Bars & boxy/peanut bulges in thin & thick discs: I. Morphology and line-of-sight velocities of a fiducial model

We explore trends in the morphology and line-of-sight (los) velocity of stellar populations in the inner regions of disc galaxies, using N-body simulations with both a thin (kinematically cold) and a thick (kinematically hot) disc which form a bar and boxy/peanut (b/p) bulge. The bar in the thin disc component is $\sim$50\% stronger than the thick disc bar and is more elongated, with an axis ratio almost half that of the thick disc bar. The thin disc b/p bulge has a pronounced X-shape, while the thick disc b/p is weaker with a rather boxy shape. This leads to the signature of the b/p bulge in the thick disc to be weaker and further away from the plane than in the thin disc. Regarding the kinematics, we find that the los velocity of thick disc stars in the outer parts of the b/p bulge can be \emph{larger} than that of thin disc stars, by up to 40\% and 20\% for side-on and Milky Way-like orientations of the bar respectively. This is due to the different orbits followed by thin and thick disc stars in the bar-b/p region, which are affected by the fact that: i) thin disc stars are trapped more efficiently in the bar - b/p instability and thus lose more angular momentum than their thick disc counterparts and ii) thick disc stars have large radial excursions and therefore stars from large radii with high angular momenta can be found in the bar region. We also find that the difference between the los velocities of the thin and thick disc in the b/p bulge ($\Delta v_{los}$) correlates with the initial difference between the radial velocity dispersions of the two discs ($\Delta \sigma$) . We therefore conclude that stars in the bar - b/p bulge will have considerably different morphologies and kinematics depending on the kinematic properties of the disc population they originate from.Comment: Accepted for publication in A&A. 15 pages (2 page appendix). 16 figure

The formation of planetary disks and winds: an ultraviolet view

Planetary systems are angular momentum reservoirs generated during star formation. This accretion process produces very powerful engines able to drive the optical jets and the molecular outflows. A fraction of the engine energy is released into heating thus the temperature of the engine ranges from the 3000K of the inner disk material to the 10MK in the areas where magnetic reconnection occurs. There are important unsolved problems concerning the nature of the engine, its evolution and the impact of the engine in the chemical evolution of the inner disk. Of special relevance is the understanding of the shear layer between the stellar photosphere and the disk; this layer controls a significant fraction of the magnetic field building up and the subsequent dissipative processes ougth to be studied in the UV. This contribution focus on describing the connections between 1 Myr old suns and the Sun and the requirements for new UV instrumentation to address their evolution during this period. Two types of observations are shown to be needed: monitoring programmes and high resolution imaging down to, at least, milliarsecond scales.Comment: Accepted for publication in Astrophysics and Space Science 9 figure

Caracterización de la fenología de Fagus sylvatica L. en poblaciones mediterráneas del Sistema Central español mediante datos Landsat OLI/ETM+ y Sentinel-2A/B

