Search Publications
The Dust Content and Opacity of Actively Star-forming Galaxies
Calzetti, Daniela; Storchi-Bergmann, Thaisa; Bohlin, Ralph C. +3 more
We present far-infrared (FIR) photometry at 150 and 205 µm of eight low-redshift starburst galaxies obtained with the Infrared Space Observatory (ISO) ISOPHOT. Five of the eight galaxies are detected in both wave bands, and these data are used, in conjunction with IRAS archival photometry, to model the dust emission at λ>~40 µm. The…
On the Absorption of X-Rays in the Interstellar Medium
McCray, R.; Wilms, J.; Allen, A.
We present an improved model for the absorption of X-rays in the interstellar medium (ISM) intended for use with data from future X-ray missions with larger effective areas and increased energy resolution such as Chandra and the X-Ray Multiple Mirror mission, in the energy range >~100 eV. Compared with previous work, our formalism includes rece…
The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XXVIII. Combining the Constraints on the Hubble Constant
Kelson, Daniel D.; Illingworth, Garth D.; Huchra, John P. +14 more
Since the launch of Hubble Space Telescope (HST) 9 yr ago, Cepheid distances to 25 galaxies have been determined for the purpose of calibrating secondary distance indicators. Eighteen of these have been measured by the HST Key Project team, six by the Supernova Calibration Project, and one independently by Tanvir. Collectively, this work sets out …
Multiwavelength Observations of Dusty Star Formation at Low and High Redshift
Steidel, Charles C.; Adelberger, Kurt L.
If high-redshift galaxies resemble rapidly star-forming galaxies in the local universe, most of the luminosity produced by their massive stars will have been absorbed by dust and reradiated as far-infrared photons that cannot be detected with existing facilities. This paper examines what can be learned about high-redshift star formation from the s…
Distances, Ages, and Epoch of Formation of Globular Clusters
Fusi Pecci, Flavio; Carretta, Eugenio; Clementini, Gisella +1 more
We review the results on distances and absolute ages of Galactic globular clusters (GCs) obtained after the release of the Hipparcos catalog. Several methods aimed at the definition of the Population II local distance scale are discussed, and their results compared, exploiting new results for RR Lyraes in the Large Magellanic Cloud (LMC). We find …
An Inventory of Interstellar Ices toward the Embedded Protostar W33A
van Dishoeck, E. F.; Whittet, D. C. B.; Schutte, W. A. +8 more
This paper presents, for the first time, a complete 2.4-25 µm spectrum of the dust-embedded young stellar object W33A. The spectrum was obtained with the Short Wavelength Spectrometer of the Infrared Space Observatory at a mean resolving power of ~750. The spectrum displays deep H2O ice and silicate absorptions centered at 3.0 and…
Models for Old, Metal-poor Stars with Enhanced α-Element Abundances. I. Evolutionary Tracks and ZAHB Loci; Observational Constraints
VandenBerg, Don A.; Alexander, David R.; Swenson, Fritz J. +2 more
Stellar evolutionary tracks have been computed for 17 [Fe/H] values from -2.31 to -0.30 assuming, in each case, [α/Fe]=0.0, 0.3, and 0.6. The helium abundance was assumed to vary from Y=0.2352 at [Fe/H]=-2.31 to Y=0.2550 at [Fe/H]=-0.30 and held constant for the different choices of [α/Fe] at a fixed iron content. Masses in the range 0.5<=M
On the Nature of Soft X-Ray Weak Quasi-stellar Objects
Brandt, W. N.; Laor, A.; Wills, Beverley J.
Recent studies of quasi-stellar objects (QSOs) with ROSAT suggest the existence of a significant population of soft X-ray weak QSOs (SXW QSOs) where the soft X-ray flux is ~10-30 times smaller than in typical QSOs. Why are these QSOs soft X-ray weak, and what is their relationship to broad absorption line QSOs (BAL QSOs) and X-ray warm absorber QS…
The Evolution of the Galactic Morphological Types in Clusters
Couch, Warrick J.; Poggianti, Bianca M.; Fasano, Giovanni +3 more
The morphological types of galaxies in nine clusters in the redshift range 0.1<~z<~0.25 are derived from very good seeing images taken at the NOT and the La Silla-Danish telescopes, with all galaxies at MV<-20 and within the central ~1 Mpc2 area being classified. With the purpose of investigating the evolution of the…
Hubble Space Telescope Photometry and Keck Spectroscopy of the Rich Cluster MS 1054-03: Morphologies, Butcher-Oemler Effect, and the Color-Magnitude Relation at Z = 0.83
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +2 more
We present a study of 81 I-band selected, spectroscopically confirmed members of the X-ray cluster MS 1054-03 at z=0.83. Redshifts and spectral types were determined from Keck spectroscopy. Morphologies and accurate colors were determined from a large mosaic of HST WFPC2 images in RF606W and IF814W, corresponding to U and B i…