Search Publications
Cluster observations of O+ escape in the magnetotail due to shock compression effects during the initial phase of the magnetic storm on 17 August 2001
Zong, Q. -G.; Reme, H.; Korth, A. +5 more
We study the O+ outflow into the magnetotail during the initial phase of the 17 August 2001 magnetic storm. Solar wind and magnetospheric data are used from instruments onboard ACE, WIND, and Cluster spacecraft. The interplanetary shock arrival at Earth caused a large compression of the magnetosphere. During this event, the Cluster spac…
A New Orbit Determination for Bright Sungrazing Comet of 1843
Sekanina, Zdenek; Chodas, Paul W.
Given the critical role of the bright sungrazer C/1843 D1, also called the Great March Comet of 1843, in hypotheses of the origin and evolution of the Kreutz system, a new orbital investigation of this comet was desirable. Closely inspecting Kreutz's classical work, we conclude that his result of 512 yr for the orbital period, which has been endle…
Optical properties of aerosols in Titan's atmosphere
Keller, H. U.; Rodin, A. V.; Skorov, Yu. V.
In the frame of fractal modeling of tholin aggregates we made a systematic analysis of their optical properties. Ballistic particle-cluster aggregation (BPCA) and diffusion-limited aggregation (DLA) of spherical primary particles (monomers) identical in material composition were considered. Aggregates composed of identical particles (monodisperse …
INTEGRAL and BeppoSAX Observations of the Transient Atoll Source 4U 1608-522: From Quiescent to Hard Spectral State
Ubertini, P.; Bazzano, A.; Tarana, A.
We report on the spectral evolution of 4U 1608-522 using observations performed as part of the long-term Galactic bulge monitoring program with INTEGRAL. The data set includes the 2005 April outburst. BeppoSAX archival data (two observations, from 1998 and 2000) are also analyzed and compared with the INTEGRAL data. Three different spectral states…
The X-ray variability and the near-IR to X-ray spectral energy distribution of four low luminosity Seyfert 1 galaxies
Papadakis, I. E.; Brinkmann, W.; Xilouris, E. M. +1 more
Context: We present the results from a study of the X-ray variability and the near-IR to X-ray spectral energy distribution of four low-luminosity, Seyfert 1 galaxies.
Aims: We compared their variability amplitude and broad band spectrum with those of more luminous AGN in order to investigate whether accretion in low-luminosity AGN operates as…
The Faint-End Slopes of Galaxy Luminosity Functions in the COSMOS Field
Mobasher, Bahram; Capak, Peter; Rich, R. Michael +5 more
We examine the faint-end slope of the rest-frame V-band luminosity function (LF), with respect to galaxy spectral type, of field galaxies with redshift z < 0.5, using a sample of 80,820 galaxies with photometric redshifts in the 2 deg2 Cosmic Evolution Survey (COSMOS) field. For all galaxy spectral types combined, the LF slope ranges…
Transients in oxygen outflow above the polar cap as observed by the Cluster spacecraft
Lundin, R.; Yamauchi, M.; Sauvaud, J. -A. +11 more
Oxygen ion outflow associated with the cusp and cleft give rise to persistent oxygen ion beams which can be observed over the polar cap. For high altitude spacecraft such as Cluster these beams are often observed for several hours on each occasion. This allows for a study of typical temporal structures on the time scale of minutes. We have used 3 …
Probing the slope of cluster mass profile with gravitational Einstein rings: application to Abell 1689
Jullo, E.; Fort, B.; Richard, J. +5 more
The strong lensing modelling of gravitational 'rings' formed around massive galaxies is sensitive to the amplitude of the external shear and convergence produced by nearby mass condensations. In current wide-field surveys, it is now possible to find out a large number of rings, typically 10 gravitational rings per square degree. We propose here, t…
Photoevaporation of Protoplanetary Disks
Rieke, George H.; Bally, John; Gáspár, András +4 more
We present HST NICMOS Paschen α (Paα) images and low- and high-resolution IRS spectra of photoevaporating disk-tail systems originally detected at 24 µm near O stars. We find no Paα emission in any of the systems. The resulting upper limits correspond to about (2-3) × 10-6 M⊙ of mass in hydrogen in the tails, suggesting…
The Mechanisms of Particle Kinetics and Dynamics Leading to Seismic Emission and Sunquakes
Zharkova, V. V.
In this paper the mechanisms responsible for observational features associated with sunquakes induced by different classes of solar flares are compared. The role of high-energy particle beams via Coulomb and Ohmic heating of the ambient plasma and nonthermal excitation and ionization is explored for different beam parameters at various atmospheric…