Search Publications
On Relativistic Disk Spectroscopy in Compact Objects with X-ray CCD Cameras
Haberl, F.; Fabian, A. C.; Miller, J. M. +11 more
X-ray charge-coupled devices (CCDs) are the workhorse detectors of modern X-ray astronomy. Typically covering the 0.3-10.0 keV energy range, CCDs are able to detect photoelectric absorption edges and K shell lines from most abundant metals. New CCDs also offer resolutions of 30-50 (E/ΔE), which is sufficient to detect lines in hot plasmas and to r…
X-ray Emission from Nitrogen-Type Wolf-Rayet Stars
Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel +2 more
We summarize new X-ray detections of four nitrogen-type Wolf-Rayet (WR) stars obtained in a limited survey aimed at establishing the X-ray properties of WN stars across their full range of spectral subtypes. None of the detected stars is so far known to be a close binary. We report Chandra detections of WR 2 (WN2), WR 18 (WN4), and WR 134 (WN6), a…
Electron acceleration signatures in the magnetotail associated with substorms
Fazakerley, A. N.; Daly, P. W.; Vaivads, A. +13 more
We present Cluster multisatellite observations of accelerated electrons in the near-Earth magnetotail associated with substorms. We found that the hardest electron energy spectra appear in the earliest stage of substorm expansion in the near-Earth tail region and that they gradually become softer during the events. Enhancement of the high-energy e…
An Efficient Approximation of the Coronal Heating Rate for use in Global Sun-Heliosphere Simulations
Cranmer, Steven R.
The origins of the hot solar corona and the supersonically expanding solar wind are still the subject of debate. A key obstacle in the way of producing realistic simulations of the Sun-heliosphere system is the lack of a physically motivated way of specifying the coronal heating rate. Recent one-dimensional models have been found to reproduce many…
The helium spread in the globular cluster 47 Tuc
D'Antona, F.; Ventura, P.; Piotto, G. +2 more
Spectroscopy has shown the presence of CN band dichotomy and Na-O anticorrelations for 50-70 per cent of the investigated samples in the cluster 47 Tuc, otherwise considered a `normal' prototype of high-metallicity clusters from its photometric analysis. These anomalies are also found in main-sequence stars, suggesting that a consistent second gen…
``TNOs are Cool'': A survey of the trans-Neptunian region . III. Thermophysical properties of 90482 Orcus and 136472 Makemake
Fornasier, S.; Groussin, O.; Thomas, N. +32 more
Context. The goal of the Herschel open time programme “TNOs are Cool!” is to derive the physical and thermal properties for a large sample of Centaurs, and trans-Neptunian objects (TNOs), including resonant, classical, detached and scattered disk objects.
Aims: Based on observations of two targets we tried (i) to optimise the SPIRE observing …
The dust trail of Comet 67P/Churyumov-Gerasimenko between 2004 and 2006
Reach, William T.; Agarwal, Jessica; Grün, Eberhard +3 more
We report on observations of the dust trail of Comet 67P/Churyumov-Gerasimenko (CG) in visible light with the Wide Field Imager at the ESO/MPG 2.2 m telescope at 4.7 AU before aphelion, and at 24µm with the MIPS instrument on board the Spitzer Space Telescope at 5.7 AU both before and after aphelion. The comet did not appear to be active dur…
Link between EMIC waves in a plasmaspheric plume and a detached sub-auroral proton arc with observations of Cluster and IMAGE satellites
Lucek, E.; Frey, H. U.; Décréau, P. M. E. +7 more
In this paper, we report observations from a Cluster satellite showing that ULF wave occurred in the outer boundary of a plasmaspheric plume on September 4, 2005. The band of observed ULF waves is between the He+ ion gyrofrequency and O+ ion gyrofrequency at the equatorial plane, implying that those ULF waves can be identifie…
Spectroscopic observations of ices around embedded young stellar objects in the Large Magellanic Cloud with AKARI
Onaka, T.; Sakon, I.; Kaneda, H. +4 more
Aims: The aim of this study is to understand the chemical conditions of ices around embedded young stellar objects (YSOs) in the metal-poor Large Magellanic Cloud (LMC).
Methods: We performed near-infrared (2.5-5 µm) spectroscopic observations toward 12 massive embedded YSOs and their candidates in the LMC using the infrared camera…
Is there a highly magnetized neutron star in GX 301-2?
Klochkov, D.; Santangelo, A.; Ferrigno, C. +4 more
We present the results of an in-depth study of the long-period X-ray pulsar GX 301-2. Using archival data of INTEGRAL, RXTE ASM, and CGRO BATSE, we study the spectral and timing properties of the source. Comparison of our timing results with previously published work reveals a secular decay of the orbital period at a rate of ≃ - 3.25 × 10-5