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Non-Local Thermodynamic Equilibrium Model of NGC 6543's Central Star and Its Relation to the Surrounding Planetary Nebula
Hillier, D. J.; Richer, M. G.; Peimbert, M. +3 more
We analyze the chemical composition of the central star of the planetary nebula NGC 6543 based on a detailed NLTE model of its stellar wind. The logarithmic abundances by number are H = 12.00, He = 11.00, C = 9.03, N = 8.36, O = 9.02, Si = 8.19, P = 5.53, S = 7.57, and Fe = 7.24. Compared with the solar abundances, most of the elements have solar …
The Chandra Small Magellanic Cloud Wing Survey - the search for X-ray binaries
Coe, M. J.; McBride, V. A.; McGowan, K. E. +6 more
We have detected 523 sources in a survey of the Small Magellanic Cloud (SMC) Wing with Chandra. By cross-correlating the X-ray data with optical and near-infrared catalogues, we have found 300 matches. Using a technique that combines X-ray colours and X-ray to optical flux ratios, we have been able to assign preliminary classifications to 265 of t…
Cyclic behavior of solar full-disk activity
Li, K. J.; Gao, P. X.; Li, Q. X. +1 more
In order to describe the cyclic behavior of solar full-disk activity (the surface magnetic fields, filaments, the green Fe XIV, 5303Å corona local maxima intensities, and torsional oscillations), we propose a new concept, a "full-disk activity cycle," which consists of two successive normal cycles: a high-latitude activity cycle following a low-la…
Seyfert's Sextet: a Slowly Dissolving Stephan's Quintet?
Yun, M. S.; Plana, H.; Iovino, A. +7 more
We present a multiwavelength study of the highly evolved compact galaxy group known as Seyfert's Sextet (HCG79: SS). We interpret SS as a 2-3 Gyr more evolved analog of Stephan's Quintet (HCG92: SQ). We postulate that SS formed by sequential acquisition of 4-5 primarily late-type field galaxies. Four of the five galaxies show an early-type morphol…
XMM-Newton Discovery of 217 s Pulsations in the Brightest Persistent Supersoft X-Ray Source in M31
Trudolyubov, Sergey P.; Priedhorsky, William C.
We report on the discovery of a periodic modulation in the bright supersoft X-ray source XMMU J004252.5+411540 detected in the 2000-2004 XMM-Newton observations of M31. The source exhibits X-ray pulsations with a period P ~ 217.7 s and a quasi-sinusoidal pulse shape and pulsed fraction ~7%-11%. We did not detect statistically significant changes i…
Intergalactic He II Absorption in the Spectra of Quasars at Redshifts 3.5 and 3.8, Observed with the HST ACS Prism
Anderson, Scott F.; Schneider, Donald P.; York, Donald G. +8 more
We present the UV spectra of two quasars obtained with the Hubble Space Telescope Advanced Camera for Surveys (HST ACS) prism (R ~ 100). One quasar, at redshift z = 3.5, shows an absorption edge consistent either with nearly fully ionized helium with an intergalactic He II Lyα optical depth at 304 Å of τ304 > 3.1 (90% confidence), or…
The Role of Transient Brightenings in Heating the Solar Corona
Warren, Harry P.; Ugarte-Urra, Ignacio; Brooks, David H.
Nanoflare reconnection events have been proposed as a mechanism for heating the corona. Parker's original suggestion was that frequent reconnection events occur in coronal loops due to the braiding of the magnetic field. Many observational studies, however, have focused on the properties of isolated transient brightenings unassociated with loops, …
Coupled rotational dynamics of Saturn's thermosphere and magnetosphere: a thermospheric modelling study
Smith, C. G. A.; Aylward, A. D.
We use a numerical model of Saturn's thermosphere to investigate the flow of angular momentum from the atmosphere to the magnetosphere. The thermosphere model is driven by Joule heating and ion drag calculated from a simple model of the magnetospheric plasma flows and a fixed model of the ionospheric conductivity. We describe an initial study in w…
Polar Plume Brightening During the 2006 March 29 Total Eclipse
Rušin, V.; Druckmüller, M.; Minarovjech, M. +8 more
We discuss a remarkable brightening in a polar plume, as inferred from unique coordinated observations of the white-light corona during the total eclipse of the Sun of 2006 March 29. The polar plume (also known as a polar ray, with distinctions that we discuss) was observed at the positional angle of 9° the velocity at which the brightening propag…
Spectroscopic Confirmation of the Fifth Image of SDSS J1004+4112 and Implications for the MBH--σ* Relation at z = 0.68
Smith, Graham P.; Oguri, Masamune; Sharon, Keren +5 more
We present the results of deep spectroscopy for the central region of the cluster lens SDSSJ 1004+4112 with the Subaru Telescope. A secure detection of an emission line of the faint blue stellar object (component E) near the center of the brightest cluster galaxy (G1) confirms that it is the central fifth image of the lensed quasar system. In addi…