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Metrology of angles in astronomy
Kovalevsky, Jean
In astronomy, measurements of angles play a major role. After defining the units in use in astronomy, three methods of measuring angles are presented, with an application to the transit instrument. The interferometric techniques for measuring large angles are described in optical and radio wavelengths. Due to the atmospheric and mechanical limitat…
Some comments on the F ring-Prometheus-Pandora environment
Winter, O. C.; Giuliatti Winter, S. M.
The system formed by the F ring and two close satellites, Prometheus and Pandora, has been analysed since the time that Voyager visited the planet Saturn. During the ring plane crossing in 1995 the satellites were found in different positions as predicted by the Voyager data. Besides the mutual effects of Prometheus and Pandora, they are also dist…
The O VI and C III Lines at 1032 and 977 Å in Hyades F Stars
Robinson, Richard D.; Carpenter, Kenneth G.; Böhm-Vitense, Erika
We continue our investigations into the mechanisms heating the outer layers of cool dwarf stars. In this study we specifically seek to determine whether in the layers with temperatures around 250,000-300,000 K, in which the O VI lines are emitted, the temperatures are determined by heat conduction from the coronae or by the same processes that hea…
A synthetic view on structure and evolution of the Milky Way
Reylé, C.; Robin, A. C.; Derrière, S. +1 more
Since the Hipparcos mission and recent large scale surveys in the optical and the near-infrared, new constraints have been obtained on the structure and evolution history of the Milky Way. The population synthesis approach is a useful tool to interpret such data sets and to test scenarios of evolution of the Galaxy. We present here new constraints…
Cosmological Results from High-z Supernovae
Filippenko, Alexei V.; Garnavich, Peter; Riess, Adam G. +22 more
The High-z Supernova Search Team has discovered and observed eight new supernovae in the redshift interval z=0.3-1.2. These independent observations, analyzed by similar but distinct methods, confirm the results of Riess and Perlmutter and coworkers that supernova luminosity distances imply an accelerating universe. More importantly, they extend t…
A test of general relativity using radio links with the Cassini spacecraft
Iess, L.; Tortora, P.; Bertotti, B.
According to general relativity, photons are deflected and delayed by the curvature of space-time produced by any mass. The bending and delay are proportional to γ + 1, where the parameter γ is unity in general relativity but zero in the newtonian model of gravity. The quantity γ - 1 measures the degree to which gravity is not a purely geometric e…
New Constraints on ΩM, ΩΛ, and w from an Independent Set of 11 High-Redshift Supernovae Observed with the Hubble Space Telescope
Panagia, N.; Wang, L.; Sullivan, M. +45 more
We report measurements of ΩM, ΩΛ, and w from 11 supernovae (SNe) at z=0.36-0.86 with high-quality light curves measured using WFPC2 on the Hubble Space Telescope (HST). This is an independent set of high-redshift SNe that confirms previous SN evidence for an accelerating universe. The high-quality light curves available from …
Rest-Frame Ultraviolet Spectra of z~3 Lyman Break Galaxies
Pettini, Max; Shapley, Alice E.; Steidel, Charles C. +1 more
We present the results of a systematic study of the rest-frame UV spectroscopic properties of Lyman break galaxies (LBGs). The database of almost 1000 LBG spectra proves useful for constructing high signal-to-noise composite spectra. The composite spectrum of the entire sample reveals a wealth of features attributable to hot stars, H II regions, d…
SINGS: The SIRTF Nearby Galaxies Survey
Kewley, Lisa J.; Gordon, Karl D.; Calzetti, Daniela +20 more
The SIRTF Nearby Galaxy Survey is a comprehensive infrared imaging and spectroscopic survey of 75 nearby galaxies. Its primary goal is to characterize the infrared emission of galaxies and their principal infrared-emitting components, across a broad range of galaxy properties and star formation environments. SINGS will provide new insights into th…
The INTEGRAL mission
Sunyaev, R.; Mas-Hesse, J. M.; Gehrels, N. +17 more
The ESA observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory) is dedicated to the fine spectroscopy (2.5 keV FWHM @ 1 MeV) and fine imaging (angular resolution: 12 arcmin FWHM) of celestial gamma-ray sources in the energy range 15 keV to 10 MeV with concurrent source monitoring in the X-ray (3-35 keV) and optical (V-band, 550 nm) …