (z_em_=0.594). The HST spectrum of the quasar shows strong Mg II, Fe II, Si II, Al II and C IV absorption lines at the same redshift as the galaxy. The equivalent width ratios of the low ionization lin…
Seasonal Recession of Martian South Polar Cap: 1992 HST Observations
Clancy, R. Todd; James, Philip B.; Lee, Steven W. +2 more
The seasonal recession of the south polar cap of Mars has been studied using the Wide Field Planetary Camera images from Hubble Space Telescope obtained during the summer of 1992 when the angular size of Mars was between 5 and 6 arc sec. The observations cover the interesting period betweenLS= 259 and 284, when the recession is rapid an…
The Soft and Medium-Energy X-Ray Variability of NGC 5548: A Reanalysis of EXOSAT Observations
Tagliaferri, G.; Stella, L.; Treves, A. +2 more
We present a detailed cross-correlation (CCF) and power spectrum reanalysis of the X-ray light curves of the bright Seyfert 1 galaxy NGC 5548 obtained with EXOSAT. The 0.05-2 keV and 1-4 keV light curves are cross-correlated with the 1-9 keV and 4-9 keV light curves, respectively. We discuss how spurious time lags can be introduced by systematic e…
Langmuir waves associated with discontinuities in the solar wind: a statistical study.
Tsurutani, B. T.; Kellogg, P. J.; MacDowall, R. J. +2 more
We have reported previously that short bursts of Langmuir waves are frequently observed in the solar wind in isolated local depressions in the magnetic field magnitude, which are called "magnetic holes". The magnetic depression regions are often bounded by directional discontinuities (DDs). To study the relation between the waves and the discontin…
Modeling Emission Lines from Dwarf Novae in Quiescence
Kallman, Timothy R.; Lee, Y. Paul; Ko, Yuan-Kuen +1 more
For cataclysmic variables with disk accretion, it is plausible that X-rays/extreme-ultraviolet (EUV) radiation as a result of accretion can back-illuminate the accretion disk. Such illumination will photoionize and heat up the disk to form a temperature-inverted layer in which emission lines can form. We make self-consistent, non-LTE calculations …
The Spectrophotometric Variability of the Galactic Luminous Blue Variables AG Carinae and HR Carinae from 1978 to 1995
Shore, Steven N.; Altner, Bruce; Waxin, Isabelle
We present a long-term multiwavelength spectrophotometric study of two representative Galactic luminous blue variables (LBVs), AG Carinae and HR Carinae. We find that the assumption of bolometric constancy leads independently to an extinction of E(B-V)=0.65±0.05 mag for AG Car and 1.0±0.l mag for HR Car. We derive a luminosity for AG Car, of order…
Components of the ultraviolet continuum in active galactic nuclei.
Paltani, S.; Walter, R.
The ultraviolet spectral slope of individual active galactic nuclei (AGN), measured using IUE observations, varies considerably with time. Neither accretion disks nor optically thin emission models can explain these variations. We propose here a method based on the variability properties of these objects to disentangle various components of consta…
Detection of Low-Latitude Plumes in the Outer Corona by ULYSSES Radio Ranging Measurements
Woo, Richard
Low-latitude plumes have been detected beyond the field of view of coronagraphs in the range of 23--42 R0 in an equatorial coronal hole by Ulysses radio ranging measurements conducted in 1991 at 13 and 3.6 cm wavelengths. Exploiting the ranging measurement features of high sensitivity, wide dynamic range, high precision, high stability, and long d…
The ultraviolet polarization of the Crab pulsar
Lyne, A. G.; Dolan, J. F.; Boyd, P. T. +3 more
The linear polarization of the Crab pulsar has been observed in the ultraviolet using the High Speed Photometer on the Hubble Space Telescope. The polarization as a function of pulse phase is strikingly similar to that observed in the visible, with the same values of fractional polarization and the same swing of position angle occurring through th…