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Spectroscopy of Massive Stars in NGC 6822 and M33
Bianchi, Luciana; Hutchings, John B.; Scuderi, Salvatore +1 more
We present blue spectra of massive stars in the Local Group galaxies NGC 6822 and M33. For all the targets, selected from our previous Hubble Space Telescope WFPC2 photometry, no previous spectroscopic studies exist, to our knowledge, except for a bright Wolf-Rayet star in NGC 6822. Photospheric parameters Teff and gravity are derived b…
On the relation between the IR continuum and the active galactic nucleus in Seyfert galaxies
Prieto, M. A.; Pérez García, A. M.; Rodríguez Espinosa, J. M.
A sample of the brightest known Seyfert galaxies from the CfA sample is analyzed on the basis of ISO photometric and spectroscopic data. Regardless of the Seyfert type, the mid-IR continuum emission from these galaxies is found to be correlated with the coronal line emission arising in the nuclear active region. Conversely, the correlation degrade…
Solar Large-Scale Emitting Chains: Evidence of Reality and Some Properties
Chertok, I. M.
A phenomenon of large-scale solar activity - relatively weak extended emitting chains with a characteristic length comparable with the solar disk radius or even diameter - were detected recently on the modified heliograms in the microwave (Nobeyama radioheliograph), soft X-ray (Yohkoh/SXT), EUV (SOHO/EIT, TRACE), and some other ranges. In this pap…
CCD astrometry of faint compact extragalactic radio sources. II.
Costa, E.
Optical positions relative to the Hipparcos Catalogue (ESA \cite{ESA97}) have been obtained for the optical counterparts of 28 faint (B ~ 20-23) southern compact extragalactic radio sources (CERS). Most of these sources are not adequately observable (or simply not visible) by means of direct photography with a conventional wide-field telescope, so…
Latitudinal Variation of the Underlying Heliospheric Magnetic Field Direction: Comparison of the Ulysses First and Second Orbits
Balogh, A.; Forsyth, R. J.; Smith, E. J.
We discuss the underlying direction of the heliospheric magnetic field measured by Ulysses in the latitude range 6° S-65° S by examining distributions of the magnetic field azimuthal angle with respect to the simple Parker spiral model. During the first Ulysses traversal of this latitude range in 1992 1994, while solar activity was declining, the …
ISOCAM 3-12 µm imaging of five galactic compact HII regions.
Zavagno, A.; Ducci, V.
We present 3-12 µm ISOCAM observations of the five Galactic compact H II regions Sh 61, Sh 138, Sh 152, Sh 156 and Sh 186. The unidentified infrared bands (UIBs) centred at 3.3, 6.2, 7.7, 8.6 and 11.2 µm -and underlying continuum -are imaged using the SW1, SW2, LW4, LW6 and LW8 filters. Images are also obtained at 5.985, 6.911, 8.222, …
The Cosmic Ray Radial and Latitudinal Intensity Gradients in the Inner and Outer Heliosphere 1996-2001.3
Kunow, H.; Muller-Mellin, R.; Wibberenz, G. +7 more
The spatial intensity gradients of 150-380 MeV/n galactic cosmic ray He and 30-60 MeV/n H and He are studied over the 1996-2001.3 time period using data from the Goddard MED experiment on IMP 8, the COSPIN/KET telescope on Ulysses and the CRS experiment on Voyagers 1 and 2. This combination provides information on the radial intensity gradients in…
The warm circumstellar envelope and wind of the G9 IIb star HR 6902
Reimers, D.; Baade, R.; Kirsch, T.
IUE observations of the eclipsing binary system HR 6902 obtained at various epochs spread over four years indicate the presence of warm circumstellar material enveloping the G9 IIb primary. The spectra show Si Iv and C Iv absorption up to a distance of 3.3 giant radii (Rg). Line ratio diagnostics yields an electron temperature of ~ 78 0…
ULYSSES COSPIN observations of the energy and charge dependence of the propagation of solar energetic particles to the Sun's south polar regions
Kunow, H.; Heber, B.; McKibben, R. B. +12 more
We present a first report of energetic charged particle observations at latitudes above 70° S from the COSPIN instruments on Ulysses during Ulysses' recently completed pass over the Sun's south polar regions. Solar energetic particles dominated the particle flux during most of the pass, and for > 30 MeV protons there was a close correspondence …
Scales of heliospheric current sheet coherence between 1 and 5 AU
Crooker, N. U.; Smith, E. J.; De Keyser, J. +4 more
The structure of the heliospheric current sheet (HCS) at Ulysses and at Wind is compared during the period of near-radial alignment in 1998. Electron heat flux and magnetic field data are used to determine true magnetic field polarity. During the solar rotation period surrounding alignment there was considerable disagreement between the HCS crossi…