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Chandra Observation of NGC 6822
Tennant, Allyn F.
Chandra observed the nearby dwarf galaxy NGC 6822. There are 70 sources in the Chandra field, two of which are fairly extended and likely background clusters of galaxies. A third source was resolved by Chandra that has the same size and position as a known supernova remnant. The suspected variability detected from this source in previous missions …
The Gradual Phase of the X17 Flare on October 28, 2003
Schmieder, B.; Berlicki, A.; del Zanna, G. +2 more
We present SOHO/CDS observations taken during the gradual phase of the X17 flare that occurred on October 28, 2003. The CDS data are supplemented with TRACE and ground-based observations. The spectral observations allow us to determine velocities from the Doppler shifts measured in the flare loops and in the two ribbon kernels, one hour and a half…
Temporal and Spatial Relationships between Ultraviolet and Hard X-Ray Emission in Solar Flares
Alexander, David; Coyner, Aaron J.
Hard X-ray and ultraviolet emissions in solar flares provide evidence for the interaction of particles accelerated in the solar corona with the ambient plasma in the chromosphere. Previous studies have shown that these emissions are temporally correlated indicating a common source, presumably magnetic reconnection, governing the flare energy relea…
Plasma wave source location using CLUSTER as a spherical wave telescope
Glassmeier, K. -H.; Motschmann, U.; FräNz, M. +3 more
The use of sensor arrays in space opens up the possibility to investigate the source location of plasma waves. In order to do so, we generalize the wave telescope technique to use spherical waves instead of plane waves. The new tool determines the center of the wavefronts locally measured by the sensor array. This virtual source can be related wit…
IMF Direction Derived from Cycloid-Like Ion Distributions Observed by Mars Express
Coates, A. J.; Kallio, E.; Fedorov, A. +29 more
Although the Mars Express (MEX) does not carry a magnetometer, it is in principle possible to derive the interplanetary magnetic field (IMF) orientation from the three dimensional velocity distribution of pick-up ions measured by the Ion Mass Analyser (IMA) on board MEX because pick-up ions' orbits, in velocity phase space, are expected to gyrate …
A test-particle model of the atmosphere/ionosphere system of Saturn's main rings
Tokar, R. L.; Johnson, R. E.; Young, D. T. +4 more
The first pass of the Cassini orbiter near the A and B rings of Saturn, formed mainly by H2O ice particles, revealed the presence of an ionosphere composed of O+ and O2+ ions. Such a result suggests the existence of an atmospheric halo made up of molecular oxygen surrounding the rings. It is produced by …
ISS-SOLAR: Total (TSI) and spectral (SSI) irradiance measurements
Fröhlich, C.; Thuillier, G.; Schmidtke, G.
The primary objective of the ISS-SOLAR mission on Columbus (to be launched in 2006) is the quasi-continuous measurement of the solar irradiance variability with highest possible accuracy. For this reason the total spectral range will be recorded simultaneously from 3000 to 17 nm by three sets of instruments: SOVIM is combining two types of absolut…
The Narrow-Line Region of the Seyfert 2 Galaxy Mrk 78: An Infrared View
Pérez García, A. M.; Acosta-Pulido, J. A.; Ramos Almeida, C. +3 more
We report near-infrared spectroscopic data for the Seyfert 2 galaxy Mrk 78, taken with the LIRIS near-infrared camera/spectrometer at the William Herschel Telescope (WHT). The long-slit spectra clearly show extended emission. The resolution and depth of the near-infrared spectra allow the examination of its morphology and ionization regions, and a…
Interstellar abundances in the neutral and ionized gas of NGC 604
Kunth, D.; Lebouteiller, V.; Vidal-Madjar, A. +5 more
Aims.We present FUSE spectra of the giant H ii region NGC 604 in the spiral galaxy M 33. Chemical abundances are tentatively derived from far-UV absorption lines and compared to those derived from optical emission lines.
Methods: .Absorption lines from neutral hydrogen and heavy elements were observed against the continuum provided by the youn…
XMM-Newton observation of the bright Seyfert 1 galaxy, MCG+8-11-11
de Rosa, A.; Perola, G. C.; Bianchi, S. +2 more
We report on the XMM-Newton observation of the bright Seyfert 1 galaxy, MCG+8-11-11. Data from the EPIC/p-n camera, the Reflection Gratings Spectrometers (RGS), and the Optical Monitor (OM) were analyzed. The p-n spectrum was fitted well by a power law, a spectrally unresolved Fe Kα line, a Compton reflection component (whose high value, when comp…