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Small-Scale Behavior of the Physical Conditions and the Abundance Discrepancy in the Orion Nebula
Mesa-Delgado, Adal; Esteban, César; García-Rojas, Jorge
We present the results of long-slit spectroscopy, in several positions, of the Orion Nebula. Our goal is to study the spatial distributions of a large number of nebular quantities, including line fluxes, physical conditions, and ionic abundances, at a spatial resolution of about 1''. In particular, we have compared the O++ abundance det…
Tyrrhena Patera: Geologic history derived from Mars Express High Resolution Stereo Camera
Greeley, Ronald; Williams, David A.; Neukum, Gerhard +4 more
We used Mars Express High Resolution Stereo Camera images of the Tyrrhena Patera volcano to assign cratering model ages to material units defined in the Viking Orbiter-based geologic mapping. Cratering model ages are generally consistent with their stratigraphy. We can identify three key intervals of major activity at Tyrrhena Patera: (1) formatio…
On the absorption of X-ray bright broad absorption line quasars
Cappi, M.; Vignali, C.; Giustini, M.
Context: Most X-ray studies of broad absorption line quasars (BALQSOs) found significant (NH∼ 1022-24 cm-2) intrinsic column densities of gas absorbing an underlying typical power-law continuum emission, in agreement with expectations from radiatively driven accretion disk wind models. However, direct spectral anal…
First upstream proton cyclotron wave observations at Venus
Russell, C. T.; Wei, H. Y.; Zhang, T. L. +3 more
The escape of particles from planetary atmospheres, especially hydrogen, is an important key towards understanding the atmospheric composition and evolution over the lifetime of the solar system. For an unmagnetized planet such as Venus or Mars when the neutral exosphere extends into the flowing solar wind plasma, loss of pick-up ions upstream of …
Probing the Nature of the Vela X Cocoon
Slane, Patrick O.; LaMassa, Stephanie M.; de Jager, Okkie C.
Vela X is a pulsar wind nebula (PWN) associated with the active pulsar B0833-45 and contained within the Vela supernova remnant (SNR). A collimated X-ray filament ("cocoon") extends south-southwest from the pulsar to the center of Vela X. VLA observations uncovered radio emission coincident with the eastern edge of the cocoon, and H.E.S.S. has det…
Discovery of heavily-obscured AGN among seven INTEGRAL hard X-ray sources observed by Chandra
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +4 more
Aims: We identify hard X-ray sources discovered by the INTEGRAL all-sky survey. We complete identification of a unique sample of active galactic nuclei (AGN) selected in the hard X-ray band (17-60 keV) with minimal effects from absorption. Subsequently, we determine the fraction of obscured AGN in the local Universe.
Methods: We observed 7 INT…
Periodic tilting of Saturn's plasma sheet
Krimigis, S. M.; Mitchell, D. G.; Roelof, E. C. +2 more
From the vantage of the dawn sector, the INCA instrument on Cassini imaged neutral hydrogen atoms (20-50 keV) emitted from the center of the Saturn's plasma sheet for five days during late 2004. Points along the center of the plasma sheet were found from contoured images projected onto the noon-midnight plane; points within 20 RS of Sat…
SMART-OLEV—An orbital life extension vehicle for servicing commercial spacecrafts in GEO
Kaiser, Clemens; Sjöberg, Fredrik; Delcura, Juan Manuel +1 more
Orbital Satellite Services Limited (OSSL) is a satellite servicing company that is developing an orbit life extension vehicle (OLEV) to extend the operational lifetime of geostationary satellites. The industrial consortium of SSC (Sweden), Kayser-Threde (Germany) and Sener (Spain) is in charge to develop and industrialize the space and ground segm…
Observations of an active thin current sheet
Dandouras, I.; Lucek, E.; Fazakerley, A. N. +11 more
We analyze observations of magnetotail current sheet dynamics during a substorm between 2330 and 2400 UT on 28 August 2005 when Cluster was in the plasma sheet at [-17.2, -4.49, 0.03] RE (GSM) with the foot points near the IMAGE ground-based network. Observations from the Cluster spacecraft, ground-based magnetometers, and the IMAGE sat…
A Broadband Microwave Burst Produced by Electron Beams
Melnikov, V. F.; Fleishman, G. D.; Huang, G. -L. +1 more
The theoretical and experimental study of fast electron beams attracts much attention in astrophysics and the laboratory. In the case of solar flares, the problem of reliable beam detection and diagnostics is of exceptional importance. This paper explores the fact that electron beams moving obliquely to the magnetic field or along the field with s…