Search Publications
XMM-Newton observations of bright ROSAT selected active galactic nuclei with low intrinsic absorption
Pietsch, W.; Boller, Th.; Brinkmann, W. +4 more
We present a sample of 21 ROSAT bright active galactic nuclei (AGNs), representing a range of spectral classes, and selected for follow-up snapshot observations with XMM-Newton. The typical exposure was between 5 and 10ks. The objects were primarily selected on the bases of X-ray brightness and not on hardness ratio; thus the sample cannot be stri…
New γ Cassiopeiae-like objects: X-ray and optical observations of SAO 49725 and HD 161103
Haberl, F.; Motch, C.; Janot-Pacheco, E. +2 more
A growing number of early Be stars exhibit X-ray luminosities that are intermediate between those typical of early type stars and those emitted by most Be/X-ray binaries in quiescence. We report on XMM-Newton observations of two such Be stars,
Milliarcsecond-Scale Spectral Properties and Jet Motions in M 87
Dodson, Richard; Edwards, Philip G.; Hirabayashi, Hisashi
We have combined high resolution VLBI Space Observatory Programme (VSOP) data at 1.6 and 4.8GHz with Very Long Baseline Array (VLBA) data at higher frequencies and with similar resolutions to study the spectral properties of the core of M 87 with milliarcsec resolution. The VSOP data allows a more accurate measurement of the turnover frequency, an…
Properties and geoeffectiveness of halo coronal mass ejections
Gopalswamy, N.; Michalek, G.; Yashiro, S. +1 more
Halo coronal mass ejections (HCMEs) originating from regions close to the center of the Sun are likely to be geoeffective. Assuming that the shape of HCMEs is a cone and that the HCMEs propagate with constant angular widths and velocities, at least in their early phase, we have developed a technique which allowed us to obtain the space speed, widt…
Diagnostics for specific PAHs in the far-IR: searching neutral naphthalene and anthracene in the Red Rectangle
Joblin, C.; Toublanc, D.; Mulas, G. +1 more
Context: .In the framework of the interstellar polycyclic aromatic hydrocarbons (PAHs) hypothesis, far-IR skeletal bands are expected to be the fingerprints of single species in this class.
Aims: .We address the question of detectability of low energy PAH vibrational bands, with respect to spectral contrast and intensity ratio with "classical"…
Luminous Compact Blue Galaxies up to z~1 in the Hubble Space Telescope Ultra Deep Field. I. Small Galaxies or Blue Centers of Massive Disks?
Koo, D. C.; Melbourne, J.; Willmer, C. N. A. +4 more
We analyze 26 luminous compact blue galaxies (LCBGs) in the Hubble Space Telescope ACS Ultra Deep Field (UDF) at z~0.2-1.3, to determine whether these truly are small galaxies or, rather, bright central starbursts within existing or forming large disk galaxies. Surface brightness profiles from UDF images reach fainter than rest-frame 26.5 B mag ar…
Comet nuclei: Morphology and implied processes of surface modification
Keller, H. U.; Basilevsky, A. T.
Surface morphology and related issues for nuclei of three comets: Halley, Borrelly and Wild 2, are considered in the paper. Joint consideration of publications and results of our analysis of the comets' images led to conclusions, partly new, partly repeating conclusions published by other researchers. It was found that typical for all three nuclei…
Formation and evolution of late-type dwarf galaxies - I. NGC1705 and NGC1569
Matteucci, Francesca; Tosi, Monica; Romano, Donatella
We present one-zone chemical evolution models for two dwarf starburst galaxies, NGC1705 and NGC1569. Though especially designed for the inner ~1 kpc region, where numerous HII regions and most of the stars are observed, the models also account for the presence of extended gaseous and dark matter haloes, and properly compute the binding energy of t…
Sources of the Solar Wind at Ulysses during 1990-2006
Sheeley, N. R., Jr.; Wang, Y. -M.
The Ulysses spacecraft is now well into its third polar orbit around the Sun. Using stackplot displays, we summarize the wind speeds and interplanetary sector polarities recorded by Ulysses since its launch in 1990 and relate the observed patterns to the global evolution of open magnetic regions (coronal holes) over the solar cycle. We verify that…
Characteristics of dust particles detected near Saturn's ring plane with the Cassini Radio and Plasma Wave instrument
Gurnett, D. A.; Persoon, A. M.; Kurth, W. S. +2 more
During the inbound and outbound passes of the Cassini spacecraft through Saturn's ring plane on July 1, 2004, the Radio and Plasma Wave Science (RPWS) instrument detected many small particles striking the spacecraft. When a small particle strikes the spacecraft at a high velocity, it is instantly vaporized and produces a small cloud of plasma that…