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WIYN open cluster study. XXVI. Improved kinematic membership and spectroscopy of IC 2391
Kozhurina-Platais, V.; Altmann, M.; Platais, I. +5 more
Context: Young open clusters provide important clues to the interface between the main sequence and pre-main-sequence phases of stellar evolution. The young and nearby open cluster IC 2391 is well-suited to studies of these two evolutionary phases.
Aims: We establish a bona fide set of cluster members and then analyze this set in terms of bina…
Static and Dynamic Modeling of a Solar Active Region
Winebarger, Amy R.; Warren, Harry P.
Recent hydrostatic simulations of solar active regions have shown that it is possible to reproduce both the total intensity and the general morphology of the high-temperature emission observed at soft X-ray wavelengths using static heating models. These static models, however, cannot account for the lower temperature emission. In addition, there i…
XMM-Newton and INTEGRAL spectroscopy of the microquasar GRO J1655-40 during its 2005 outburst
Díaz Trigo, M.; Parmar, A. N.; Kuulkers, E. +2 more
We report on two simultaneous XMM-Newton and INTEGRAL observations of the microquasar GRO J1655-40during the 2005 outburst when the source was in its high-soft state. The 0.3-200 keV spectra are complex with an overall continuum which may be modeled using an absorbed blackbody together with a weak, steep, power-law component. In addition, there is…
X-Ray Timing of PSR J1852+0040 in Kesteven 79: Evidence of Neutron Stars Weakly Magnetized at Birth
Camilo, F.; Gotthelf, E. V.; Halpern, J. P. +1 more
The 105 ms X-ray pulsar J1852+0040 is the central compact object (CCO) in supernova remnant Kes 79. We report a sensitive upper limit on its radio flux density of 12 µJy at 2 GHz using the NRAO Green Bank Telescope. Timing using the Newton X-Ray Multi-Mirror Mission (XMM-Newton) and the Chandra X-Ray Observatory over a 2.4 yr span reveals no…
The impact of accretion disc winds on the X-ray spectrum of AGN - I. XSCORT
Schurch, N. J.; Done, C.
The accretion disc in active galactic nucleus (AGN) is expected to produce strong outflows, in particular an ultraviolet (UV)-line-driven wind. Several observed spectral features, including the soft X-ray excess, have been associated with the accretion disc wind. However, current spectral models of the X-ray spectrum of AGN observed through an acc…
The Black Hole Mass and Extreme Orbital Structure in NGC 1399
Filippenko, Alexei V.; Ho, Luis C.; Gebhardt, Karl +12 more
The largest galaxies, and in particular central galaxies in clusters, offer unique insight into understanding the mechanism for the growth of nuclear black holes. We present Hubble Space Telescope kinematics for NGC 1399, the central galaxy in Fornax. We find the best-fit model contains a black hole of (5.1+/-0.7)×108 Msolar …
ROMAP: Rosetta Magnetometer and Plasma Monitor
Russell, C. T.; Kührt, E.; Richter, I. +18 more
The scientific objectives, design and capabilities of the Rosetta Lander's ROMAP instrument are presented. ROMAP's main scientific goals are longterm magnetic field and plasma measurements of the surface of Comet 67P/Churyumov-Gerasimenko in order to study cometary activity as a function of heliocentric distance, and measurements during the Lander…
BLOX: the Bonn lensing, optical, and X-ray selected galaxy clusters. I. Cluster catalog construction
Schneider, P.; Maturi, M.; Schwope, A. +4 more
The mass function of galaxy clusters is an important cosmological probe. Differences in the selection method could potentially lead to biases when determining the mass function. From the optical and X-ray data of the XMM-Newton Follow-Up Survey, we obtained a sample of galaxy cluster candidates using weak gravitational lensing, the optical Postm…
An unexpected cooling effect in Saturn's upper atmosphere
Millward, G. H.; Miller, S.; Smith, C. G. A. +2 more
The upper atmospheres of the four Solar System giant planets exhibit high temperatures that cannot be explained by the absorption of sunlight. In the case of Saturn the temperatures predicted by models of solar heating are ~200K, compared to temperatures of ~400K observed independently in the polar regions and at 30° latitude. This unexplained `en…
Detailed Far-Ultraviolet to Optical Analysis of Four [WR] Stars
Pereira, C. B.; Hillier, D. J.; Marcolino, W. L. F. +1 more
We present far-UV to optical analyses of four hydrogen-deficient central stars of planetary nebulae: BD +30 3639, NGC 40, NGC 5315, and NGC 6905. Using the radiative transfer code CMFGEN, we determined new physical parameters and chemical abundances for these stars. The results were analyzed in the context of the [WR]-->PG 1159 evolution via th…