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Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A 13 Year Study of Spectral Variability in NGC 5548
Filippenko, A. V.; Shapovalova, A. I.; Chavushyan, V. H. +38 more
We present the final installment of an intensive 13 year study of variations of the optical continuum and broad Hβ emission line in the Seyfert 1 galaxy NGC 5548. The database consists of 1530 optical continuum measurements and 1248 Hβ measurements. The Hβ variations follow the continuum variations closely, with a typical time delay of about 20 da…
Stellar and wind properties of LMC WC4 stars. A metallicity dependence for Wolf-Rayet mass-loss rates
Hillier, D. J.; Crowther, P. A.; Fullerton, A. W. +2 more
We use ultraviolet space-based (FUSE, HST) and optical/IR ground-based (2.3 m MSSSO, NTT) spectroscopy to determine the physical parameters of six WC4-type Wolf-Rayet stars in the Large Magellanic Cloud. Stellar parameters are revised significantly relative to Gräfener et al. (\cite{Grafener1998}) based on improved observations and more sophistica…
The Dark Matter Density Profile of the Lensing Cluster MS 2137-23: A Test of the Cold Dark Matter Paradigm
Treu, Tommaso; Ellis, Richard S.; Sand, David J.
We present new spectroscopic observations of the gravitational arcs and the brightest cluster galaxy (BCG) in the cluster MS 2137-23 (z=0.313) obtained with the Echelle Spectrograph and Imager on the Keck II telescope. We find that the tangential and radial arcs arise from sources at almost identical redshifts (z=1.501, 1.502). We combine the meas…
High-Resolution Observations of the Elliptical Galaxy NGC 4636 with the Reflection Grating Spectrometer on Board XMM-Newton
Behar, E.; Kahn, S. M.; Mushotzky, R. F. +6 more
We present the first high spectral resolution X-ray observation of the giant elliptical galaxy NGC 4636, obtained with the reflection grating spectrometer on board the XMM-Newton Observatory. The resulting spectrum contains a wealth of emission lines from various charge states of oxygen, neon, magnesium, and iron. Examination of the cross-dispersi…
The signature of supernova ejecta in the X-ray afterglow of the γ-ray burst 011211
Schartel, N.; Ehle, M.; Watson, D. +8 more
Now that γ-ray bursts (GRBs) have been determined to lie at cosmological distances, their isotropic burst energies are estimated to be as high as 1054erg (ref. 2), making them the most energetic phenomena in the Universe. The nature of the progenitors responsible for the bursts remains, however, elusive. The favoured models range from t…
The Counterrotating Core and the Black Hole Mass of IC 1459
Carollo, C. M.; Illingworth, G. D.; Franx, M. +5 more
The E3 giant elliptical galaxy IC 1459 is the prototypical galaxy with a fast counterrotating stellar core. We obtained one Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) long-slit spectrum along the major axis of this galaxy and Cerro Tololo Inter-American Observatory (CTIO) spectra along five position angles. The signal…
The Far-Ultraviolet Spectrum of TW Hydrae. I. Observations of H2 Fluorescence
Herczeg, Gregory J.; Valenti, Jeff A.; Johns-Krull, Christopher M. +2 more
We observed the classical T Tauri star TW Hya with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope (HST) using the E140M grating, from 1150 to 1700 Å, with the E230M grating, from 2200 to 2900 Å, and with the Far Ultraviolet Spectroscopic Explorer from 900 to 1180 Å. Emission in 146 Lyman-band H2 lines, repr…
The Kinematic Connection between absorbing Gas toward QSOs and Galaxies at Intermediate Redshift
Dickinson, Mark; Pettini, Max; Shapley, Alice E. +3 more
We present complementary data on five intermediate-redshift (0.44<=z<=0.66) Mg II-absorbing galaxies, combining high spatial resolution imaging from the Hubble Space Telescope, high-resolution quasi-stellar object (QSO) spectroscopy from the Keck High Resolution Echelle Spectrometer, and galaxy kinematics from intermediate-resolution spectro…
Determination of geometrical and kinematical properties of halo coronal mass ejections using the cone model
Plunkett, S. P.; Zhao, X. P.; Liu, W.
Many broadside coronal mass ejections (CMEs) propagate almost radially beyond the first couple of solar radii, and their angular widths remain nearly constant while propagating through the corona. Assuming that these characteristics hold true for halo CMEs that originate far from solar limbs, some useful geometric and kinematic properties of halo …
New distances to galaxies in the Centaurus A group
Sarajedini, A.; Dolphin, A. E.; Grebel, E. K. +7 more
We present Hubble Space Telescope/WFPC2 images of seventeen dwarf galaxies in the Centaurus A group. Their distances derived from the magnitudes of the tip of the red giant branch are 5.2 Mpc (KK112), 3.2 Mpc (ESO 321-014), 3.5 Mpc (KK179), 3.4 Mpc (NGC 5102), 4.6 Mpc (KK200), 3.7 Mpc (ESO 324-024), 4.7 Mpc (KK208), 4.6 Mpc (ESO 444-084), 4.4 Mpc …