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Search Results: 1 - 10 of 2377 matches for " the UIT Science Team "
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Luminosities and Star Formation Rates Of Galaxies Observed With the Ultraviolet Imaging Telescope: A Comparison of Far-UV, H-alpha, and Far-IR Diagnostics
Michael N. Fanelli,Theodore P. Stecher,the UIT Science Team
Physics , 1996, DOI: 10.1063/1.52770
Abstract: During the UIT/Astro Spacelab missions, the Ultraviolet Imaging Telescope obtained spatially resolved far-UV (lambda 1500 A) imagery of ~35 galaxies exhibiting recent massive star formation. The sample includes disk systems, irregular, dwarf, and blue compact galaxies. The objects span an observed FUV luminosity range from -17 to -22 magnitudes. We estimate global star formation rates by comparing the observed FUV fluxes to the predictions of stellar population models, and compare the FUV-derived astration rates to those derived from H-alpha and far-IR photometry.
Ultraviolet Imaging Telescope (UIT) Observations of the SMC
Robert H. Cornett,Theodore P. Stecher,the UIT Science Team
Physics , 1996,
Abstract: A mosaic of four UIT far-UV (FUV; 1620A) images, which covers most of the SMC bar, is presented, with derived stellar and HII region photometry. The UV morphology of the SMC's Bar shows that recent star formation there has left striking features including: a) four concentrations of UV-bright stars spread from northeast to southwest at nearly equal (~30 arcmin=0.5 kpc) spacings; b) one concentration comprising a well-defined 8-arcmin diameter ring surrounded by a larger H-alpha ring, suggestive of sequential star formation. FUV PSF photometry is obtained for 11,306 stars, and FUV photometry is obtained for 42 H-alpha-selected HII regions, both for the stars and for the total emission contained in the apertures defined by Kennicutt & Hodge. The flux- weighted average ratio of total to stellar FUV flux is 2.15; the stellar FUV luminosity function indicates that most of the excess total flux is due to scattered FUV radiation, rather than faint stars. Both stellar and total emission are well correlated with H-alpha fluxes, and yield FUV/H-alpha ratios that are consistent with models of single-burst clusters with SMC metallicity, ages from 1-5 Myr, and moderate (E(B-V)=0.0-0.1 mag) internal SMC extinction.
UIT Astro-2 Observations of NGC 4449
Robert S. Hill,Michael N. Fanelli,Denise A. Smith,Theodore P. Stecher,the UIT Team
Physics , 1996, DOI: 10.1063/1.52826
Abstract: The bright Magellanic irregular galaxy NGC 4449 was observed by the Ultraviolet Imaging Telescope (UIT) during the Astro-2 Spacelab mission in March, 1995. Far ultraviolet (FUV) images at a spatial resolution of ~3 arcsec show bright star-forming knots that are consistent with the general optical morphology of the galaxy and are often coincident with bright H II regions. Comparison of FUV with H-alpha shows that in a few regions, sequential star formation may have occurred over the last few Myr. The bright star forming complexes in NGC 4449 are superposed on a smooth, diffuse FUV background that may be associated with the H-alpha "froth."
The Promise of Low-Frequency Gravitational Wave Astronomy
T. A. Prince,for the LISA International Science Team
Physics , 2009,
Abstract: This Astro2010 science white paper provides an overview of the opportunities in low-frequency gravitational-wave astronomy, a new field that is poised to make significant advances. While discussing the broad context of gravitational-wave astronomy, this paper concentrates on the low-frequency region (10^(-5) to 1 Hz), a frequency range abundantly populated in strong sources of gravitational waves including massive black hole mergers, ultra-compact stellar-mass galactic binaries, and capture of compact objects by massive black holes in the nuclei of galaxies.
Radial velocity follow-up for confirmation and characterization of transiting exoplanets
F. Bouchy,C. Moutou,D. Queloz,the CoRoT Exoplanet Science Team
Physics , 2009,
Abstract: Radial Velocity follow-up is essential to establish or exclude the planetary nature of a transiting companion as well as to accurately determine its mass. Here we present some elements of an efficient Doppler follow-up strategy, based on high-resolution spectroscopy, devoted to the characterization of transiting candidates. Some aspects and results of the radial velocity follow-up of the CoRoT space mission are presented in order to illustrate the strategy used to deal with the zoo of transiting candidates.
