We present results from two Chandra X-ray Observatory observations of the X-ray point source population in the nearby radio galaxy Centaurus A (NGC 5128). Using a wavelet decomposition detection algorithm, we detect 246 individual point sources above a limiting luminosity of D2 ] 1036 ergs s~1, 82 of which are detected in both data sets where the Ðelds of view overlap. Thirty-eight sources were detected in only one observation but were within the Ðeld of view of both pointings, implying considerable variability. We identify eight foreground stars in our observations. We also identify nine of the sources with known globular clusters in Centaurus A. All previously observed ROSAT sources within our Ðeld of view are detected. The number of luminous ergs s~1) X-ray binaries per unit (L x [ 1037 optical luminosity in Cen A is roughly consistent with that observed for the M31 bulge. There are approximately 50% more X-ray binaries per unit optical luminosity in Centaurus A than in the whole of M31, however. We Ðnd considerably fewer luminous X-ray binaries per unit optical luminosity in Cen A than in two other elliptical galaxies, M84 and NGC 4697, recently observed by Chandra. This result directly conÐrms the variance in the X-ray binary population with host galaxy optical luminosity previously inferred from spectral analysis of ROSAT and ASCA observations of elliptical galaxies.
We report precise Doppler measurements of two stars, obtained at Lick Observatory as part of our search for planets orbiting intermediate-mass subgiants. Periodic variations in the radial velocities of both stars reveal the presence of substellar orbital companions. These two stars are notably massive with stellar masses of 1.80 and 1.64 M , respectively, indicating that they are former A-type dwarfs that have evolved off of the main sequence and are now K-type subgiants. The planet orbiting CrB has a minimum mass M P sin i ¼ 1:8 M Jup , eccentricity e ¼ 0:146 and a 1208 day period, corresponding to a semimajor axis a ¼ 2:7 AU. The planet around HD 167042 has a minimum mass M P sin i ¼ 1:7 M Jup and a 412.6 day orbit, corresponding to a semimajor axis a ¼ 1:3 AU. The eccentricity of HD 167042b is consistent with circular (e ¼ 0:027 AE 0:04), adding to the rare class of known exoplanets in longperiod, circular orbits similar to the solar system gas giants. Like all of the planets previously discovered around evolved A stars, CrBb and HD 167042b orbit beyond 0.8 AU.
We present SPEAR/FIMS far-ultraviolet observations near the North Ecliptic Pole. This area, at b ∼ 30 • and with intermediate Hi column, seems to be a fairly typical line of sight that is representative of general processes in the diffuse ISM. We detect a surprising number of emission lines of many elements at various ionization states representing gas phases from the warm neutral medium (WNM) to the hot ionized medium (HIM). We also detect fluorescence bands of H 2 , which may be due to the ubiquitous diffuse H 2 previously observed in absorption.
Diffuse far-UV emission arising from the edge of the Orion-Eridanus superbubble was observed with the SPEAR imaging spectrometer, revealing numerous emission lines arising from both atomic species and H 2 . Spatial variations in line intensities of Civ, Siii, and Ovi, in comparison with soft X-ray, Hα and dust data, indicate that these ions are associated with processes at the interface between hot gas inside the bubble and the cooler ambient medium. Thus our observations probe physical conditions of an evolved thermal interface in the ISM.
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