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Prediction and understanding of the north-south displacement of the heliospheric current sheet
Hoeksema, J. T.; Scherrer, P. H.; Zhao, X. P.
On the basis of Wilcox Solar Observatory observations of the photospheric magnetic field and the potential field-source surface model, we compare the solid angles occupied by the positive source surface field with that of the negative. We develop an algorithm to quantitatively estimate and understand the positive-negative displacement of the helio…
Polycyclic aromatic hydrocarbon emission bands in selected planetary nebulae: a study of the behaviour with gas phase C/O ratio
Barlow, M. J.; Cohen, Martin
Airborne and space-based low-resolution spectroscopy in the 1980s discovered tantalizing quantitative relationships between the gas phase C/O abundance ratio in planetary nebulae (PNe) and the fractions of total far-infrared (FIR) luminosity radiated by the 7.7- and 11.3-µm bands (the C = C stretch and C-H bend, respectively), of polycyclic …
The DEEP Groth Strip Survey. VIII. The Evolution of Luminous Field Bulges at Redshift z ~ 1
Weiner, Benjamin J.; Bouwens, Rychard J.; Gebhardt, Karl +12 more
We present a candidate sample of luminous bulges (including ellipticals) found within the Groth Strip Survey (GSS), with spectroscopic redshifts of 0.73<z<1.04 from the Keck Telescope. This work is distinguished by its use of two-dimensional two-component decomposition photometry from Hubble Space Telescope (HST) images to separate the bulge…
Supernova 1954J (Variable 12) in NGC 2403 Unmasked
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Challis, Peter M. +2 more
We have confirmed that the precursor star of the unusual supernova 1954J (also known as Variable 12) in NGC 2403 survived what appears to have been a superoutburst, similar to the 1843 Great Eruption of η Carinae in the Galaxy. The apparent survivor has changed little in brightness and color over the last 8 years, and a Keck spectrum reveals chara…
XMM-Newton spectroscopy of an X-ray selected sample of RL AGNs
Page, M. J.; Braito, V.; Caccianiga, A. +6 more
This paper presents the X-ray spectroscopy of an X-ray selected sample of 25 radio-loud (RL) AGNs extracted from the XMM-Newton Bright Serendipitous Survey (XBSS). The main goal of the work is to assess and study the origin of the X-ray spectral differences usually observed between radio-loud and radio-quiet (RQ) AGNs. To this end, a comparison sa…
Orientation and motion of two-dimensional structures in a space plasma
Hasegawa, H.; Sonnerup, B. U. Ã. -.
We present a new least squares technique for the determination of axis orientation, motion, and intrinsic axial electric field for two-dimensional coherent structures in a space plasma. This single-spacecraft method is based on Faraday's law, which, under the model assumptions, requires the intrinsic axial electric field to be constant in space an…
FUSE Measurements of Far-Ultraviolet Extinction. I. Galactic Sight Lines
Gordon, Karl D.; Sofia, Ulysses J.; Snow, Theodore P. +8 more
We present extinction curves that include data down to far-ultraviolet wavelengths (FUV; 1050-1200 Å) for nine Galactic sight lines. The FUV extinction was measured using data from the Far Ultraviolet Spectroscopic Explorer. The sight lines were chosen for their unusual extinction properties in the infrared through the ultraviolet; that they probe…
Metal Abundances in a Damped Lyα System along Two Lines of Sight at z = 0.93
Wisotzki, Lutz; Gregg, Michael D.; Lopez, Sebastian +3 more
We study metal abundances in the z=0.9313 damped Lyα system observed along the two lines of sight, A and B, toward the gravitationally lensed double QSO HE 0512-3329. Spatially resolved Space Telescope Imaging Spectrograph spectra constrain the neutral-gas column density to be N(HI)=1020.5 cm-2 in both A and B. UV-visual Eche…
The dynamic neptunian ring arcs: evidence for a gradual disappearance of Liberté and resonant jump of courage
de Pater, Imke; Macintosh, Bruce; Marchis, Franck +6 more
We present Adaptive Optics observations of Neptune's ring system at 1.6 and 2.2 µm, taken with the 10-m W.M. Keck II telescope in July 2002 and October 2003. We recovered the full Adams and Le Verrier rings for the first time since the Voyager era (1989), and show that the overall appearance of these rings did not change much, except for the…
Computing the reconnection rate at the Earth's magnetopause using two spacecraft observations
RèMe, H.; Owen, C. J.; Fuselier, S. A. +2 more
A new multispacecraft technique is introduced which, under some restrictive assumptions and conditions, provides a snapshot of the reconnection inflow velocity into the magnetosphere and an estimate of the distance from the spacecraft to the reconnection site. The two quantities are not obtained independent of one another and additional, independe…