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A Hubble Space Telescope Imaging Survey of Nearby Active Galactic Nuclei
Gorjian, Varoujan; Malkan, Matthew A.; Tam, Raymond
We have obtained WFPC2 images of 256 of the nearest (z <= 0.035) Seyfert 1, Seyfert 2, and starburst galaxies. Our 500 s broadband (F606W) exposures reveal much fine-scale structure in the centers of these galaxies, including dust lanes and patches, bars, rings, wisps, and filaments, and tidal features such as warps and tails. Most of this fine…
Indication, from Pioneer 10/11, Galileo, and Ulysses Data, of an Apparent Anomalous, Weak, Long-Range Acceleration
Anderson, John D.; Nieto, Michael Martin; Turyshev, Slava G. +3 more
Radio metric data from the Pioneer 10/11, Galileo, and Ulysses spacecraft indicate an apparent anomalous, constant, acceleration acting on the spacecraft with a magnitude ~8.5×10-8 cm/s2, directed towards the Sun. Two independent codes and physical strategies have been used to analyze the data. A number of potential causes ha…
Star Formation in R136: A Cluster of O3 Stars Revealed by Hubble Space Telescope Spectroscopy
Massey, Philip; Hunter, Deidre A.
The R136 cluster in 30 Doradus is the prototype ``super star cluster,'' and the only example sufficiently close that its massive star content can be studied directly. We have used the Hubble Space Telescope to obtain spectra of 65 of the bluest, most luminous stars in R136 and find that the majority of these stars are of type O3, the hottest, most…
Multipolar Bubbles and Jets in Low-Excitation Planetary Nebulae: Toward a New Understanding of the Formation and Shaping of Planetary Nebulae
Trauger, John T.; Sahai, Raghvendra
First results from a Hubble Space Telescope Wide Field Planetary Camera 2 Hα imaging survey of young planetary nebulae (PNs) are reported. The PNs have been selected on the basis of their low excitation characteristics. All objects imaged so far show highly aspherical morphology, with a majority characterized by multipolar bubbles distributed roug…
HIPPARCOS photometry of Herbig Ae/Be stars
de Winter, D.; van den Ancker, M. E.; Tjin A Djie, H. R. E.
The photometric behaviour of a sample of 44 Herbig Ae/Be (HAeBe) candidate stars was studied using a uniform set of optical photometry obtained by the Hipparcos mission. Astrophysical parameters (distance, temperature, luminosity, mass, age) of this sample of stars were derived as well by combining the astrometric data provided by Hipparcos with d…
UVCS/SOHO Empirical Determinations of Anisotropic Velocity Distributions in the Solar Corona
Romoli, M.; Raymond, J. C.; Naletto, G. +28 more
We present a self-consistent empirical model for several plasma parameters of a polar coronal hole near solar minimum, derived from observations with the Solar and Heliospheric Observatory Ultraviolet Coronagraph Spectrometer. The model describes the radial distribution of density for electrons, H0, and O5+ and the outflow ve…
Photoevaporation of Disks and Clumps by Nearby Massive Stars: Application to Disk Destruction in the Orion Nebula
Johnstone, Doug; Bally, John; Hollenbach, David
We present a model for the photoevaporation of circumstellar disks or dense clumps of gas by an external source of ultraviolet radiation. Our model includes the thermal and dynamic effects of 6-13.6 eV far-ultraviolet (FUV) photons and Lyman continuum EUV photons incident upon disks or clumps idealized as spheres of radius rd and enclos…
Auroral radio emissions at the outer planets: Observations and theories
Zarka, Philippe
We review both observational and theoretical aspects of the generation of auroral radio emissions at the outer planets, trying to organize the former in a coherent frame set by the latter. Important results have been obtained in the past few years on these radio emissions at the five magnetized planets, from the observations of Ulysses at Jupiter …
How uncertain are solar neutrino predictions?
Basu, Sarbani; Pinsonneault, M. H.; Bahcall, John N.
Solar neutrino fluxes and sound speeds are calculated using a systematic reevaluation of nuclear fusion rates. The largest uncertainties are identified and their effects on the solar neutrino fluxes are estimated.
ICCD Speckle Observations of Binary Stars. XIX. an Astrometric/Spectroscopic Survey of O Stars
Gies, Douglas R.; Bagnuolo, William G., Jr.; Mason, Brian D. +3 more
We present the results of a speckle interferometric survey made with the CHARA speckle camera and 4 m-class telescopes of Galactic O-type stars with V < 8. We can detect with the speckle camera binaries in the angular separation range 0.035" < rho < 1.5" with Deltam < 3, and we have discovered 15 binaries among 227 O-type systems. We c…