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 Tycho-2 catalogue of the 2.5 million brightest stars
Makarov, V. V.; Bastian, U.; Fabricius, C. +6 more
The Tycho-2 Catalogue presented here is an astrometric reference catalogue containing positions and proper motions as well as two-colour photometric data for the 2.5 million brightest stars in the sky. The Tycho-2 positions and magnitudes are based on precisely the same observations as the original Tycho Catalogue (hereafter Tycho-1) collected by …
WFPC2 Stellar Photometry with HSTPHOT
Dolphin, Andrew E.
HSTphot, a photometry package designed to handle the undersampled point-spread functions (PSFs) found in WFPC2 images, is introduced and described, as well as some of the considerations that have to be made in order to obtain accurate PSF-fitting stellar photometry with WFPC2 data. Tests of HSTphot's internal reliability are made using multiple ob…
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 …
The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution
Dehnen, Walter
Hydrodynamic modeling of the inner Galaxy suggests that the radius of the outer Lindblad resonance (OLR) of the Galactic bar lies in the vicinity of the Sun. How does this resonance affect the distribution function in the outer parts of a barred disk, and can we identify any effect of the resonance in the velocity distribution actually observed in…
Interplanetary acceleration of coronal mass ejections
St. Cyr, O. C.; Kaiser, M. L.; Gopalswamy, N. +3 more
Using an observed relation between speeds of CMEs near the Sun and in the solar wind, we determine an “effective” acceleration acting on the CMEs. We found a linear relation between this effective acceleration and the initial speed of the CMEs. The acceleration is similar to that of the slow solar wind in magnitude. The average solar wind speed na…
Composition of quasi-stationary solar wind flows from Ulysses/Solar Wind Ion Composition Spectrometer
Geiss, J.; Wimmer-Schweingruber, R. F.; Schwadron, N. A. +6 more
Using improved, self-consistent analysis techniques, we determine the average solar wind charge state and elemental composition of nearly 40 ion species of He, C, N, O, Ne, Mg, Si, S, and Fe observed with the Solar Wind Ion Composition Spectrometer on Ulysses. We compare results obtained during selected time periods, including both slow solar wind…
Abundances and Kinematics of Field Halo and Disk Stars. I. Observational Data and Abundance Analysis
Fulbright, Jon P.
We describe observations and abundance analysis of a high-resolution, high signal-to-noise ratio survey of 168 stars, most of which are metal-poor dwarfs. We follow a self-consistent LTE analysis technique to determine the stellar parameters and abundances, and we estimate the effects of random and systematic uncertainties on the resulting abundan…
Properties of coronal mass ejections: SOHO LASCO observations from January 1996 to June 1998
St. Cyr, O. C.; Plunkett, S. P.; Michels, D. J. +9 more
We report the properties of all the 841 coronal mass ejections (CMEs) observed by the Solar and Heliospheric Observatory (SOHO) Large Angle Spectroscopic Coronagraph (LASCO) C2 and C3 white-light coronagraphs from January 1996 through June 1998, and we compare those properties to previous observations by other similar instruments. Both the CME rat…