105,032 research outputs found
Improving the 14c dating of marine shells from the Canary Islands for constructing more reliable and accurate chronologies
Radiocarbon dating of closely associated marine mollusk shells and terrestrial material (charred wood or bone) collected from archaeological contexts on Tenerife and Fuerteventura islands allowed us to quantify the marine C-14 reservoir effect (Delta R) around the Canary Archipelago. Coastal Fuerteventura has a positive weighted mean Delta R value of +185 +/- 30 C-14 yr, while for Tenerife a range of negative and positive values was obtained, resulting in a Delta R weighted mean value of 0 +/- 35 C-14 yr. These values are in accordance with the hydrodynamic system present off the Canary Islands characterized by a coastal upwelling regime that affects the eastern islands (Fuerteventura and Lanzarote) but not the other islands of the archipelago, namely Tenerife. Because of this oceanographic pattern, we recommend the extrapolation of these results to the remaining islands of the archipelago, i.e. the first value must be used for the eastern islands, while for the central and western islands the acceptable Delta R value is 0 +/- 35 C-14 yr
Limits on Hot Intracluster Gas Contributions to the Tenerife Temperature Anisotropy Map
We limit the contribution of the hot intracluster gas, by means of the
Sunyaev-Zel'dovich effect, to the temperature anisotropies measured by the
Tenerife experiment. The data is cross-correlated with maps generated from the
ACO cluster catalogue, the ROSAT PSPC catalogue of clusters of galaxies, a
catalogue of superclusters and the HEAO 1 A-1 map of X-ray sources. There is no
evidence of contamination by such sources at an rms level of K at
99% confidence level at angular resolution. We place an upper limit on
the mean Comptonization parameter of at the same
level of confidence. These limits are slightly more restrictive than those
previously found by a similar analysis on the COBE/DMR data and indicate that
most of the signal measured by Tenerife is cosmological.Comment: To be published in ApJ (main journal
The Wiener-Filtered COBE DMR Data and Predictions for the Tenerife Experiment
We apply a Wiener filter to the two-year COBE DMR data. The resulting sky map
has significantly reduced noise levels compared to the raw data: the most
prominent hot and cold spots are significant at the 4-sigma level. Furthermore,
the entire covariance matrix of the errors in the filtered sky map is known,
and it is therefore possible to make constrained realizations of the microwave
sky with the correct a posteriori probability distribution. The filtered DMR
sky map is used to make predictions for the Tenerife experiment. Two prominent
features are predicted in a region of the sky not yet analyzed by the Tenerife
group. The presence of these features is a robust prediction of the standard
cosmological paradigm; if these features are not observed, some of our
fundamental assumptions must be incorrect.Comment: 15 pages of uuencoded compressed PostScript. A PostScript file
including figures is available at ftp://pac2.berkeley.edu/pub/bunn/wienerten
Searching for a link between the presence of chemical spots on the surface of HgMn stars and their weak magnetic fields
We present the results of mapping the HgMn star AR Aur using the Doppler
Imaging technique for several elements and discuss the obtained distributions
in the framework of a magnetic field topology.Comment: 2 pages, 1 figure, to appear in Proceedings of IAU Symposium 259
"Cosmic Magnetic Fields: from Planets, to Stars and Galaxies", Tenerife,
Spain, November 3-7, 200
- âŠ