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Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. I. Method and a Preliminary Measurement for Fornax
Minniti, Dante; Mateo, Mario; Piatek, Slawomir +6 more
This article presents and discusses a method for measuring the proper motions of the Galactic dwarf spheroidal galaxies using images taken with the Hubble Space Telescope. The method involves fitting an effective point-spread function to the image of a star or quasi-stellar object to determine its centroid with an accuracy of about 0.005 pixels (0…
Galaxies with a Central Minimum in Stellar Luminosity Density
Filippenko, Alexei V.; Ho, Luis C.; van der Marel, Roeland P. +15 more
We used Hubble Space Telescope WFPC2 images to identify six early-type galaxies with surface brightness profiles that decrease inward over a limited range of radii near their centers. The inferred luminosity density profiles of these galaxies have local minima interior to their core break radii. NGC 3706 harbors a high surface brightness ring of s…
New Members of the Cluster Family in Nearby Lenticular Galaxies
Brodie, Jean P.; Larsen, Søren S.
Using spectra obtained with the Keck I Telescope, we have demonstrated conclusively that the faint (23<=V<=24 mag) and unusually extended objects we discovered in Hubble Space Telescope images of the lenticular galaxies NGC 1023 and NGC 3384 are star clusters associated with their respective galaxies. In the case of NGC 1023, we were further…
The Chandra Deep Field North Survey. X. X-Ray Emission from Very Red Objects
Hornschemeier, A. E.; Alexander, D. M.; Bauer, F. E. +4 more
The multiwavelength properties of very red objects [VROs; (I-K)>=4] are largely unknown since many of these sources are optically faint (I>=24) and undetected at most wavelengths. Here we provide constraints on the X-ray (0.5-8.0 keV) properties of VROs using the 1 Ms Chandra exposure of an 8.4‧×8.4‧ region within the Hawaii flanking-field a…
The Embedded Super-Star Cluster of SBS 0335-052
Sauvage, Marc; Plante, Stéphanie
We analyze the infrared (6-100 µm) spectral energy distribution of the blue compact dwarf and metal-poor (Z=Zsolar/41) galaxy SBS 0335-052. With the help of DUSTY, a program that solves the radiation transfer equations in a spherical environment, we evaluate that the infrared emission of SBS 0335-052 is produced by an embedded sup…
Hubble Space Telescope STIS Observations of the Kinematics of Emission-Line Nebulae in Three Compact Steep-Spectrum Radio Sources
Koekemoer, Anton M.; Baum, Stefi A.; O'Dea, Christopher P. +8 more
We have obtained Hubble Space Telescope Space Telescope Imaging Spectrograph long-slit spectroscopy of the aligned emission-line nebulae in three compact steep-spectrum radio sources: 3C 67, 277.1, and 303.1. We find systematic offsets (~300-500 km s-1) of the emission-line velocities on one or both sides of the radio sources. We also s…
Cepheids and Long-Period Variables in IC 342
Saha, A.; Hoessel, J. G.; Claver, J.
Using repeated imaging with the WIYN 3.5 m telescope at Kitt Peak, we have identified 24 Cepheids in IC 342. For 20 of them, we have obtained reliable r and i photometry. In addition, we have identified 52 other variables (with varying degrees of data quality) for which we are unable to derive definite periods from the data at hand. Most of these …
Massive Star Formation in Luminous Infrared Galaxies: Giant H II Regions and Their Relation to Super-Star Clusters
Rieke, George H.; Alonso-Herrero, Almudena; Rieke, Marcia J. +1 more
We have used Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer broadband (at 1.6 µm) and narrowband Paα (λrest=1.87 µm) images to identify, respectively, star clusters and H II regions in a sample of eight luminous infrared galaxies (LIRGs). These observations have revealed the presence of a large pop…
Speckle Observations of Binary Stars with the WIYN Telescope. II. Relative Astrometry Measures during 1998-2000
Horch, Elliott P.; van Altena, William F.; Ninkov, Zoran +3 more
Five hundred twelve relative astrometry measures are presented for 253 double stars, including 53 double stars discovered by Hipparcos. In 15 cases, relative astrometry is reported for the first time for newly confirmed pairs. In addition, 20 high-quality nondetections of companions are reported for stars suspected of being nonsingle by Hipparcos.…
The Interacting Dwarf Galaxy NGC 3077: The Interplay of Atomic and Molecular Gas with Violent Star Formation
Scoville, Nick; Walter, Fabian; Martin, Crystal +1 more
We present a comprehensive multiwavelength study of the nearby interacting dwarf galaxy NGC 3077 (member of the M81 triplet). High-resolution VLA H I observations show that most of the atomic gas (~90%) around NGC 3077 is situated in a prominent tidal arm with a complex velocity structure. Little H I (~5×107 Msolar) is associ…