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The NICMOS Polarimetric Calibration
Axon, D.; Batcheldor, D.; Sparks, W. +3 more
An accurate knowledge of the absolute calibration of the polarizing elements in the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) becomes especially important when conducting studies that require measuring degrees of polarization of close to 1% in the near-infrared. We present a comprehensive study of all previously observed polarime…
Estimating the Thickness of the Heliosheath from CELIAS/HSTOF and Voyager 1 Data
Hsieh, K. C.; Hilchenbach, M.; Czechowski, A. +2 more
We use recent Voyager 1 measurements of the ion fluxes beyond the termination shock and the SOHO HSTOF/CELIAS measured fluxes of the energetic neutral hydrogen and helium at 1 AU to estimate the neutral hydrogen column density NH in the heliosheath. Our best estimate is NH=1.13×1014 cm-2. The result corr…
The infrared void in the Lupus dark clouds revisited: a polarimetric approach
Franco, G. A. P.; Alves, F. O.
The results of B-band CCD imaging linear polarimetry obtained for stars from the Hipparcos catalogue are used to re-examine the distribution of the local interstellar medium towards the IRAS 100-µm emission void in the Lupus dark clouds. The analysis of the obtained parallax-polarization diagram assigns to the dark cloud Lupus1 a distance be…
New multi-fluid MHD model of comet 26P/Grigg-Skjellerup: Extrapolation to comet 67P/Churyumov-Gerasimenko
Benna, M.; Mahaffy, P. R.
The Multi-fluid MHD simulator CASIM3D models the atmosphere of comet 26P/Grigg-Skjellerup as it was seen by the Giotto spacecraft during its flyby of the comet in July 1992. CASIM3D integrates the major chemical reactions and physical interactions to compute self-consistently over an adaptive Cartesian mesh the dynamics of ions, electrons, and neu…
Subarcsecond Resolution Mid-Infrared Observations of Super Star Clusters in the Antennae (NGC 4038/4039)
Schaerer, D.; Wang, Z.; Brandl, B. R. +3 more
We present ground-based subarcsecond mid-infrared imaging and spectroscopy of young super star clusters in the overlap region of the merging galaxies NGC 4038/4039 (the Antennae) obtained with the VLT Imager and Spectrometer for mid-InfraRed (VISIR). With its unprecedented spatial resolution, VISIR begins for the first time to resolve the H II/pho…
Titan imagery with Keck adaptive optics during and after probe entry
de Pater, Imke; Brown, Michael E.; Marchis, Franck +6 more
We present adaptive optics data from the Keck telescope, taken while the Huygens probe descended through Titan's atmosphere and on the days following touchdown. No probe entry signal was detected. Our observations span a solar phase angle range from 0.05° up to 0.8°, with the Sun in the west. Contrary to expectations, the east side of Titan's stra…
The April 8, 2005, Eclipse White-Light Corona
Pasachoff, Jay M.; Rušin, Vojtech; Druckmüller, Miloslav +2 more
The hybrid solar eclipse of April 8, 2005, provided a good opportunity to observe the white-light solar corona, even though the eclipse lasted just 30 seconds and could be seen only from ships in the Pacific Ocean. During the eclipse, we detected a unique `cloud' of particles in the white-light corona above the west limb ≈260°-270°. We compare thi…
Coronal Heating and Photospheric Turbulence Parameters: Observational Aspects
Romano, P.; Abramenko, V. I.; Pevtsov, A. A.
In this study, the soft X-ray luminosity of the solar corona, measured by the Yohkoh spacecraft for 104 well-developed and decaying active regions, is compared to the magnetic field parameters determined from SOHO MDI high-resolution magnetograms. We calculate and compare (1) two area-independent characteristics of the magnetic field: the index (α…
A Spectroscopic Study of the Star-Forming Properties of the Center of NGC 4194
Kaiser, M. E.; Weistrop, D.; Nelson, C. H. +1 more
We have obtained Space Telescope Imaging Spectrograph long-slit spectra of the central region of the advanced merger NGC 4194. The spectra cover the wavelength ranges 1150-1750 Å in the UV and 2900-10270 Å in the visible. Results from the study of the properties of 14 star-forming regions (knots) are presented. If the [N II] contribution is 40% of…
The weak INTEGRAL bursts GRB 040223 and GRB 040624 : an emerging population of dark afterglows
Covino, S.; D'Avanzo, P.; Campana, S. +18 more
We report here γ-ray, X-ray and near-infrared observations of