Search Publications
ZEN2: a narrow J-band search for z ~ 9 Lyα emitting galaxies directed towards three lensing clusters
Kneib, J. -P.; Minniti, D.; Courbin, F. +1 more
We present the results of a continuing survey to detect Lyα emitting galaxies at redshifts z ~ 9: the `z equals nine' (ZEN) survey. We have obtained deep VLT Infrared Spectrometer and Array Camera observations in the narrow J-band filter NB119 directed towards three massive lensing clusters: Abell clusters 1689, 1835 and 114. The foreground cluste…
Venus Express observations of atmospheric oxygen escape during the passage of several coronal mass ejections
Fedorov, A.; Barabash, S.; Futaana, Y. +7 more
The solar wind interaction contributes to the loss of Venus atmospheric constituents, especially oxygen, by direct antisunward acceleration of planetary ions and possibly by related sputtering of neutrals. Both comet-like ``ion pickup'' and related sputtering processes may have played a key role in Venus' atmosphere evolution, but the significance…
Magnetic Flux Loss and Flux Transport in a Decaying Active Region
Kubo, M.; Lites, B. W.; Ichimoto, K. +1 more
We estimate the temporal change of magnetic flux normal to the solar surface in a decaying active region by using a time series of the spatial distribution of vector magnetic fields in the photosphere. The vector magnetic fields are derived from full spectropolarimetric measurements with the Solar Optical Telescope aboard Hinode. We compare a magn…
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…