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A photometric study of the ages and metallicities of early-type galaxies in A 2218
Smith, G. P.; Smail, Ian; Fruchter, A. S. +4 more
We present deep optical and near-infrared imaging of the rich cluster A2218 at z=0.17. Our optical imaging comes from new multicolour Hubble Space Telescope WFPC2 observations in the F450W (B450), F606W (V606) and F814W (I814) passbands. These observations are complemented by deep near-infrared, Ks-band …
Evidence of a Supermassive Black Hole in the Galaxy NGC 1023 from the Nuclear Stellar Dynamics
Nelson, C.; Bender, R.; Green, R. F. +13 more
We analyze the nuclear stellar dynamics of the SB0 galaxy NGC 1023, utilizing observational data both from the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope and from the ground. The stellar kinematics measured from these long-slit spectra show rapid rotation (V~70 km s-1 at a distance of 0.1"=4.9 pc from the nuc…
LBQS 0103-2753: A 0.3" Binary Quasar
Burbidge, E. M.; Junkkarinen, V.; Shields, G. A. +4 more
Imaging and spectroscopy with the Hubble Space Telescope show that LBQS 0103-2753 (V=17.8, z=0.848) is a binary quasar with a separation of 0.3", or 2.3 kpc. This is by far the smallest separation binary quasar reported to date. The two components have very different spectra, including the presence of strong broad absorption lines (BALs) in compon…
Ionization state and magnetic topology of coronal mass ejections
Woch, J.; Schwenn, R.; Balogh, A. +5 more
Charge state distributions of heavy solar wind ions measured in interplanetary space can be used to probe the physical conditions in the solar corona. This paper presents a study of the charge state distributions and the magnetic topology of 56 coronal mass ejections (CMEs) observed in interplanetary space by the Ulysses spacecraft. The analysis o…
High-Velocity Cloud Complex C: Galactic Fuel or Galactic Waste?
Shull, J. Michael; Stocke, John T.; Gibson, Brad K. +3 more
We present HST Goddard High Resolution Spectrograph and Space Telescope Imaging Spectrograph observations of five quasi stellar objects that probe the prominent high-velocity cloud (HVC) Complex C, covering ~10% of the northern sky. Based upon a single sight-line measurement (Mrk 290), a metallicity [S/H]=-1.05+/-0.12 has been associated with Comp…
Tailored Analyses of the WN 8 Stars WR 40 and WR 16
Hillier, D. J.; Herald, J. E.; Schulte-Ladbeck, R. E.
We present the results of tailored spectral analyses of two WN 8 Wolf-Rayet stars: WR 40 (HD 96548) and WR 16 (HD 86161). These analyses were carried out utilizing line-blanketed non-LTE model atmospheres with provisions for a clumped wind. For the first time in WN analyses, stellar parameters are derived by attempting to match the entire observed…
Why Are Solar Filaments More Extended in Extreme-Ultraviolet Lines than in Hα?
Heinzel, P.; Schmieder, B.; Tziotziou, K.
A long solar filament was observed simultaneously in the Hα line by THEMIS/MSDP and in selected EUV lines by the Coronal Diagnostic Spectrometer on SOHO. Co-alignment of optical and EUV images reveals that the dark EUV filament is much more extended than the Hα filament. Assuming that the EUV filament represents Lyman continuum absorption of the b…
A mosaic of the Coma cluster of galaxies with XMM-Newton
Aghanim, N.; Arnaud, M.; Vestrand, W. T. +7 more
The
Imaging an Emerging Active Region with Helioseismic Tomography
Christensen-Dalsgaard, Jørgen; Duvall, Thomas L., Jr.; Jensen, Jesper Munk +1 more
The wave-speed structure beneath an emerging active region is derived from helioseismic time-distance data using inversion techniques developed in geophysics. We use Fresnel zone-based sensitivity kernels along with a Fourier domain-based regularized least-squares inversion technique. The results show that wave-speed anomalies extend down to 20 Mm…
The Discovery of Cepheids and a New Distance to NGC 2841 Using the Hubble Space Telescope
Garnavich, P. M.; Richmond, M. W.; Stetson, P. B. +5 more
We report on the discovery of Cepheids in the spiral galaxy NGC 2841, based on observations made with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. NGC 2841 was observed over 12 epochs using the F555W filter and over five epochs using the F814W filter. Photometry was performed using the DAOPHOT/ALLFRAME package. We discove…