Search Publications
The dust environment of comet 67P/Churyumov-Gerasimenko
Rauer, H.; Fulle, M.; Barbieri, C. +4 more
The new target of the ESA Rosetta Mission is comet 67P/Churyumov-Gerasimenko, which passed its last perihelion on 18 August 2002 and was well observed from fall 2002 to spring 2003. Its most prominent feature was a thin dust tail, which is best fitted by the Neck-Line model. Fits of the whole tail provide the dust environment of 67P during a year …
Chandra Observations of the Three Most Metal Deficient Blue Compact Dwarf Galaxies Known in the Local Universe, SBS 0335-052, SBS 0335-052W, and I Zw 18
Bauer, Franz E.; Thuan, Trinh X.; Izotov, Yuri I. +1 more
We present an X-ray study of the three most metal deficient blue compact dwarf (BCD) galaxies known in the local universe, based on deep Chandra observations of SBS 0335-052 (0.025 Zsolar), SBS 0335-052W (0.02 Zsolar), and I Zw 18 (0.02 Zsolar). All three are detected, with more than 90% of their X-ray emission ari…
On the light echo in V838 Mon
Tylenda, R.
We present a theoretical outline of the light echo phenomenon and results of simple numerical simulations and we study the available images of the light echo in V838 Mon obtained with HST. An investigation of the observed expansion of the light echo leads us to conclude that the distance to V838 Mon is ⪆5 kpc. From an analysis of the inner bright …
The Iron Unresolved Transition Array in Active Galactic Nuclei
Netzer, Hagai
The unresolved transition array (UTA) of iron M-shell ions is a prominent absorption feature in the X-ray spectrum of many active galactic nuclei (AGNs). Modeling photoionized plasmas in an attempt to match the observed silicon and oxygen lines fails to predict the level of ionization of iron as inferred by this feature. It is suggested that the d…
Jupiter's Atmospheric Composition from the Cassini Thermal Infrared Spectroscopy Experiment
Smith, M. D.; Strobel, D. F.; Lellouch, E. +39 more
The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of a…
Hubble Space Telescope Observations of the Main Sequence of M4
Stetson, P. B.; Rich, R. M.; Shara, M. +8 more
We present new results from a photometric study of the main-sequence stars in M4 (NGC 6121=C1620-264), the closest globular cluster to the Sun. Multifield, multiepoch observations at approximately 1, 2, and 6 core radii were obtained with WFPC2 on the Hubble Space Telescope through either the F606W filter or the F555W (V) and F814W (I) filters. Th…
XMM-Newton observations of the INTEGRAL X-ray transient IGR J17544-2619
Parmar, A. N.; Kuulkers, E.; González-Riestra, R. +2 more
On September 17, 2003 INTEGRAL discovered a bright transient source 3° from the Galactic Center,
Asteroseismology of the β Cephei star ν Eridani - III. Extended frequency analysis and mode identification
Handler, G.; De Ridder, J.; Heiter, U. +7 more
Using the large photometric and spectroscopic data sets of the ν Eridani multisite campaign given in our two recent papers (Aerts et al. and Handler et al.), we present an extended frequency analysis and a photometric mode identification. For the extended frequency analysis, we used an improved radial velocity time series, the second-moment time s…
UV-photoprocessing of interstellar ice analogs: Detection of hexamethylenetetramine-based species
Schutte, W. A.; Greenberg, J. M.; Muñoz Caro, G. M. +2 more
The physical conditions governing the dense cloud environment are reproduced in a high vacuum experimental setup at low temperature T ≈ 12 K. The accretion and photoprocessing of ices on grain surfaces is simulated by depositing an ice layer on a cold finger, while it is irradiated by ultraviolet (UV) photons. After irradiation the sample is slowl…
Revisiting the Origin of Impulsive Electron Events: Coronal Magnetic Restructuring
Maia, Dalmiro Jorge Filipe; Pick, Monique
We revisit the impulsive beamlike particle events detected in situ from 1997 to 2000 by the Electron, Proton, and Alpha Monitor (EPAM) experiment on the Advanced Composition Explorer spacecraft. We study in detail a subset of events for which there are radio coronal observations from the Nançay Radioheliograph. EPAM measures electrons in the energ…