Outflows from evolved stars with OASIS, NAOMI and GLAS

I discuss the potential of integral-field spectroscopy (IFS) with adaptive optics in the study of the outflows from evolved stars of different masses.With IFS, detailed 3-D spatio-kinematical models of the outflows can be built, providing excellent observational datasets to be confronted with the existing dynamical theories. In addition, if multi-epoch observations are able to resolve the apparent expansion of the nebulae in the plane of the sky, then their dynamics can be further constrained, and other basic quantities like the distance via the expansion parallax, can be determined. The kind of results that can be obtained are illustrated by recent HST and VLT observations of the ring nebula around the symbiotic nova He 2-147.Given the present capabilities of the OASIS integral-field spectrograph of the Isaac Newton Group of Telescopes (ING), classical novae ejecta are the most appealing targets for such kind of studies, provided that its AO system NAOMI is complemented with the forthcoming laser guide star system GLAS.IFS+AO is also a powerful technique to detect faint ionized nebulae around bright stars, like for instance the outflows from luminous blue variables.     

Kilohertz quasi-periodic oscillations difference frequency exceeds inferred spin frequency in 4U 1636−53

We report the first detection of a sharp spectral feature in a narrow-line Seyfert 1 galaxy. Using XMM-Newton we have observed 1H     and find a drop in flux by a factor of more than 2 at a rest-frame energy of ∼ 7 keV without any detectable narrow Fe K α line emission. The energy of this feature suggests a connection with the neutral iron K photoelectric edge, but the lack of any obvious absorption in the spectrum at lower energies makes the interpretation challenging. We explore two alternative explanations for this unusual spectral feature: (i) partial-covering absorption by clouds of neutral material; and (ii) ionized disc reflection with lines and edges from different ionization stages of iron blurred together by relativistic effects. We note that both models require an iron overabundance to explain the depth of the feature. The X-ray light curve shows strong and rapid variability, changing by a factor of 4 during the observation. The source displays modest spectral variability which is uncorrelated with flux.     

New evidence for a volcanically, tectonically, and climatically active Mars

Geological analysis of Mars imagery supports the hypothesis that the planet has been the site of recent (<?10 Ma) volcanic and tectonic processes and glacier flow, and makes most likely previous suggestions of continuing endogenic and exogenic activity. Tectonic structures which deform very slightly cratered (at MOC scales) surfaces of Tharsis Montes and surrounding regions seem to attest to active tectonism (both extensional and transcurrent) on Mars. Exogenic processes in this region, such as a glacial origin for the aureole deposits on the northwestern flanks of the Tharsis Montes shield volcanoes, are supported by new data. The very recent age of these structures could be the first direct confirmation that drastic changes in obliquity are modulating the martian climate, such that an increase in obliquity would result in equatorial glaciers taking the place of the receding polar ice caps. If this and other concurring research is extended and confirmed, the ‘alive Mars’ which would emerge would constitute a most appealing place for exobiology and comparative planetology.     

Iberian Plio‐Pleistocene biochronology: micromammalian evidence for MNs and ELMAs calibration in southwestern Europe

A multivariate biochronological analysis of the Plio‐Pleistocene Iberian rodent fossil record is presented. Among more than 300 fossil sites, 49 sites have been selected. The ordination of the fossil sites selected from the Iberian Peninsula has been achieved by the appearance event ordination method. After calibration of this ordination with geochronological dates at some of the localities, numerical dates are proposed for all the localities studied. Hence, mammal fossil sites non‐datable by other means (palaeomagnetism, radiometric dating, etc.) have been dated with a relatively high degree of confidence. Final results allow dating of boundaries between the Plio‐Pleistocene European Land Mammal Ages (ELMAS) or the Mammal Neogene (MN) units. These boundaries agree with previous studies using magnetostratigraphical calibration of these scales. Copyright © 2004 John Wiley & Sons, Ltd.     

Estimation of tree water stress from stem and soil water monitoring with time‐domain reflectometry in two small forested basins in Spain

Soil‐tree water relationships were studied using time domain reflectometry (TDR) in two small forested basins in Spain. The stem water content of two Mediterranean Quercus species (Quercus pyrenaica and Quercus rotundifolia) was measured using previously constructed species‐specific equations. To monitor soil moisture, a TDR station network was used in both cases. Sixteen Q. pyrenaica and six Q. rotundifolia individuals were selected to install two TDR probes in their trunks (at 20 and 120 cm above the ground) to monitor stem water content. Stem and soil water contents were measured fortnightly. The stem water content of both species showed a similar temporal trend for the period studied. A spring maximum (0·654 cm³ cm^?3 for Q. pyrenaica and 0·568 cm³ cm^?3 for Q. rotundifolia) was found to be associated with high transpiration and no soil moisture deficit, and a late‐summer minimum (0·520 cm³ cm^?3 for Q. pyrenaica and 0·426 cm³ cm^?3 for Q. rotundifolia) was associated with the end of the dry season. This drop in stem water content occurs when the available water in the soil decreases. This seasonal difference presumably reflects water withdrawn from stem storage to support the transpirational demands of the tree. Since plant water stress results in reduced stem water content and since this drop can be measured by TDR, it may be concluded that this technology offers a suitable tool for detecting plant water stress. Copyright © 2007 John Wiley & Sons, Ltd.     

Integration of LiDAR data for the assessment of activity in diachronic landslides: a case study in the Betic Cordillera (Spain)

In the procedures to minimize diachronic landslides, data on their temporal evolution and destructive capacities are necessary. For that purpose, remote-detection techniques proved to be highly useful for quantifying the ongoing change in the relief, as well as in comparisons between digital terrain models achieved by Light Detection and Ranging. The methodology presented in this paper includes the supervised merging and comparison of sequential scans, acquired within nearly annual intervals from an irregular terrain, which improves the quality of the results highlighting ground changes. This approach is based on the processing of digital terrain models from point clouds acquired by Terrestrial Laser Scanning to quantify and interpret the landslide displacements. In parallel, it is supported by Global Navigation Satellite Systems, the use of artificial targets and a refined data processing to minimize the uncertainty and improve the precision of the results. This is applied to a large translational slide affecting phyllite rocks in a IV-V degree of weathering settled on the southern slope of Sierra Nevada (south-eastern Spain). During the monitoring period (2008–2010), the slide remained inactive until 2009, followed by a reactivation with displacements in the range ?1.80 to 1.20 m along the period 2009–2010, where negative values are downwards from the reference model (2009). The accumulated relative standard deviation between data sets was on the order of 7.5 cm, whereas the threshold to determine a terrain displacement (also avoiding changes due to erosion-accumulation processes) was of 10 cm. When applying this methodology to Airborne Laser Scanning datasets for the years 2008 and 2010, covering zones hidden to the line of sight of the terrestrial technique, a reactivation with similar deformation pattern was found useful to validate the findings, although the detail of changes and quantitative results did not match exactly due to the different accuracy and resolution of both techniques. The reactivation of the slide coincided with a period of intense rains, pointing to this as the triggering factor, with a precipitation threshold of roughly 1000 mm in a period of 4 months, only reached on one occasion throughout in the historical record.