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121.
Q. D. Wang F. J. Lu E. V. Gotthelf 《Monthly notices of the Royal Astronomical Society》2006,367(3):937-944
We report the discovery of a prominent non-thermal X-ray feature located near the Galactic centre that we identify as an energetic pulsar wind nebula. This feature, G359.95-0.04, lies 1-lyr north of Sgr A* (in projection), is comet like in shape, and has a power-law spectrum that steepens with increasing distance from the putative pulsar. The distinct spectral and spatial X-ray characteristics of the feature are similar to those belonging to the rare class of ram-pressure confined pulsar wind nebulae. The luminosity of the nebula at the distance of Sgr A*, consistent with the inferred X-ray absorptions, is Lx ∼ 1 × 1034 erg s−1 in the 2–10 keV energy band. The cometary tail extends back to a region centred at the massive stellar complex IRS 13 and surrounded by an enhanced diffuse X-ray emission, which may represent an associated supernova remnant. Furthermore, the inverse Compton scattering of the strong ambient radiation by the nebula consistently explains the observed TeV emission from the Galactic centre. We also briefly discuss plausible connections of G359.95-0.04 to other high-energy sources in the region, such as the young stellar complexes IRS 13 and SNR Sgr A East. 相似文献
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D. Kilkenny C. Koen C. S. Jeffery N. C. Hill D. O'Donoghue 《Monthly notices of the Royal Astronomical Society》1999,310(4):1119-1127
We present extensive photometry and spectroscopy of the extremely hydrogen-deficient star, LSS 3184, recently discovered to be a rapid variable (period ∼0.1066 d) strikingly similar to V652 Her. Over 95 h of photometry confirms the reported variability, which is of rather low amplitude (Δ V ∼0.03 mag), defines the light curve with greater precision and establishes a much more accurate ephemeris (period ∼0.106 578 4 d) to form a basis for detecting period change. Attention is drawn to the usefulness of a period-finding technique that fits harmonic components to the photometric observations. Spectroscopy shows a peak-to-peak variation in radial velocity of about 30 km s−1 , which, when combined with the photometric observations, confirms the pulsational nature of the variability and strongly indicates that the pulsations are radial in nature. 相似文献
125.
David Kilkenny 《Astrophysics and Space Science》1995,230(1-2):53-61
A brief review is given of some of the recent SAAO observational programmes concerning various types of Hydrogen-deficient stars with some attempt to relate this work to general research in the field. The review covers R Coronæ Borealis (RCB) stars, Hydrogen-deficient Carbon (HdC) stars, and Extreme Helium (EHe) stars in the Carbon-rich group and AM CVn stars and the (apparently) unique star V652 Her in the Carbon-normal group. 相似文献
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Frédéric Zagury 《Journal of Astrophysics and Astronomy》2005,26(4):377-394
This paper examines the variations, because of atmospheric extinction, of broad-band visible spectra, obtained from long-slit
spectroscopy, in the vicinity of some stars, nebulae, and one faint galaxy. 相似文献