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Jet-Gas Interactions in Markarian 78. I. Morphology and Kinematics
Wilson, Andrew S.; Whittle, Mark
We present a detailed study of the Seyfert 2 galaxy Markarian 78, using continuum and emission-line images and multiaperture spectra from the Hubble Space Telescope (HST) and a deep 3.6 cm VLA image. Our overall aim is to study the interaction between the radio source and the emission-line gas, since ground-based data already indicate the presence…
Absolute Proper Motion of the Fornax Dwarf Spheroidal Galaxy from Photographic and Hubble Space Telescope WFPC2 Data
Majewski, Steven R.; Keeney, Brian A.; Girard, Terrence M. +1 more
We have measured the absolute proper motion of the Fornax dwarf spheroidal galaxy from a combination of photographic plate material and Hubble Space Telescope Wide Field Planetary Camera 2 data that provide a time baseline of up to 50 yr. The extragalactic reference frame consists of eight QSO images and 48 galaxies. The absolute proper motion is …
Speckle Observations of Binary Stars with the WIYN Telescope. IV. Differential Photometry
Horch, Elliott P.; van Altena, William F.; Meyer, Reed D.
Five hundred seventy-six magnitude difference measures are presented for 260 binary stars. These measures are derived from CCD-based speckle observations taken at the WIYN 3.5 m telescope at Kitt Peak National Observatory during the period 1997-2000. Separations of the systems range from over 1" down to near the diffraction limit of the telescope.…
The Stellar Content of the Southern Tail of NGC 4038/4039 and a Revised Distance
Rich, R. Michael; Saviane, Ivo; Hibbard, J. E.
We have used the Hubble Space Telescope and Wide Field Planetary Camera 2 to image the putative tidal dwarf galaxy located at the tip of the Southern tidal tail of NGC 4038/4039, the Antennae. We resolve individual stars and identify two stellar populations. Hundreds of massive stars are present, concentrated into tight OB associations on scales o…
Radial Velocity Studies of Close Binary Stars. IX.
Rucinski, Slavek M.; Capobianco, Christopher C.; DeBond, Heide +8 more
Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the eighth set of 10 close binary systems: AB And, V402 Aur, V445 Cep, V2082 Cyg, BX Dra, V918 Her, V502 Oph, V1363 Ori, KP Peg, and V335 Peg. Half of the systems (V445 Cep, V2082 Cyg, V918 Her, V1363 Ori, and V335 Peg) were discovered photometric…
A Hubble Space Telescope WFPC2 Investigation of the Disk-Halo Interface in NGC 891
Norman, Colin A.; Dettmar, Ralf-Jürgen; Rossa, Jörn +1 more
We present deep narrowband observations with high spatial resolution of extraplanar diffuse ionized gas in the halo of NGC 891, obtained with the WFPC2 on board the HST. Our Hα observations, centered on the northern part of NGC 891, reveal an extended gaseous halo, which fills almost the entire field of view of our WFPC2 observation. Whereas NGC 8…
Unraveling the Helix Nebula: Its Structure and Knots
O'Dell, C. R.; Meixner, Margaret; McCullough, Peter R.
Through Hubble Space Telescope (HST) imaging of the inner part of the main ring of the Helix Nebula, together with CTIO 4 m images of the fainter outer parts, we have a view of unprecedented quality of the nearest bright planetary nebula. These images have allowed us to determine that the main ring of the nebula is composed of an inner disk of abo…
Direct Measurement of the Size of the Large Kuiper Belt Object (50000) Quaoar
Brown, Michael E.; Trujillo, Chadwick A.
We imaged the recently discovered bright Kuiper belt object (50000) Quaoar with the Hubble Space Telescope High Resolution Camera to directly determine its size. The point-spread function (PSF) of each of 16 images was carefully measured from a field star 13" from Quaoar, and the expected PSF at the location of Quaoar was convolved with Quaoar's m…
Weak Lensing from Space. II. Dark Matter Mapping
Refregier, Alexandre; Ellis, Richard; Massey, Richard +8 more
We study the accuracy with which weak-lensing measurements could be made from a future space-based survey, predicting the subsequent precision of three-dimensional dark matter maps, projected two-dimensional dark matter maps, and mass-selected cluster catalogs. As a baseline, we use the instrumental specifications of the SuperNova/Acceleration Pro…
The Southern Proper Motion Program. III. A Near-Complete Catalog to V=17.5
Girard, Terrence M.; van Altena, William F.; López, Carlos E. +3 more
We present the third installment of the Yale/San Juan Southern Proper Motion Catalog, SPM3. Absolute proper motions, positions, and photographic BV photometry are given for roughly 10.7 million objects, primarily stars, down to a magnitude of V=17.5. The catalog covers an irregular area of 3700 deg2, between the declinations of -20° and…