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Polycyclic Aromatic Hydrocarbons and Crystalline Silicates in the Bipolar Post-Asymptotic Giant Branch Star IRAS 16279-4757
Waters, L. B. F. M.; Hony, S.; Zijlstra, A. A. +7 more
IRAS 16279-4757 belongs to a group of post-asymptotic giant branch (post-AGB) stars showing both polycyclic aromatic hydrocarbon (PAH) bands and crystalline silicates. We present mid-infrared images that resolve the object for the first time. The morphology is similar to that of the ``Red Rectangle'' (HD 44179), the prototype object with PAHs and …
Are Giant Planets Forming around HR 4796A?
Kamp, I.; Chen, C. H.
We have obtained Far Ultraviolet Spectroscopic Explorer and Hubble Space Telescope STIS spectra of HR 4796A, a nearby 8 Myr old main-sequence star that possesses a dusty circumstellar disk whose inclination has been constrained from high-resolution near-infrared observations to be ~17° from edge-on. We searched for circumstellar absorption in the …
The influence of density stratification and multiple nonlinearities on solar torsional oscillations
Covas, E.; Moss, D.; Tavakol, R.
Analyses of recent helioseismic data have produced ample evidence for substantial dynamical variation of the differential rotation within the solar convection zone. Given the inevitable difficulties in resolving the precise nature of variations in deeper layers, much effort has recently gone into determining theoretically the expected modes of beh…
Carina's defiant Finger: HST observations of a photoevaporating globule in NGC 3372*
Walborn, Nolan R.; Smith, Nathan; Barbá, Rodolfo H.
We present Hubble Space Telescope Wide Field Planetary Camera 2 images of a prominent externally ionized molecular globule in the Carina Nebula (NGC 3372), supplemented with ground-based infrared images and visual-wavelength spectra. This molecular globule has a shape resembling a human hand, with an extended finger that points toward its likely s…
Temperature map computation for X-ray clusters of galaxies
Bijaoui, A.; Bourdin, H.; Slezak, E. +2 more
Recent numerical simulations have shown that the variations of the gas temperature in clusters of galaxies are indicative of the dynamical state of these clusters. Maps of the temperature variation show complex structures with different shapes at different spatial scales, such as hot compression regions, filaments, cooling flows, or large-scale te…
Titan's surface and rotation: new results from Voyager 1 images
McEwen, Alfred; Lorenz, Ralph D.; Richardson, James
We present an analysis of images of Saturn's moon Titan, obtained by the Voyager 1 spacecraft on November 8-12, 1980. Orange filter (590-640 nm) images were photometrically corrected and a longitudinal average removed from them, leaving residual images with up to 5% contrast, and dominated by surface reflectivity. The resultant map shows the same …
Structure Properties of Supergranulation and Granulation
Kosovichev, A. G.; Pietropaolo, E.; Duvall, T. L., Jr. +3 more
We investigate spatial dislocation ordering of the solar structures associated with supergranulation and granulation scales. The supergranular and granular structures are automatically segmented from time-distance divergence maps and from broad-band images, respectively. The spatial dislocation ordering analysis is accomplished by applying the sta…
Origin of diffuse C II 158 micron and Si II 35 micron emission in the Carina nebula
Onaka, T.; Shibai, H.; Mizutani, M.
We present the results of mapping observations with ISO of [O I] 63 µm, 145 µm, [N II] 122 µm, [C II] 158 µm, [Si II] 35 µm, and H_2 9.66 µm line emissions for the Carina nebula, an active star-forming region in the Galactic plane. The observations were made for the central 40 arcmin × 20 arcmin area of the nebu…
WZ Sagittae: Hubble Space Telescope Spectroscopy of the Cooling of the White Dwarf after the 2001 Outburst
Szkody, Paula; Sion, Edward M.; Gänsicke, Boris T. +1 more
Following an outburst in 2001 July, the UV flux of WZ Sge has declined slowly toward preoutburst levels. Here we describe new 1150-1710 Å Hubble Space Telescope STIS spectra of WZ Sge obtained between 2002 April and 2003 March to follow the decline. A combined analysis of these and spectra obtained in the fall of 2001 show that if logg=8.5, then t…
An Unusual Discontinuity in the X-Ray Surface Brightness Profile of NGC 507: Evidence of an Abundance Gradient?
Churazov, E.; Vikhlinin, A.; Markevitch, M. +5 more
We present results from a 45 ks Chandra ACIS-I observation of the nearby (z=0.01646) NGC 507 group. The X-ray surface brightness profile of the outer region of the group is well described by an isothermal β-profile consistent with earlier ROSAT observations. We find a sharp edge or discontinuity in the radial surface brightness profile 55 kpc east…