[EN] The Spanish Central Range hosts some of the southernmost populations of Fagus sylvatica L. (European beech). Recent cartography indicates that these populations are expanding, going up-streams and gaining ground to oak forests of Quercus pyrenaica Willd., heather-lands, and pine plantations. Understanding the spectral phenology of European beech populations—which leaf flush occurs earlier than other vegetation formations—in this Mediterranean mountain range will provide insights of the species recent dynamics, and will enable modelling its performance under future climate oscillations. Intra-annual series of 211 Landsat OLI/ETM+ images, acquired between April 2013-December 2019, and 217 Sentinel-2A/B images, acquired between April 2017-December 2019, were employed to characterize the spectral phenology of European beech populations and five other vegetation types for comparison in an area of 108000 ha. Vegetation indices (VI) including the Normalized Difference Vegetation Index (NDVI) and Tasseled Cap Angle (TCA) from Landsat, and the NDVI and Enhanced Vegetation Index (EVI) from Sentinel-2 were retrieved from sample pixels. The temporal series of these VI were modelled with Savitzky-Golay and double logistic functions, and assessed with TIMESAT software, enabling the parametric characterization of European beech spectral phenology in the area with the start, length, and end of season, as well as peak time and value. The length of beech phenological season was similar when portrayed by Landsat and Sentinel-2 NDVI time series (214 and 211 days on average for the common period 2017-2019) although start and end differed. Compared with NDVI counterparts the TCA season started and peaked later, and the EVI season was shorter. Sentinel-2 NDVI peaked higher than Landsat NDVI. The European beech had an earlier (21 days on average) start of season than competing oak forests. Joint analysis of data from the virtual constellation Landsat/ Sentinel-2 and calibration with field observations may enable more detailed knowledge of phenological traits at the landscape scale.[ES] Algunas de las poblaciones más meridionales de Fagus sylvatica L. (haya) se encuentran en el Sistema Central español. La cartografía reciente de estas poblaciones indica que están expandiéndose a lo largo de arroyos y ganando terreno a robledales de Quercus pyrenaica Willd., brezales, y pinares. Conocer la fenología espectral de estos hayedos mediterráneos de montaña, cuya apertura de hojas se adelanta a la de otras formaciones vegetales permitiría inferir su dinámica reciente y modelizar su comportamiento frente a futuras oscilaciones climáticas. Se utilizaron 211 imágenes Landsat OLI/ETM+ adquiridas entre abril 2013-diciembre 2019 y 217 imágenes Sentinel-2A/B adquiridas entre abril 2017-diciembre 2019 para caracterizar la fenología espectral de hayedos y otras cinco formaciones vegetales en 108000 ha. Se calcularon y analizaron índices de vegetación: Normalized Difference Vegetation Index (NDVI) y Tasseled Cap Angle (TCA) con datos Landsat, NDVI y Enhanced Vegetation Index (EVI) con Sentinel-2. Se extrajeron las series temporales de estos índices en píxeles muestra para analizar mediante software TIMESAT, ajustando modelos Savitzky-Golay y función logística, y describiendo paramétricamente la fenología espectral: inicio, fin, y duración de temporada, así como momento y valor máximo del índice. Las series NDVI de Landsat y Sentinel-2 representaron una duración similar de la temporada fenológica (214 y 211 días para el periodo común de análisis, 2017-2019), aunque inicio y fin no coincidieron. Comparando con las curvas NDVI homólogas, la temporada TCA comenzó y alcanzó el pico máximo antes, y la temporada EVI fue más corta. Los valores máximos de NDVI en las series Sentinel-2 fueron más altos que los de Landsat. Los hayedos comenzaron la temporada fenológica de media 21 días antes que los robledales. El análisis conjunto de datos de la constelación virtual Landsat/Sentinel-2 y la calibración con observaciones de campo permitirá conocer mejor la fenología a escala de paisaje.This work was funded by the Spanish Ministry of Science, Innovation and University through projects: AGL2013-46028-R “Forest manage-ment facing the change in forest ecosystems dynamics: a multiscale approach (SCALyFOR)” and AGL201676769-C2-1-R “Influence of nat-ural disturbance regimes and management on forests dynamics, structure and carbon balance (FORESTCHANGE)”. Field work assistance by Diego Galán, Belén Oñate, and Gregorio Cerezo, and the support of José Juárez Benítez, director of the Sierra Norte de Guadalajara Natural Park are much appreciated.Gómez, C.; Alejandro, P.; Montes, F. (2020). Phenological characterization of Fagus sylvatica L. in Mediterranean populations of the Spanish Central Range with Landsat OLI/ETM+ and Sentinel-2A/B. Revista de Teledetección. 0(55):71-80. https://doi.org/10.4995/raet.2020.13561OJS7180055Augspurger, C.K. 2013. Reconstructing patterns of temperature, phenology, and frost damage over 124 years: Spring damage risk is increasing. Ecology 94, 41-50. https://doi.org/10.1890/12-0200.1Bolton, D.K., Gray, J.M, Melaas, E.K., Moon, M., Eklundh, L., Friedl, M.A. 2020. Continental-scale land surface phenology from harmonized Landsat 8 and Sentinel-2 imagery, Remote Sensing of Environment, 240, 111685. https://doi.org/10.1016/j.rse.2020.111685Bucha T, Koren, M. 2017. 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Flavor violating decays of the Higgs bosons in the THDM-III

We calculate the branching ratios for the decays of neutral Higgs bosons ($h^{0},H^{0},A^{0}$) into pairs of fermions, including flavor violating processes, in the context of the General Two Higgs Doublet Model III.Comment: 23 pages, 10 figures, 6 tables. Text clarifying equations and references added, typos correction