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Active spacecraft potential control for Cluster implementation and first results
Escoubet, C. P.; André, M.; Goldstein, R. +16 more
Electrostatic charging of a spacecraft modifies the distribution of electrons and ions before the particles enter the sensors mounted on the spacecraft body. The floating potential of magnetospheric satellites in sunlight very often reaches several tens of volts, making measurements of the cold (several eV) component of the ambient ions impossible…
M31 Globular Clusters in the Hubble Space Telescope Archive. I. Cluster Detection and Completeness
Huchra, John P.; Barmby, Pauline
Globular clusters at the distance of M31 have apparent angular sizes of a few arcseconds. While many M31 globular clusters have been detected and studied from ground-based images, the high spatial resolution of the Hubble Space Telescope (HST) allows much more robust detection and characterization of star cluster properties. We present the results…
The Nonstellar Infrared Continuum of Seyfert Galaxies
Simpson, Chris; Alonso-Herrero, Almudena; Quillen, Alice C. +2 more
JHKL'M (1-5 µm) imaging of a sample of Seyfert 2 galaxies is presented. We have performed an accurate estimate of the near-infrared nonstellar nuclear fluxes. We confirm that the near-infrared nuclear continuum between 1 and 2.2 µm of some Seyfert 2s is dominated by stellar emission, whereas the continuum emission at longer wavelengths…
Molecular Gas and the Modest Star Formation Efficiency in the ``Antennae'' Galaxies: Arp 244=NGC 4038/9
Gao, Yu; Lo, K. Y.; Lee, T. -H. +1 more
We report here a factor of 5.7 higher total CO flux in Arp 244 (the ``Antennae'' galaxies) than that previously accepted in the literature (thus a total molecular gas mass of 1.5×1010 Msolar), based on our fully sampled CO(1-0) observations at the NRAO 12 m telescope. Currently, much of the understanding and modeling of the s…
Warm H2 in the Galactic center region
Rodríguez-Fernández, N. J.; Martín-Pintado, J.; Fuente, A. +3 more
We present ISO observations of several H2 pure-rotational lines (from S(0) to S(5)) towards a sample of 16 molecular clouds distributed along the central ~ 500 pc of the Galaxy. We also present C18 O and {13 CO J=1->0 and J=2 -> 1 observations of these sources made with the IRAM-30 m telescope. With the CO da…
Very Long Lived Wave Patterns Detected in the Solar Surface Velocity Signal
Ulrich, Roger K.
The wavelike pattern of velocity variations in the outer layers of the Sun known as the ``torsional oscillations'' is shown to consist of long-lived inertial oscillation waves. The dominant pattern which was first identified at Mount Wilson and which has now been observed with the Michelson Doppler Imager instrument and the Global Oscillation Netw…
The Broad-Line and Narrow-Line Regions of the LINER NGC 4579
Filippenko, Alexei V.; Ho, Luis C.; Rix, Hans-Walter +2 more
We report the discovery of an extremely broad Hα emission line in the LINER nucleus of NGC 4579. From ground-based observations, the galaxy was previously known to contain a type 1 nucleus with a broad Hα line of FWHM~2300 km s-1 and FWZI~5000 km s-1. New spectra obtained with the Hubble Space Telescope (HST) and a 0.2" wide …
More about the structure of the high latitude Jovian aurorae
Prangé, Renée; Pallier, Laurent
This study is based on the determination of a 'reference' main oval for Jupiter's aurora from a series of high-resolution images taken with the Faint Object Camera on board the Hubble Space Telescope in the H 2 Lyman bands centered near 1550 Å. We have taken advantage of the visibility of the northern auroral oval over a large range of …
The Interstellar Medium of Star-forming Irregular Galaxies: The View with ISO
Dale, Daniel A.; Hunter, Deidre A.; Rubin, Robert H. +8 more
We present mid-infrared imaging and far-infrared (FIR) spectroscopy of five IBm galaxies observed by ISO as part of our larger study of the interstellar medium of galaxies. Most of the irregulars in our sample are very actively forming stars, and one is a starburst system. Thus, most are not typical Im galaxies. The mid-infrared imaging was in a b…
NICMOS Imaging of the Host Galaxies of z ~ 2-3 Radio-quiet Quasars
Heckman, Timothy M.; Calzetti, Daniela; Ridgway, Susan E. +1 more
We have made a deep NICMOS imaging study of a sample of five z~2-3 radio-quiet quasars with low absolute nuclear luminosities, and we have detected apparent host galaxies in all of these. Most of the hosts have luminosities approximately equal to present-day L*, with a range from 0.2L* to about 4L*. These host gala…