Search Publications
Internal Kinematics of Blue Canada-France Redshift Survey Galaxies at Z ~ 0.6
Crampton, David; Schade, David; Mallén-Ornelas, Gabriela +1 more
We present the results of a study of the internal kinematics of luminous star-forming galaxies in the 0<z<0.8 range, with the aim of investigating the nature of the blue galaxies that cause the largest changes in the luminosity function at z>=0.5. New kinematic data are analyzed for a sample of 24 galaxies from the Canada-France Redshift …
Hubble Space Telescope Observations of the Host Galaxies of BL Lacertae Objects
Giavalisco, Mauro; Urry, C. Megan; Scarpa, Riccardo +3 more
Six BL Lac objects from the complete 1 Jy radio-selected sample of 34 objects were observed in cycle 5 with the Hubble Space Telescope (HST) Wide-Field Planetary Camera 2 (WFPC2) to an equivalent limiting flux of µI~26 mag arcsec-2. Here we report results for the second half of this sample, as well as new results for th…
The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XX. The Discovery of Cepheids in the Virgo Cluster Galaxy NGC 4548
Kelson, Daniel D.; Illingworth, Garth D.; Madore, Barry F. +19 more
We report on the discovery and properties of Cepheid variable stars in the barred spiral galaxy NGC 4548, which is a member of the Virgo cluster of galaxies. This is one of the galaxies being observed as part of the Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale, which aims to determine the Hubble constant to 10% accu…
Morphology and Composition of the Helix Nebula
Dufour, R. J.; Henry, R. B. C.; Kwitter, K. B.
We present new narrowband filter imagery in Hα and [N II] λ6584, along with UV and optical spectrophotometry measurements from 1200 to 9600 Å of NGC 7293, the Helix Nebula, a nearby, photogenic planetary nebula of large diameter and low surface brightness. Detailed models of the observable ionized nebula support the recent claim that the Helix is …
A Semiempirical Model of the Infrared Universe
Tan, Jonathan C.; Silk, Joe; Balland, Christophe
We present a simple model of the infrared universe, based as much as possible on local observations. We model the luminosity and number evolution of disk and starburst galaxies, including the effects of dust, gas, and spectral evolution. Although simple, our approach is able to reproduce observations of galaxy number counts and the infrared and su…
Jets, Knots, and Tails in Planetary Nebulae: NGC 3918, K1-2, and Wray 17-1
Corradi, Romano L. M.; Gonçalves, Denise R.; Villaver, Eva +2 more
We analyze optical images and high-resolution, long-slit spectra of three planetary nebulae that possess collimated, low-ionization features. NGC 3918 is composed of an inner, spindle-shaped shell mildly inclined with respect to the plane of the sky. Departing from the polar regions of this shell, we find a two-sided jet expanding with velocities …
Star Clusters in M33. II. Global Properties
Chandar, Rupali; Bianchi, Luciana; Ford, Holland C.
We discuss the global physical properties of stellar clusters in M33 and compare them with LMC cluster properties. In a companion paper (Paper I) we have compiled the first unbiased, representative sample of star clusters for this galaxy from Hubble Space Telescope WFPC2 multiband images of 20 fields in M33, sampling a variety of environments from…
Meridional Flows from Ring Diagram Analysis
González Hernández, I.; Bogart, R. S.; Patrón, J. +1 more
In order to search for meridional circulation in the solar envelope, we have applied ring diagram analysis to a set of small regions over the surface. The helioseismic data consist of Solar Oscillation Investigation/Michelson Doppler Imager Dopplergrams taken over a time span of about 50 hr (~3000 images) on 1998 June 20-22. The regions studied co…
The Faint Optical Stellar Luminosity Function in the Ursa Minor Dwarf Spheroidal Galaxy
Wyse, Rosemary F. G.; Gilmore, Gerard; Feltzing, Sofia
Analyses of their internal stellar kinematics imply that the dwarf spheroidal (dSph) companion galaxies to the Milky Way are among the most dark matter-dominated systems known. Should there be significant dark matter in the form of faint stars in these systems, the stellar luminosity function must be very different from that of a similar metallici…
The Misdirected Central Engine of the Hyperluminous Infrared Galaxy and Type 2 QSO IRAS P09104+4109
Hines, Dean C.; Schmidt, Gary D.; Smith, Paul S. +2 more
Hubble Space Telescope Wide-Field Planetary Camera 2 imaging polarimetry of the hyperluminous infrared galaxy (and misdirected QSO) IRAS P09104+4109 reveals a highly polarized (p~20%) giant (~5 kpc) bipolar reflection nebula centered on the nucleus. This, together with our previous detection of broad, polarized Mg II and newly detected broad, pola…