Search Publications
On the intensity and spatial morphology of the 511 keV emission in the Milky Way
Prantzos, N.
The positron emissivity of the Galactic bulge and disk, resulting from radioactivity of SNIa, is reassessed in the light of a recent evaluation of the SNIa rate. It is found that the disk may supply more positrons than required by recent observations, but the bulge (where the characteristic e+ annihilation line at 511 keV is in fact obs…
The Deceleration of an Interplanetary Transient from the Sun to 5 Au
Tappin, S. J.
A CME which was first seen in LASCO is tracked through SMEI and on out to Ulysses. These measurements allow us to determine the deceleration and compare different models of the deceleration process. It is found that both a simple "snow plough" model and an aerodynamic drag model predict a much more rapid deceleration in the lower solar wind than i…
Luminosity function of contact binaries based on the All Sky Automated Survey (ASAS)
Rucinski, Slavek M.
The luminosity function for contact binary stars of the W UMa type is evaluated on the basis of the All Sky Automated Survey (ASAS) photometric project covering all stars south of δ=+ 28° within a magnitude range 8 < V < 13. Lack of colour indices enforced a limitation to 3374 systems with P < 0.562 d (i.e. 73 per cent of all systems with…
Mass along the Line of Sight to the Gravitational Lens B1608+656: Galaxy Groups and Implications for H0
McKean, J. P.; Fassnacht, C. D.; Readhead, A. C. S. +3 more
We report the discovery of four groups of galaxies along the line of sight to the B1608+656 gravitational lens system. One group is at the redshift of the primary lensing galaxy (z=0.631) and appears to have a low mass, with eight spectroscopically confirmed members and an estimated velocity dispersion of 150+/-60 km s-1. The three othe…
Oscillatory magnetic flux tube slippage in the plasma sheet
Petrukovich, A. A.; Balogh, A.; Zhang, T. L. +4 more
Cluster observations in the magnetotail revealed an abundance of strongly inclined current sheets. We determine the magnetic configuration of a particular subset of such phenomena: a series of sheet crossings, having significantly differing inclinations and occurring during quiet conditions. These wave-like variations appear to propagate azimuthal…
Dissipation of Titan's south polar clouds
Brown, Michael E.; Trujillo, Chadwick A.; Bouchez, Antonin H. +2 more
Nearly all adaptive optics images of Titan taken between December 2001 and November 2004 showed tropospheric clouds located within 30° of the south pole. We report here on a dissipation of Titan's south polar clouds observed in twenty-nine Keck and Gemini images taken between December 2004 and April 2005. The near complete lack of south polar clou…
The Rate of Type Ia Supernovae at High Redshift
Tonry, John L.; Barris, Brian J.
We derive the rates of Type Ia supernovae (SNe Ia) over a wide range of redshifts using a complete sample from the IfA Deep Survey. This sample of more than 100 SNe Ia is the largest set ever collected from a single survey and therefore uniquely powerful for a detailed supernova rate (SNR) calculation. Measurements of the SNR as a function of cosm…
VLT/GIRAFFE spectroscopic observations of the metal-poor blue compact dwarf galaxy SBS 0335-052E
Schaerer, D.; Royer, F.; Izotov, Y. I. +3 more
Aims.We present two-dimensional spectroscopy of the extremely metal-deficient blue compact dwarf (BCD) galaxy SBS 0335-052E to study physical conditions, element abundances and kinematical properties of the ionised gas in this galaxy.
Methods: .Observations were obtained in the spectral range λ3620-9400 Å with the imaging spectrograph GIRAFFE …
The electrostatic potential of E ring particles
Beckmann, U.; Kempf, S.; Srama, R. +3 more
Saturn's E ring is remarkable not only for its huge size. Based on optical measurements the ring was surprisingly found to mainly consist of ice particles of uniform size (radii between 0.3 and 2 microns) [Nicholson et al., 1996. Observations of Saturn's ring-plane crossing in August and November. Science 272, 509-516], though the source of the ri…
Hydrogen cyanide polymers, comets and the origin of life
Matthews, Clifford N.; Minard, Robert D.
Hydrogen cyanide polymers - heterogeneous solids ranging in colour from yellow to orange to brown to black - could be major components of the dark matter observed on many bodies of the outer solar system including asteroids, moons, planets and, especially, comets. The presence on cometary nuclei of frozen volatiles such as methane, ammonia and wat…