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Observations of Bright Coronal Points at Wavelengths of 5.2 and 1.76 cm
Maksimov, V. P.; Prosovetskii, D. V.; Krissinel, B. B.
Based on two-dimensional solar images obtained with the Siberian Solar Radio Telescope and the Nobeyama Radio Heliograph and using YOHKOH soft X-ray images, we investigate bright coronal points. The principal microwave emission mechanism of these points is shown to be the thermal bremsstrahlung of an optically thin plasma. The fact that, in severa…
Asteroids in the infrared - Serendipitous observations with ISO
Müller, T. G.
The infrared space observatory (ISO) observed many asteroids in great detail, including near-Earth asteroids (NEA). Additionally, a large number of observing programmes contain serendipitous observations of known and unknown solar system objects (SSO). The ISO specific constraints, like sensitivity, visibility and orbit parallax and their conseque…
Energetic particle measurements during the earth swing-by of the Cassini spacecraft in August 1999
Livi, S.; Krupp, N.; Woch, J. +3 more
We report on energetic particle measurements from the Low-Energy Magnetospheric Measurement System (LEMMS) aboard the Cassini spacecraft during the Earth swing-by maneuver in August 1999. LEMMS is capable of identifying the energy and incidence direction of energetic ions and electrons with energies of a few tens of keV to several tens of MeV. Cas…
Hubble Space Telescope Photometry of Clusters of Galaxies behind the Dwarf Irregular Galaxies DDO 216 and IC 1613 and the Small Magellanic Cloud
Hodge, Paul W.; Krienke, Karl
We have measured the integrated colors of galaxies in clusters located behind the dwarf irregular galaxies DDO 216 (Pegasus) and IC 1613 and a position in the Small Magellanic Cloud (SMC) near the cluster Lindsey 31. We examine limits on the accuracy of using these for studying the total extinction in galaxies. We show that the method is feasible …
Oxygen abundances derived in unevolved very metal-poor stars
Rebolo, R.; Bonifacio, P.; Molaro, P. +4 more
Oxygen abundances have been derived in a sample of very metal-poor stars from observations of the O I triplet at λλ 7771-5 Å and OH lines in the near UV. Iron abundances derived in LTE were corrected for NLTE effects following Thévenin and Idiart [ApJ 521 (1999) 753]. Furthermore, a detailed NLTE analysis of iron lines has been carried out for one…
Planetary Nebula He 2-36: Still Enigmatic, But Getting Less So
Feibelman, Walter A.; Kondo, Yoji
IUE spectra of He 2-36 indicate that the stellar C IV λ1549 doublet varies in intensity by a factor of 2.5 during a one-year interval. Detection of [Ne IV] λ2424, plus previously known He II and C IV, argue for a hot companion to the cool A2 III nucleus. The C IV emission shows a split profile that strongly resembles the profile (reprocessed in th…
Energetic Particle Fluxes during the Bastille Day Solar Eruption
Mäkelä, Pertti; Torsti, Jarmo
We report on our observations of solar energetic particle fluxes of p, He, C, O, Ne, Mg, Si, and Fe ions measured by the Energetic and Relativistic Nucleon and Electron (ERNE) experiment associated with the Bastille Day solar flare and coronal mass ejection (CME) on 14 July 2000. We observed two clear maxima of the Fe/O ratio at the energies 8.5-1…
Temporal and spatial variations of the quiet upper chromosphere from SOHO/SUMER observations of hydrogen Lyman lines
Kariyappa, R.; Curdt, W.; Varghese, B. A.
We have analyzed a time series of spectra in the hydrogen Lyman lines and the Lyman continuum obtained by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on the SOlar Heliospheric Observatory (SOHO). The time series of about 2 hours and 22 min was obtained on 1999 March 9 in a quiet region near the center of the solar …
Where Are the Absorbers toward Q2302+029?
Bowen, David V.; Jenkins, Edward B.; Pettini, Max +1 more
We present images and spectroscopy of objects close to the sight line of Q2302+029 in order to search for galaxies responsible for the remarkable z=0.7 high-ionization absorption-line system found by Jannuzi et al. This system shows ``normal'' narrow O VI, N V, and C IV lines superimposed on broader (3000-5000 km s-1 wide), unsaturated …
Variation mechanisms in symbiotic nova V1329 Cygni
Chochol, D.; Wilson, R. E.
U,B,V light curves of symbiotic nova V1329 Cygni (=HBV 475) are modelled in terms of combined wind and chromospheric fluorescence, with eclipses and shadowing of fluorescent regions, eccentric orbit effects, and conversion of far-ultraviolet energy into the optical bands. Observational evidence regarding fluorescent brightness variation mechanisms…