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Supermassive Black Holes in Bulges
Filippenko, Alexei V.; Ho, Luis C.; Shields, Joseph C. +5 more
We present spatially extended gas kinematics at parsec-scale resolution for the nuclear regions of four nearby disk galaxies and model them as rotation of a gas disk in the joint potential of the stellar bulge and a putative central black hole. The targets were selected from a larger set of long-slit spectra obtained with the Hubble Space Telescop…
New Insights on the Draco Dwarf Spheroidal Galaxy from the Sloan Digital Sky Survey: A Larger Radius and No Tidal Tails
Grebel, Eva K.; York, Donald G.; Holtzman, Jon +20 more
We have investigated the spatial extent and structure of the Draco dwarf spheroidal galaxy by using deep wide-field multicolor CCD photometry from the Sloan Digital Sky Survey (SDSS). Our study covers an area of 27 deg2 around the center of the Draco dwarf and reaches 2 mag below the level of Draco's horizontal branch. The SDSS photomet…
Star Formation in the Field and Clusters of NGC 5253
Heckman, Timothy M.; Calzetti, Daniela; Leitherer, Claus +1 more
We investigate the star formation history of both the bright star clusters and the diffuse ``field star'' population in the dwarf starburst galaxy NGC 5253 using long-slit ultraviolet spectroscopy obtained with the Space Telescope Imaging Spectrograph. The slit covers a physical area of 370 pc×1.6 pc and includes eight apparent clusters and severa…
First results from the RAPID imaging energetic particle spectrometer on board Cluster
Livi, S.; Grande, M.; Carter, M. +28 more
The advanced energetic particle spectrometer RAPID on board Cluster can provide a complete description of the relevant particle parameters velocity, V , and atomic mass, A, over an energy range from 30 keV up to 1.5 MeV. We present the first measurements taken by RAPID during the commissioning and the early operating phases. The orbit on 14 Januar…
Structure of the X-Ray Emission from the Jet of 3C 273
Murray, S. S.; Mathur, S.; Drake, J. J. +12 more
We present images from five observations of the quasar 3C 273 with the Chandra X-Ray Observatory. The jet has at least four distinct features that are not resolved in previous observations. The first knot in the jet (A1) is very bright in X-rays. Its X-ray spectrum is well fitted with a power law with α=0.60+/-0.05 (where Sν~ν-α
The Distance to the Vela Pulsar Gauged with Hubble Space Telescope Parallax Observations
Caraveo, P. A.; Bignami, G. F.; De Luca, A. +1 more
The distance to the Vela pulsar (PSR B0833-45) has been traditionally assumed to be 500 pc. Although affected by a significant uncertainty, this value stuck to both the pulsar and the supernova remnant. In an effort to obtain a model-free distance measurement, we have applied high-resolution astrometry to the pulsar V~23.6 optical counterpart. Usi…
The Line-of-Sight Depth of Populous Clusters in the Small Magellanic Cloud
Piatti, Andrés E.; Sarajedini, Ata; Geisler, Doug +4 more
We present an analysis of age, metal abundance, and positional data on populous clusters in the Small Magellanic Cloud (SMC) with the ultimate aim of determining the line-of-sight (LOS) depth of the SMC by using these clusters as proxies. Our data set contains 12 objects and is limited to clusters with the highest-quality data for which the ages a…
The Shape and Orientation of the Homunculus Nebula Based on Spectroscopic Velocities
Hillier, D. J.; Smith, Nathan; Gull, Theodore R. +2 more
Doppler velocities give information about the three-dimensional shape and orientation of the bipolar ejecta of η Car. We report slit spectroscopy obtained using the Space Telescope Imaging Spectrograph (HST/STIS), with spatial resolution adequate for good models. These data allow an independent estimate of the distance to this object. Equatorial v…
Early results from the Whisper instrument on Cluster: an overview
André, M.; Krasnoselskikh, V.; Fergeau, P. +22 more
The Whisper instrument yields two data sets: (i) the electron density determined via the relaxation sounder, and (ii) the spectrum of natural plasma emissions in the frequency band 2-80 kHz. Both data sets allow for the three-dimensional exploration of the magnetosphere by the Cluster mission. The total electron density can be derived unambiguousl…
The XMM-Newton view of stellar coronae: X-ray spectroscopy of the corona of AB Doradus
Haberl, F.; Mewe, R.; Audard, M. +6 more
We report results of deep X-ray observations of