Descripción: Context. Recent observational and theoretical works have suggested that the Tully-Fisher relation might be generalised to include dispersion-dominated systems by combining the rotation and dispersion velocity in the definition of the kinematical indicator. Mergers and interactions have been pointed out as responsible of driving turbulent and disordered gas kinematics, which could generate Tully-Fisher relation outliers. Aims. We investigated the gas kinematics of galaxies by using a simulated sample that includes gas-disc-dominated as well as spheroid-dominated systems. We paid particular attention to the scatter evolution of the Tully-Fisher relation. We also determined the gas-phase velocity indicator, which traces the potential well of the galaxy better. Methods. Cosmological hydrodynamical simulations that include a multiphase model and physically motivated supernova feedback were performed to follow the evolution of galaxies as they are assembled. We analysed the gas kinematics of the surviving gas discs to estimate all velocity indicators. Results. Both the baryonic and stellar Tully-Fisher relations for gas-disc-dominated systems are tight while, as more dispersion-dominated systems are included, the scatter increases. We found a clear correlation between σ/V rot and morphology, with dispersion-dominated systems exhibiting higher values (>0.7). Mergers and interactions can affect the rotation curves directly or indirectly, inducing a scatter in the Tully-Fisher relation larger than the simulated evolution since z ~ 3. Kinematical indicators, which combine rotation velocity and dispersion velocity, can reduce the scatter in the baryonic and the stellar mass-velocity relations. In particular, s 1.0 = (V rot 2 + σ 2) 0.5 seems to be the best tracer of the circular velocity at larger radii. Our findings also show that the lowest scatter in both relations is obtained if the velocity indicators are measured at the maximum of the rotation curve. Conclusions. In agreement with previous works, we found that the gas kinematics of galaxies is significantly regulated by mergers and interactions, which play a key role in inducing gas accretion, outflows and starbursts. The joint action of these processes within a hierarchical ΛCDM Universe generates a mean simulated Tully-Fisher relation in good agreement with observations since z ~ 3 but with a scatter depending on morphology. The rotation velocity estimated at the maximum of the gas rotation curve is found to be the best proxy for the potential well regardless of morphology. ©2012 ESO.

Descripción: Triassic clastic and volcanic rocks from the Precordillera were deposited in the Cuyana rift basin filling half-graben systems. Contractional/transpressional Andean tectonics leads to the almost complete inversion of some portions of the basin which resulted in present-day isolated, structurally controlled outcrops of these Triassic rocks. In the Southern Precordillera both the degree of Neogene tectonic inversion and structural compexities are variable. At the regional scale, these variations in Andean deformation are related to first order anisotropies like the Cuyana basin borders and previous shear zones of Permian age (San Rafael orogenic phase). This paper focuses on the kinematic analysis done in the Cerro Manantial thrust sheet area (Cordón San Bartolo, central sector of the South Precordillera) where tectonic inversion was not that strong and the influence of oblique strain zones is practically null. Four sets of extensional/ transtensional faults were recognized affecting Triassic sedimentary rocks of the El Cielo Formation (Uspallata Group) at the Quebrada El Salto. Fault displacements are of decimetric to metric scale. Mesoscopic kinematic indicators (en-échèlon tensional gashes, Riedel shear fractures, sigmoidal fractures) were measured. Once Andean deformation was restored, a NNE direction for the Triassic extension was determined. Considering a northern branch of the Cuyana basin trending NNW (Az. 150°) and oblique to the direction of extension (Az. 35-40°), a sinistral strike-slip component could be inferred for this portion of the basin.

Descripción: Bracketed between 188-152 Ma, the Chon Aike Silicic Province developed in Patagonia covering an area of about 1,7 x 10 6 km 2 with volcanic products. An extensional tectonic regime that was active since at least the Jurassic-Cretaceous boundary accompanied this volcanic megaevent. Kinematic analyses focused in four selected localities (El Dorado - Monserrat, Norte de Cerro Vanguardia and El Fénix, in the Deseado region; and Lago Ghío, in the southern Patagonian Cordillera) allowed to define the main kinematic axes and to recognize two different kinematic events (a main and a secondary ones). Additionally these data certified the transtensional character of the Jurassic deformational event. When comparing directions of kinematic axes of all the selected localities, two kinematic domains: west and east could be discriminated. Whereas the eastern domain (El Dorado - Monserrat, Cerro Vanguardia north) shows ENE and NNW directions of extension for the main and the secondary kinematic events respectively, the western domain (El Fénix and Lago Ghío) indicate NE and NW directions of extension for the two events. The two kinematic events could be related or correspond to different volcanic facies. Considering the diachronism of the Chon Aike province (younger volcanic rocks westwards), the different kinematic fields could be linked to a large scale, non-coaxial deformation regime that controlled the emplacement of the Chon Aike volcanic province.

Descripción: We present 3D, gasdynamic simulations of jet/cloud collisions, with the purpose of modelling the HH 270/110 system. From the models, we obtain predictions of Hα and H2 1-0 s(1) emission line maps, which qualitatively reproduce some of the main features of the corresponding observations of HH 110. We find that the model that better reproduces the observed structures corresponds to a jet that was deflected at the surface of the cloud ∼ 1000 yr ago, but is now boring a tunnel directly into the cloud. This model removes the apparent contradiction between the jet/cloud collision model and the lack of detection of molecular emission in the crossing region of the HH 270 and HH 110 axes.

Descripción: In the Central Andes of southern Bolivia, northern Chile and north-western Argentina, a pattern of clockwise vertical axis rotations has been palaeomagnetically determined in Mesozoic and Cenozoic rocks cropping out in the Andean fore-arc and back-arc. The origin of these rotations is controversial. The scarcity of palaeomagnetic data available for the southern Central Andes, in particular for the Argentine Puna, is one of the problems that prevents the determination of the processes leading to the rotation pattern. With the aim of obtaining new palaeomagnetic data and trying to define the local or regional character of the rotations, 73 oriented samples were collected in the zones of Juncal Grande (25° 50′S - 67° 40′W) and Chorrillos (24° 12′S - 66°35'W), southern Argentine Puna. Remanent magnetizations, which indicate the existence of non-rotated and clockwise rotated localities, were isolated. It is suggested that the observed vertical axis rotations are of local character, controlled by the kinematics of the local structures.

Descripción: We present a new technique suitable for a detailed comparison between solar dynamo models and observations. The method is based on the technique of dynamo spectroscopy proposed by Hoyng & Schutgens (1995) and bi-orthogonal decomposition of solar data. This decomposition provides a representation of the mean and fluctuating components of the flows, yielding relevant information for the comparison. To illustrate the method, we use a simple kinematic dynamo model of the solar cycle. Irregularities are introduced in the evolution of the magnetic fields modeling the turbulent behavior of the solar convective region with a random perturbation on the external source for the poloidal field. After fine tuning the parameters of the model we obtain solar like solutions displaying a magnetic cycle of 22 years, with fluctuations in its period and amplitude. In addition, the model generates Maunder-like events with a time span of 60-100 years.