Detection limits in space-based transit observations
H. J. Deeg,F. Favata,Eddington Science Team
Physics , 2000,
Abstract: From simulations of transit observations, it is found that the detectability of extrasolar planets depends only on two parameters: The signal-to-noise ratio during a transit, and the number of data points observed during transits. All other physical parameters describing transit configurations (planet and star size, orbital period, orbital half axis, latitude of the transit across star) can be reduced to these two parameters. In turn, once the dependency between transit detectability and these two parameters has been determined, predictions for an instrument's ability to detect transits by any combination of physical parameters can be derived with ease. These predictions are applied to the Eddington proposal of a combined Astroseismology/Transit-detection space mission currently under study by ESA, which is described briefly.
Planet Detection Capabilities of the Eddington Mission
Hans J. Deeg,Keith Horne,Fabio Favata,Eddington Science Team
Physics , 2000,
Abstract: Eddington is a space mission for extrasolar planet finding and for asteroseismic observations. It has been selected by ESA as an F2/F3 reserve mission with a potential implementation in 2008-13. Here we describe Eddington's capabilities to detect extrasolar planets, with an emphasis on the detection of habitable planets. Simulations covering the instrumental capabilities of Eddington and the stellar distributions in potential target fields lead to predictions of about 10,000 planets of all sizes and temperatures, and a few tens of terrestrial planets that are potentially habitable. Implications of Eddington for future larger scale missions are briefly discussed.
The CoRoT Exoplanet program : status & results
M. Deleuil,C. Moutou,P. Bordé,the CoRoT exoplanet science team
Physics , 2011, DOI: 10.1051/epjconf/20111101001
Abstract: The CoRoT satellite is the first instrument hunting for planets from space. We will review the status of the CoRoT/Exoplanet program. We will then present the CoRoT exoplanetary systems and how they widen the range of properties of the close-in population and contribute to our understanding of the properties of planets.
Localization of GRBs by Bayesian Analysis of Data from the HETE WXM
Carlo Graziani,Donald Q. Lamb,the HETE Science Team
Physics , 2002, DOI: 10.1063/1.1579305
Abstract: We describe a new method of transient point source localization for coded-aperture X-ray detectors that we have applied to data from the HETE Wide-Field X-Ray Monitor (WXM). The method is based upon the calculation of the likelihood function and its interpretation as a probability density for the transient source location by an application of Bayes' Theorem. The method gives a point estimate of the source location by finding the maximum of this probability density, and credible regions for the source location by choosing suitable contours of constant probability density. We describe the application of this method to data from the WXM, and give examples of GRB localizations which illustrate the results that can be obtained using this method.
Results from the Wilkinson Microwave Anisotropy Probe
Eiichiro Komatsu,Charles L. Bennett,on behalf of the WMAP Science Team
Physics , 2014, DOI: 10.1093/ptep/ptu083
Abstract: The Wilkinson Microwave Anisotropy Probe (WMAP) mapped the distribution of temperature and polarization over the entire sky in five microwave frequency bands. These full-sky maps were used to obtain measurements of temperature and polarization anisotropy of the cosmic microwave background with the unprecedented accuracy and precision. The analysis of two-point correlation functions of temperature and polarization data gives determinations of the fundamental cosmological parameters such as the age and composition of the universe, as well as the key parameters describing the physics of inflation, which is further constrained by three-point correlation functions. WMAP observations alone reduced the flat $\Lambda$ cold dark matter ($\Lambda$CDM) cosmological model (six) parameter volume by a factor of >68,000 compared with pre-WMAP measurements. The WMAP observations (sometimes in combination with other astrophysical probes) convincingly show the existence of non-baryonic dark matter, the cosmic neutrino background, flatness of spatial geometry of the universe, a deviation from a scale-invariant spectrum of initial scalar fluctuations, and that the current universe is undergoing an accelerated expansion. The WMAP observations provide the strongest ever support for inflation; namely, the structures we see in the universe originate from quantum fluctuations generated during inflation.
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