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Redshift-distance relations from type Ia supernova observations. New constraints on grey dust models
Cepa, J.; Robaina, A. R.
Extinction due to intergalactic grey dust has been proposed as an alternative to accelerated expansion to account for the dimming of SnIa fluxes beyond z ≃ 0.5. The "replenishing" grey dust model, although fitting the observational data, does not seem to be based on physical assumptions. For this reason, in this paper we propose a new grey dust mo…
Planetary science: Inside Enceladus
Spencer, John; Grinspoon, David
Chemical analysis of a plume emanating from near the south pole of Enceladus indicates that the interior of this saturnian moon is hot. Could it have been hot enough for complex organic molecules to be made?
The optical emission line spectrum of Mark 110
Kollatschny, W.; Véron-Cetty, M. -P.; Véron, P. +1 more
Aims:We analyse in detail the rich emission line spectrum of Mark 110 to determine the physical conditions in the nucleus of this object, a peculiar NLS1 without any detectable Fe II emission associated with the broad line region and with a λ5007/Hβ line ratio unusually large for a NLS1.
Methods: We use 24 spectra obtained with the Marcario Lo…
Effects of Foreshortening on Shallow Sub-surface Flows Observed with Local Helioseismology
Beckers, Jacques M.
From the results given in a recent paper by Zaatri et al. (2006, Solar Phys.236, 227) it is clear that foreshortening effects play a major role in estimating the magnitude and direction of meridional and other flows in the shallow solar sub-surface layers using local helioseismology. Using a different algorithm to account for these effects I arriv…
Sequential chromospheric brightenings: The case for chromospheric evaporation
Pevtsov, Alexei A.; Balasubramaniam, K. S.; Hock, Rachel A.
Sequential chromospheric brightenings (SCBs [Balasubramaniam, K.S., Pevtsov, A.A., Neidig, D.F., Cliver, E.W., Thompson, B.J., Young, C.A., Martin, S.F., & Kiplinger, A., 630, 1160, 2005.]) are observed in conjunction with some strong solar flares, prominence eruptions, and coronal mass ejections (CMEs). SCBs are seen as wave-like trains of in…
Thermal forces on planetary ring particles: application to the main system of Saturn
Vokrouhlický, D.; Nesvorný, D.; Dones, L. +1 more
Context: The motion of small particles in planetary rings is affected in the long-term by radiation forces. While the Poynting-Robertson effect has been extensively discussed and applied to the dynamics of micron-sized ring particles, studies of thermal self-acceleration of particles are only in their infancy.
Aims: We extend the pioneering wo…
Hubble Space Telescope Measurements of Vacuum Ultraviolet Lines of Interstellar CH
Federman, S. R.; Sheffer, Y.
Three interstellar absorption lines near 1370 Å seen toward ζ Oph have been assigned by Watson to Rydberg transitions in the G-X (or 3d-X) band of CH. Our survey of a dozen diffuse interstellar lines of sight shows that the three absorption lines are consistent with the known column densities of CH, by deriving the following oscillator strengths: …
Solar corona-induced fluctuations on spacecraft signal amplitude observed during solar superior conjunctions of the Cassini spacecraft
Morabito, David D.
During the superior solar conjunctions of interplanetary spacecraft, the emitted radio signals undergo increased amplitude scintillation, phase scintillation, and spectral broadening due to the intervening charged particles of the solar corona. The magnitude of these parameters generally increases as the angle between the spacecraft and the center…
Unveiling soft gamma-ray repeaters with INTEGRAL
Mereghetti, Sandro; Hurley, Kevin; Götz, Diego
Thanks to INTEGRAL's long exposures of the Galactic Plane, the two brightest Soft Gamma-Ray Repeaters, SGR 1806-20 and SGR 1900+14, have been monitored and studied in detail for the first time at hard-X/soft gamma rays. This has produced a wealth of new scientific results, which we will review here. Since SGR 1806-20 was particularly active during…
The distant galaxy cluster CL0016+16: X-ray analysis up to R{200}
Teyssier, R.; Solovyeva, L.; Anokhin, S. +2 more
Aims:CL0016+16 seems to be a good candidate for studying the mass distribution of galaxy clusters up to their Virial radius, since it is a bright massive cluster, previously considered as dynamically relaxed.
Methods: Using XMM-Newton observations of CL0016+16, we performed a careful X-ray background analysis and detected its X-ray emission co…