Search Publications
The Nonhomologous Nature of Solar Diameter Variations
Basu, Sarbani; Sofia, Sabatino; Demarque, Pierre +2 more
We show in this Letter that the changes of the solar diameter in response to variations of large-scale magnetic fields and turbulence are not homologous. For the best current model, the variation at the photospheric level is over 1000 times larger than the variation at a depth of 5 Mm, which is about the level at which f-mode solar oscillations de…
Velocity field and star formation in the Horsehead nebula
Teyssier, D.; Güsten, R.; Hily-Blant, P. +1 more
Using large scale maps in C18O(2-1) and in the continuum at 1.2 mm obtained at the IRAM-30 m antenna with the Heterodyne Receiver Array (HERA) and MAMBO2, we investigated the morphology and the velocity field probed in the inner layers of the Horsehead nebula. The data reveal a non-self-gravitating (m/m_vir≈ 0.3) filament of dust and ga…
Absolute Proper Motion of the Canis Major Dwarf Galaxy Candidate
Rix, Hans-Walter; Peñarrubia, Jorge; Girard, Terrence M. +4 more
We have measured the absolute proper motion of the candidate Canis Major dwarf galaxy (CMa), at (l,b)=(240°,-8°). Likely main-sequence stars in CMa have been selected from a region in the color-magnitude diagram that has very little contamination from known Milky Way components. We obtain µlcosb=-1.47+/-0.37 and µb
Preliminary results on Saturn's inner plasmasphere as observed by Cassini: Comparison with Voyager
Coates, A. J.; Crary, F.; Johnson, R. E. +12 more
We present an analysis of Saturn's inner plasmasphere as observed by the Cassini Plasma Spectrometer (CAPS) experiment during Cassini's initial entry into Saturn's magnetosphere when the spacecraft was inserted into orbit around Saturn. The ion fluxes are divided into two sub-groups: protons and water group ions. We present the relative amounts of…
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…