Search Publications
The symbiotic binary system RX Puppis: a possible recurrent nova with a Mira companion
Whitelock, Patricia A.; Barba, Rodolfo; Hack, Warren +4 more
We present an analysis of photometric and spectroscopic observations of the symbiotic binary system RX Pup with the aim of developing a reliable binary model for the system and identifying mechanisms responsible for its spectacular activity. The binary is composed of a long-period Mira variable surrounded by a thick dust shell and a hot ~ 0.8 M_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…
On the Origins of Starburst and Poststarburst Galaxies in Nearby Clusters
Caldwell, Nelson; Rose, James A.; Dendy, Kristi
Hubble Space Telescope (HST) Wide Field Planetary Camera 2 images in B (F450W) and I (F814W) have been obtained for three starburst (SB) and two poststarburst (PSB) galaxies in the Coma Cluster and for three such galaxies in the cluster DC 048-52. V (F555W) and I images for an additional PSB galaxy in Coma have been extracted from the HST archive.…
Heliospheric and it astrospheric hydrogen absorption towards Sirius: no need for interstellar hot gas
Lallement, R.; Izmodenov, V. V.; Malama, Y. G.
We use an updated self-consistent kinetic/gasdynamic model of the solar wind/interstellar flow interaction to compute the Lyman-alpha absorption by hydrogen atoms of both interstellar and solar origin generated in the heliospheric interface. We apply this model to the direction of the star Sirius. We show that the neutralized, compressed solar win…
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…
The Extended Blue Continuum and Line Emission around the Central Radio Galaxy in Abell 2597
Koekemoer, Anton M.; Baum, Stefi A.; O'Dea, Christopher P. +5 more
We present results from detailed imaging of the centrally dominant radio elliptical galaxy in the cooling-flow cluster Abell 2597, using data obtained with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). This object is one of the archetypal ``blue-lobed'' cooling-flow radio elliptical galaxies, also displaying a …
The 1995-96 decline of R Coronae Borealis: high-resolution optical spectroscopy
Hatzes, Artie P.; Lambert, David L.; Pandey, Gajendra +10 more
A set of high-resolution optical spectra of R CrB acquired before, during and after its 1995-96 decline is discussed. All of the components reported from earlier declines are seen. This novel data set provides new information on these components including several aspects not previously seen in declines of R CrB and other R Coronae Borealis stars. …