Comment on "Evidence of extensional metamorphism associated to Cretaceous rifting of the North-Maghrebian passive margin : The Tanger-Ketama Unit (external Rif, northern Morocco)" by Vázquez et al., Geologica Acta 11 (2013), 277-293

No abstrac

New UBVRI colour distributions in E-type galaxies I.The data

New colour distributions have been derived from wide field UBVRI frames for 36 northern bright elliptical galaxies and a few lenticulars. The classical linear representations of colours against log r were derived, with some improvements in the accuracy of the zero point colours and of the gradients. The radial range of signicant measurements was enlarged both towards the galaxian center and towards the outskirts of each object. Thus, the "central colours", integrated within a radius of 3", and the "outermost colours" averaged near the mu_V = 24 surface brightness, could also be obtained. Some typical deviations of colour profiles from linearity are described. Colour-colour relations of interest are presented. Very tight correlations are found between the U-V colour and the Mg2 line-index, measured either at the galaxian center or at the effective radius.Comment: 34 pages, 10 figures, to appear in A&A journa

M32+/-1

WFPC-2 images are used to study the central structure of M31, M32, and M33. The dimmer peak, P2, of the M31 double nucleus is centered on the bulge to 0.1", implying that it is the dynamical center of M31. P2 contains a compact source discovered by King et al. (1995) at 1700 A. This source is resolved, with r_{1/2} approx0.2 pc. It dominates the nucleus at 3000 A, and is consistent with late B-early A stars. This probable cluster may consist of young stars and be an older version of the cluster of hot stars at the center of the Milky Way, or it may consist of heavier stars built up from collisions in a possible cold disk of stars orbiting P2. In M32, the central cusp rises into the HST limit with gamma approx0.5, and the central density rho_0>10^7M_sol pc^-3. The V-I and U-V color profiles are flat, and there is no sign of an inner disk, dust, or any other structure. This total lack of features seems at variance with a nominal stellar collision time of 2 X 10^10 yr, which implies that a significant fraction of the light in the central pixel should come from blue stragglers. InM33, the nucleus has an extremely steep gamma=1.49 power-law profile for 0.05"<r<0.2" that becomes shallower as the HST resolution limit is approached. The profile for r<0.04" has either a gamma approx 0.8 cusp or a small core with r_c ~<0.13 pc. The central density is rho_0 > 2 10^6M_sol pc^-3, and the implied relaxation time is only ~3 X 10^6 yr, indicating that the nucleus is highly relaxed. The accompanying short collision time of 7 X 10^9 yr predicts a central blue straggler component quantitatively consistent with the strong V-I and B-R color gradients seen with HST and from the ground.Comment: 44 pages, 22 figures (7 as separate JPEG images), submitted to The Astronomical Journal. Full postscript image available at http://www.noao.edu/noao/staff/lauer/lauer_paper

Cerium anomalies in lateritic profiles

L'étude minéralogique et géochimique des terres rares permet de définir le comportement du cérium dans 4 profils latéritiques du Camerou

Ising model with memory: coarsening and persistence properties

We consider the coarsening properties of a kinetic Ising model with a memory field. The probability of a spin-flip depends on the persistence time of the spin in a state. The more a spin has been in a given state, the less the spin-flip probability is. We numerically studied the growth and persistence properties of such a system on a two dimensional square lattice. The memory introduces energy barriers which freeze the system at zero temperature. At finite temperature we can observe an apparent arrest of coarsening for low temperature and long memory length. However, since the energy barriers introduced by memory are due to local effects, there exists a timescale on which coarsening takes place as for the Ising model. Moreover the two point correlation functions of the Ising model with and without memory are the same, indicating that they belong to the same universality class.Comment: 10 pages, 7 figures; some figures and some comments adde

Evidence for tidal interaction and merger as the origin of galaxy morphology evolution in compact groups

We present the results of a morphological study based on NIR images of 25 galaxies, with different levels of nuclear activity, in 8 Compact Groups of Galaxies (CGs). We perform independently two different analysis: a isophotal study and a study of morphological asymmetries. The results yielded by the two analysis are highly consistent. For the first time, it is possible to show that deviations from pure ellipses are produced by inhomogeneous stellar mass distributions related to galaxy interactions and mergers. We find evidence of mass asymmetries in 74% of the galaxies in our sample. In 59% of these cases, the asymmetries come in pairs, and are consistent with tidal effects produced by the proximity of companion galaxies. The symmetric galaxies are generally small in size or mass, inactive, and have an early-type morphology. In 20% of the galaxies we find evidence for cannibalism. In 36% of the early-type galaxies the color gradient is positive (blue nucleus) or flat. Summing up these results, as much as 52% of the galaxies in our sample could show evidence of an on going or past mergers. Our observations suggest that galaxies in CGs merge more frequently under ``dry'' conditions. The high frequency of interacting and merging galaxies observed in our study is consistent with the bias of our sample towards CGs of type B, which represents the most active phase in the evolution of the groups. In these groups we also find a strong correlation between asymmetries and nuclear activity in early-type galaxies. This correlation allows us to identify tidal interactions and mergers as the cause of galaxy morphology transformation in CGs.[abridge]Comment: 64 pages, 35 figures. Accepted for publication in Ap

Evidence for surface uplift of the Atlas Mountains and the surrounding peripheral plateaux: Combining apatite fission-track results and geomorphic indicators in the Western Moroccan Meseta (coastal Variscan Paleozoic basement)

This work represents an initial attempt to link the evolution of the topography in relation to the general tectonic framework of western Morocco. For this purpose, in a section of the Western Moroccan Meseta different tools are combined in order to attain the general objective. Apatite fission-track (AFT) data of granitic rocks of the Rabat–Khenifra area give ages around 200 Ma with track length distributions which are compatible with the thermal models already established for the area. An inverse correlation between AFT ages and elevation is observed which is compatible with previous models indicating northward tilting of the whole Western Moroccan Meseta which is younger than 20–25 Ma. In order to test this possibility a detailed analysis of the topography at different scales in the Western Moroccan Meseta has been performed. Results indicate that two open folds with different amplitudes are recognized and that the one with wider wavelength could correspond to a lithospheric fold as previously stated by other authors on the basis of independent geological arguments. The northward tilting proposed based on the AFT data agrees with the results obtained in the analysis of the topography which reinforces the presence of a very open fold with a wavelength of 200–300 km in the north-western limb of the Western Moroccan Meseta

Far-Ultraviolet Color Gradients in Early-Type Galaxies

We discuss far-UV (1500 A) surface photometry and FUV-B color profiles for 8 E/S0 galaxies from images taken with the Ultraviolet Imaging Telescope, primarily during the Astro-2 mission. In three cases, the FUV radial profiles are more consistent with an exponential than a de Vaucouleurs function, but there is no other evidence for the presence of a disk or of young, massive stars. In all cases except M32 the FUV-B color becomes redder at larger radii. There is a wide range of internal radial FUV-B color gradients. However, we find no correlation between the FUV-B color gradients and internal metallicity gradients based on Mg absorption features. We conclude that metallicity is not the sole parameter controlling the "UV upturn component" in old populations.Comment: 11 pages; tar.gz file includes LaTeX text file, 3 PostScript figures. Paper to be published in ApJ Letter