5,501 research outputs found
Some comments on the ''the composition of the Martian surface'' by R. A. Van Tassel and J. W. Salisbury
Feasibility of Martian surface layer composed of silicates coated with limonit
SEASAT B orbit synthesis
Addition were made to Battelle's Interactive Graphics Orbit Selection (IGOS) program; IGOS was exercised via telephone lines from JPL, and candidate SEASAT orbits were analyzed by Battelle. The additions to the program enable clear understanding of the implications of a specific orbit to the diverse desires of the SEASAT user community
Development of an evaluation technique for strapdown guidance systems Interim scientific report
Evaluation technique to measure performance of strapdown guidance systems designed for unmanned interplanetary mission
Upper limits on liquid water in the Venus atmosphere
Upper limits on liquid water in Venus atmosphere due to presence of hydrogen chlorid
The Influence of Topography on the Formation of Temporary Bright Patches on Mars
Influence of topography on formation of bright patches on Mar
Three undescribed pathogenic Phytophthora taxa from the south-west of Western Australia
The Phytophthora culture collection of the Vegetation Health Service of the Department of Environment and Conservation of Western Australia (WA) has been re-evaluated using DNA sequencing (Burgess et al., 2009). This has revealed many undescribed taxa previously classified as known morpho-species, one of which has recently been described as P. multivora (Scott et al., 2009).
The aim of this study was to describe three of these taxa, all of which occur in WA native ecosystems. They were compared with both the morphological species to which they are most similar and their closest phylogenetic relatives. In addition, the pathogenicity of these taxa was assessed in glasshouse trials
Linking the X-ray timing and spectral properties of the glitching AXP 1RXS J170849-400910
Previous studies of the X-ray flux and spectral properties of 1RXS
J170849-400910 showed hints of a possible correlation with the spin glitches
that occurred in 1999 and 2001. However, due to the sparseness of spectral
measurements and the paucity of detected glitches no firm conclusion could be
drawn. We retrieved and analysed archival XTE pointings of 1RXS J170849-400910
covering the time interval between January 2003 and June 2006 and carried out a
detailed timing analysis by means of phase fitting techniques. We detected two
relatively large glitches Delta nu / nu of 1.2 and 2.1 10^-6 occurred in
January and June 2005. Interestingly, the occurrence times of these glitches
are in agreement with the predictions made in our previous studies. This
finding strongly suggests a connection between the flux, spectral and timing
properties of 1RXS J170849-400910.Comment: Submitted to A&A, 4 pages; results presented at the INT meeting "The
Neutron Star Crust and Surface: Observations and Models" on June 27; referee
comments adde
VLT observations of the magnetar CXO J164710.2-455216 and the detection of a candidate infrared counterpart
We present deep observations of the field of the magnetar CXOJ164710.2-455216
in the star cluster Westerlund 1, obtained in the near-infrared with the
adaptive optics camera NACO@VLT. We detected a possible candidate counterpart
at the {\em Chandra} position of the magnetar, of magnitudes , , and . The K-band measurements available for two epochs (2006 and
2013) do not show significant signs of variability but only a marginal
indication that the flux varied (at the 2 level), consistent with the
fact that the observations were taken when CXOJ164710.2-455216 was in
quiescence. At the same time, we also present colour--magnitude and
colour--colour diagrams in the J, H, and K bands from the 2006 epoch
only, the only one with observations in all three bands, showing that the
candidate counterpart lies in the main bulk of objects describing a relatively
well--defined sequence. Therefore, based on its colours and lack of
variability, we cannot yet associate the candidate counterpart to
CXOJ164710.2-455216. Future near-infrared observations of the field,
following-up a source outburst, would be crucial to confirm the association
from the detection of near-infrared variability and colour evolution.Comment: 5 pages, 3 figures, accepted for publication in MNRA
Long term hard X-ray variability of the anomalous X-ray pulsar 1RXS J170849.0-400910 discovered with INTEGRAL
We report on a multi-band high-energy observing campaign aimed at studying
the long term spectral variability of the Anomalous X-ray Pulsar (AXP) 1RXS
J170849.0-400910, one of the magnetar candidates. We observed 1RXS
J170849.0-400910 in Fall 2006 and Spring 2007 simultaneously with Swift/XRT, in
the 0.1-10 keV energy range, and with INTEGRAL/IBIS, in the 20-200 keV energy
range. Furthermore, we also reanalyzed, using the latest calibration and
software, all the publicly available INTEGRAL data since 2002, and the soft
X-ray data starting from 1999 taken using BeppoSAX, Chandra, XMM, and
Swift/XRT, in order to study the soft and hard X-ray spectral variability of
1RXS J170849.0-400910. We find a long-term variability of the hard X-ray flux,
extending the hardness-intensity correlation proposed for this source over 2
orders of magnitude in energy.Comment: 5 pages, 2 figures, accepted for publication in Astronomy &
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