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Absolute Magnitudes of Be Stars Based on Hipparcos Parallaxes
Zhang, P.; Chen, P. S.; Liu, C. Q.
The absolute visual magnitudes of 457 Be stars are determined from Hipparcos parallaxes, subsequently the mean absolute visual magnitudes of Be stars for luminosity classes III, IV and V are obtained. The new Mv calibration is compared with existing calibrations. It is found that Be stars are generally brighter than B stars of the corresponding sp…
A systematic search of highly variable X-ray sources with the XMM-Newton serendipitous survey
Yuan, Weimin; Komossa, Stefanie; Osborne, Julian P. +1 more
We describe an ongoing programme to search for X-ray sources with long-term, large amplitude X-ray variability. The method is to compare the X-ray sources from the XMM-Newton Serendipitous Survey with those from the previous ROSAT pointed observations and the ROSAT All-sky Survey. The work is largely motivated by the recent discovery of a new type…
Two candidate homologous CMEs on 2002 May 22
Cheng, J. X.; Chen, P. F.; Fang, C.
Two coronal mass ejections (CMEs) occurred on 2002 May 22, originating from the same active region, AR 9948. Multi-wavelength data are collected in order to clarify the relationship between the CMEs, the associated flares and filament eruptions, and some other magnetic activities, which is of great importance to understand the mechanism of each ph…
Comment on ``Interplanetary shocks unconnected with earthbound coronal mass ejections'' by T. A. Howard and S. J. Tappin
Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji +1 more
Abstract Available from http://www.agu.org
XMM-Newton Observations of X-Ray Emission from Jupiter
Branduardi-Raymont, G.; Soria, R.; Ramsay, G. +6 more
XMM-Newton observations of Jupiter show prominent soft X-ray emission from the auroral spots and, albeit at a lower intensity, from the equatorial regions. While the spectra of the auroral X-rays can be modeled with a superposition of unresolved emission lines, including most prominently those of highly ionized oxygen, Jupiter's equatorial ‘disk’ …
Stellar population of the central regions of NGC 5128
Tikhonov, N. A.; Galazutdinova, O. A.; Hagen-Thorn, V. A. +1 more
We present the results of stellar photometry in eight fields of NGC 5128 (Cen A), a candidate polar-ring galaxy, obtained by reducing images from the Hubble Space Telescope archive. In all cases, the color-magnitude diagrams reached the red-giant region, and the distance to the galaxy was determined from the position of the tip of the red-giant br…
Strong magnetic asymmetries in weakly interacting spirals
Ehle, M.; Beck, R.; Chyży, K. T.
We investigate the influence of cluster environment on the structure and evolution of magnetic fields and the interstellar medium in the Virgo cluster spiral NGC 4254. Our sensitive interferometric (VLA) and single dish (Effelsberg) radio polarimetric observations reveal several magnetic spiral arms displaced from optical ones. However, the southe…
Variability of the Fe K line relativistic component in a sample of Seyfert 1 galaxies
Cappi, M.; Dadina, M.; De Marco, B. +1 more
We present the analysis of X-ray spectral variability made on a sample of 7 Seyfert 1 bright galaxies, using XMM-Newton data. From the ``XMM-Newton Science Archive'' we selected those bright Seyfert 1 showing one or more prominent flares in their 2-10 keV light curves. For each of them we extracted spectra in 3 different time intervals: before, du…
Millisecond Pulsar Population in the Galactic Center and High Energy Contributions
Wang, Wei
We propose that there possibly exists a population of millisecond pulsars in the Galactic center region. Millisecond pulsars (MSPs) could emit GeV gamma-rays through synchrotron-curvature radiation as predicted by outer gap models. In the same time, the compact wind nebulae around millisecond pulsars can emit X-rays though synchrotron radiation an…
XMM-Newton observations of low luminosity Be/X-ray candidates
Haberl, F.; Motch, C.; Janot-Pacheco, E. +2 more
A small number of early Be stars exhibit X-ray luminosities intermediate between those typical of early type stars and those radiated by Be/X-ray binaries in the quiescent state. We report on XMM-Newton observations of two such Be stars, HD 161103 and SAO 49725 which were originally discovered in a systematic cross-correlation between the ROSAT al…