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Search for brightness fluctuations in the zodiacal light at 25 MU M with ISO
Abraham, Peter; Lemke, Dietrich; Leinert, Christoph
We mapped at 25 mu m five ~0.5(deg) x0.5(deg) fields at low, intermediate and high ecliptic latitude with the photometer onboard the Infrared Space Observatory. The goal was to search for potential structures in the zodiacal light. No structures were seen in these five sample fields. For an aperture of 3' diameter we find an upper limit for the un…
Local interstellar cloud electron density from magnesium and sodium ionization: a comparison.
Ferlet, R.; Lallement, R.
The ambient interstellar plasma density (i.e. the plasma density of the interstellar medium surrounding the Sun) directly governs the structure and the size of our heliosphere. Information on this density can be derived from the ionization states of the interstellar species which can be detected in absorption along the paths to the nearby stars, a…
Detection by ISO of the far-infrared OH maser pumping lines in IRC+10420
Barlow, M. J.; Liu, X. -W.; Cox, P. +8 more
The population inversions which lead to circumstellar hydroxyl (OH) maser emission from cool stars have long been thought to be radiatively pumped. However, the proposed pumping mechanism has not been directly observed before now, because the spectral lines that correspond to the rotational transitions of the pumping cycle lie in the far-infrared,…
The neon abundance in WC stars - I. ISO SWS spectroscopy of WR146 (WC6+O)
Crowther, P. A.; Willis, A. J.; Morris, P. W. +4 more
We present infrared spectroscopy in the wavelength range 2.6-20mum of the WC6+O binary system WR146 (MR112) obtained with the Short Wavelength Spectrometer (SWS) on the Infrared Space Observatory (ISO). These data are combined with ground-based optical (INT) and near-IR (UKIRT) spectroscopy and theoretical continuum distributions revealing E(B-V) …
High-Resolution X-Ray Image of the Hydrogen-deficient Planetary Nebula Abell 30
Chu, You-Hua; Chang, Thomas H.; Conway, Gail M.
Abell 30 is the brighter of only two planetary nebulae that show extended X-ray emission. Our recent ROSAT high-resolution imager observation of A30 reveals a central source at a 4 σ level and emission knots at a 2 σ level. These emission features are within the same region as the H-deficient knots and filaments resolved in a previous HST WFPC2 [O…
The mass, temperature and distance of the white dwarf in V471 Tauri
Barstow, M. A.; Holberg, J. B.; Cruise, A. M. +1 more
We present an analysis of far-UV observations of V471 Tauri made during the first ORFEUS mission. Combining this spectrum with archival data from IUE allows a first unambiguous measurement of the effective temperature and surface gravity of the white dwarf by matching the observed Lyman line profiles to the predictions of stellar model atmosphere …
Hubble Space Telescope Observations of the Gravitationally Lensed Cloverleaf Broad Absorption Line QSO H1413+1143: Imaging
Turnshek, David A.; Rao, Sandhya M.; Espey, Brian R. +2 more
An analysis of Hubble Space Telescope (HST) Wide Field Planetary Camera (WFPC) and Wide Field Planetary Camera 2 (WFPC2) images of the gravitationally lensed Cloverleaf broad absorption line quasi-stellar object (QSO) H1413+1143 is presented. Astrometric and photometric measurements are derived for the four components of the lensed QSO for five di…
New Experimental Data and What It Tells Us About the Sources and Acceleration of Cosmic Rays
Webber, W. R.
This paper summarizes new data in several fields of astronomy that relate to the origin and acceleration of cosmic rays in our galaxy and similar nearby galaxies. Data from radio astronomy shows that SNRs, both in our Galaxy and neighboring galaxies, appear to be the sources of most of the accelerated electrons observed in these galaxies. Gamma-ra…
Venus tail ray observation near Earth
Livi, S.; Hsieh, K. C.; Wurz, P. +23 more
In June, 1996, Venus passed through a very close inferior conjunction with the Sun. At that time the CTOF detector of the CELIAS mass spectrometer experiment on the SOHO spacecraft near Earth's L1 Lagrangian point was measuring heavy ions in the solar wind ∼4.5 × 107 km downstream of Venus. Close to the time predicted by simple geometri…
Principles of statistical astrometry
Wielen, R.
We present a coherent scheme of `statistical astrometry' for high-precision measurements. Statistical astrometry provides methods and tools for treating quantitatively the overall statistical effect of the presence of many individually unresolved or unmodelled astrometric binaries in a stellar ensemble. The non-linear motions of the photo-centers …