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A Radio Study of the Seyfert Galaxy IC 5063: Evidence for Fast Gas Outflow
Tsvetanov, Z.; Morganti, R.; Oosterloo, T.
We present new radio continuum (8 and 1.4 GHz) and H i 21 cm line observations of the Seyfert 2 galaxy IC 5063 (PKS 2048-572), obtained with the Australia Telescope Compact Array. The high-resolution 8 GHz image reveals a linear triple structure ~4" (1.3 kpc) in size. This small-scale radio emission shows a strong morphological association with th…
A Study of Nine High-Redshift Clusters of Galaxies. II. Photometry, Spectra, and Ages of Clusters 0023+0423 and 1604+4304
Postman, Marc; Lubin, Lori M.; Oke, J. B.
We present an extensive photometric and spectroscopic study of two high-redshift clusters of galaxies based on data obtained from the Keck 10 m telescopes and the Hubble Space Telescope. The clusters Cl 0023+0423 (z = 0.84) and Cl 1604+4304 (z = 0.90) are part of a multiwavelength program of Oke, Postman & Lubin to study nine candidate cluster…
Photometry of Proxima Centauri and Barnard's Star Using Hubble Space Telescope Fine Guidance Sensor 3: A Search for Periodic Variations
Hemenway, P. D.; Jefferys, W. H.; Nelan, E. +10 more
We have observed Proxima Centauri and Barnard's star with the Hubble Space Telescope Fine Guidance Sensor 3. Proxima Cen exhibits small-amplitude, periodic photometric variations. Once several sources of systematic photometric error are corrected, we obtain 2 mmag internal photometric precision. We identify two distinct behavior modes over the pas…
Modeling the Brightness Profiles of the Orion Proplyds
Henney, W. J.; Arthur, S. J.
We investigate whether simple models of a photoevaporated flow from an externally ionized neutral clump or wind can reproduce the observed Hα intensity profiles of the proplyds in the inner Orion Nebula. We find that models fitted to the bright ``cusp'' at the head of each proplyd successfully predict the brightness distribution of the extended di…
Keck HIRES Spectroscopy of M92 Subgiants: Surprising Abundances near the Turnoff
King, Jeremy R.; Boesgaard, Ann M.; Stephens, Alex +1 more
Using high-resolution, moderate signal-to-noise ratio spectroscopy obtained with the 10 m Keck I Telescope and efficient HIRES echelle spectrograph, we derive abundances of several elements in subgiants near the M92 turnoff. As a consistency check, we also analyze the metal-poor field star HD 140283 and find an Fe abundance in fine agreement with …
Early Evolution of the Galactic Halo Revealed from Hipparcos Observations of Metal-poor Stars
Yoshii, Yuzuru; Chiba, Masashi
The kinematics of 122 red giant and 124 RR Lyrae stars in the solar neighborhood are studied using accurate measurements of their proper motions obtained by the Hipparcos astrometry satellite, combined with their published photometric distances, metal abundances, and radial velocities. A majority of these sample stars have metal abundances of [Fe/…
Hubble Space Telescope Observations of the Draco Dwarf Spheroidal Galaxy
Ballester, Gilda E.; Crisp, David; Grillmair, Carl J. +15 more
We present an F606W-F814W color-magnitude diagram for the Draco dwarf spheroidal galaxy based on Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) images. The luminosity function is well sampled to ~3 mag below the turnoff. We see no evidence for multiple turnoffs and conclude that, at least over the field of view of the WFPC2, star for…
A Wide Field Planetary Camera 2 Study of the Resolved Stellar Population of the Pegasus Dwarf Irregular Galaxy (DDO 216)
Saha, A.; Mateo, M.; Gallagher, J. S. +5 more
The stellar population of the Pegasus dwarf irregular galaxy is investigated in images taken in the F439W (B), F555W (V), and F814W (I) bands with the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope. With WFPC2 the Pegasus dwarf is highly resolved into individual stars to limiting magnitudes of about 25.5 in B and V and 25 in I…
Deep Hubble Space Telescope Observations of Star Clusters in NGC 1275
Ballester, Gilda E.; Crisp, David; Grillmair, Carl J. +15 more
We present an analysis of compact star clusters in deep Hubble Space Telescope Wide Field Planetary Camera 2 images of NGC 1275. B- and R-band photometry of roughly 3000 clusters shows a bimodality in the B - R colors, suggesting that distinct old and young cluster populations are present. The small spread in the colors of the blue clusters is con…
Spatially Resolved Hubble Space Telescope Spectra of the Chromosphere of alpha Orionis
Dupree, A. K.; Gilliland, R. L.; Uitenbroek, H.
Spatially resolved UV spectra of the supergiant alpha Orionis (Betelgeuse) obtained in 1995 March with the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope (HST) show that the chromospheric emission in the Mg II h and k (around 280 nm) lines reaches a diameter of at least ~270 milliarcseconds, about twice the size of…