Search Publications
Mass-losing Semiregular Variable Stars in Baade's Windows
Genzel, R.; Alard, C.; Blommaert, J. A. D. L. +38 more
By cross-correlating the results of two recent large-scale surveys, the general properties of a well-defined sample of semiregular variable stars have been determined. ISOGAL mid-infrared photometry (7 and 15 µm) and MACHO V and R light curves are assembled for approximately 300 stars in the Baade's windows of low extinction toward the Galac…
Oxygen Abundances in Metal-poor Stars (-2.2<[Fe/H]<-1.2) from Infrared OH Lines
Meléndez, Jorge; Barbuy, Beatriz; Spite, François
Infrared OH lines at 1.55-1.56 µm in the H band were obtained with the Phoenix high-resolution spectrograph at the 2.1 m telescope of the Kitt Peak National Observatory for a sample of 14 metal-poor stars. Detailed analyses of the sample stars have been carried out, deriving stellar parameters based on two methods: (a) spectroscopic paramete…
Intrinsic and Reprocessed Optical Emission from the Companion to PSR J2051-0827
Kulkarni, S. R.; van Kerkwijk, M. H.; Stappers, B. W. +1 more
Hubble Space Telescope observations of the companion to the eclipsing millisecond pulsar PSR J2051-0827 have revealed its ``dark'' side. The R magnitude at minimum is ~26, while the difference between the side heated by the impinging pulsar radiation and the unirradiated side is ~3.3 mag. For the first time, these data show that there is an asymme…
Cepheid Calibration of the Peak Brightness of Type IA Supernovae. X. SN 1991T in NGC 4527
Panagia, N.; Saha, A.; Labhardt, Lukas +5 more
Repeated imaging observations have been made of NGC 4527 with the Hubble Space Telescope between 1999 April and June, over an interval of 69 days. Images were obtained on 12 epochs in the F555W band and on five epochs in the F814W band. The galaxy hosted the Type Ia supernova SN 1991T, which showed relatively unusual behavior by having both an abn…
Detection of High-Latitude Waves of Solar Coronal Activity in Extreme-Ultraviolet Data from the Solar and Heliospheric Observatory EUV Imaging Telescope
Kosovichev, A. G.; Benevolenskaya, E. E.; Scherrer, P. H.
We present the results of an investigation of EUV coronal structures in 1996-2000 using the Solar and Heliospheric Observatory EIT data in 171, 195, 284, and 304 Å lines. During this period, poleward- and equatorward-migrating waves of solar activity have been found in axisymmetrical distributions of EUV intensity in all four lines. In the axisymm…
Color-Magnitude Diagram and Luminosity Function of M4 near the Hydrogen-burning Limit
Anderson, Jay; Bedin, Luigi R.; Piotto, Giampaolo +1 more
A proper-motion separation of M4 members from field stars, using deep Hubble Space Telescope observations separated by a time baseline of 5 yr, allows us to study a pure sample of cluster main-sequence stars almost to the minimum mass for hydrogen burning. High-precision photometry shows how badly current theoretical models fail to reproduce the c…
The Multitude of Unresolved Continuum Sources at 1.6 Microns in Hubble Space Telescope Images of Seyfert Galaxies
Rieke, G. H.; Alonso-Herrero, A.; Quillen, A. C. +4 more
We examine 112 Seyfert galaxies observed by the Hubble Space Telescope at 1.6 µm. We find that ~50% of the Seyfert 2.0 galaxies which are part of the Revised Shapely-Ames (RSA) Catalog or the CfA redshift sample contain unresolved continuum sources at 1.6 µm. All but a couple of the Seyfert 1.0-1.9 galaxies display unresolved continuum…
B1359+154: A Six-Image Lens Produced by a z ~= 1 Compact Group of Galaxies
Peng, C. Y.; Keeton, C. R.; Kochanek, C. S. +8 more
Hubble Space Telescope (HST) V- and I-band observations show that the gravitational lens B1359+154 consists of six images of a single zs=3.235 radio source and its star-forming host galaxy, produced by a compact group of galaxies at zl~=1. Very Long Baseline Array (VLBA) observations at 1.7 GHz strongly support this conclusio…
Far Ultraviolet Spectroscopic Explorer Observations of Molecular Hydrogen in Translucent Interstellar Clouds. II. The Line of Sight toward HD 110432
York, Donald G.; Roueff, E.; Shull, J. Michael +7 more
We report the second study from the FUSE survey of molecular hydrogen in translucent clouds for the line of sight toward HD 110432. This star lies beyond the Coalsack dark nebula, and, with E(B-V)=0.40 and AV=1.32, this line of sight bridges the gap between less-extinguished diffuse-cloud lines of sight with AV~1, such as ζ O…
The Infrared Surface Brightness Fluctuation Hubble Constant
Lauer, Tod R.; Ajhar, Edward A.; Rieke, Marcia J. +5 more
We measured infrared surface brightness fluctuation (SBF) distances to an isotropically distributed sample of 16 distant galaxies with redshifts reaching 10,000 km s-1 using the near-IR camera and multiobject spectrometer (NICMOS) on the Hubble Space Telescope (HST). The excellent spatial resolution, very low background, and brightness …