50 research outputs found
Evolution, nucleosynthesis and yields of AGB stars at different metallicities (III): intermediate mass models, revised low mass models and the ph-FRUITY interface
We present a new set of models for intermediate mass AGB stars (4.0, 5.0 and,
6.0 Msun) at different metallicities (-2.15<=Fe/H]<=+0.15). This integrates the
existing set of models for low mass AGB stars (1.3<=M/M<=3.0) already included
in the FRUITY database. We describe the physical and chemical evolution of the
computed models from the Main Sequence up to the end of the AGB phase. Due to
less efficient third dredge up episodes, models with large core masses show
modest surface enhancements. The latter is due to the fact that the interpulse
phases are short and, then, Thermal Pulses are weak. Moreover, the high
temperature at the base of the convective envelope prevents it to deeply
penetrate the radiative underlying layers. Depending on the initial stellar
mass, the heavy elements nucleosynthesis is dominated by different neutron
sources. In particular, the s-process distributions of the more massive models
are dominated by the \nean~reaction, which is efficiently activated during
Thermal Pulses. At low metallicities, our models undergo hot bottom burning and
hot third dredge up. We compare our theoretical final core masses to available
white dwarf observations. Moreover, we quantify the weight that intermediate
mass models have on the carbon stars luminosity function. Finally, we present
the upgrade of the FRUITY web interface, now also including the physical
quantities of the TP-AGB phase of all the models included in the database
(ph-FRUITY).Comment: Accepted for publication on ApJ
Dust in Supernovae and Supernova Remnants I : Formation Scenarios
Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe
Surface patterned polymer micro-cantilever arrays for sensing
Microinjection molding was employed to fabricate low-cost polymer cantilever arrays for sensor applications. Cantilevers with micrometer dimensions and aspect ratios as large as 10 were successfully
manufactured from polymers, including polypropylene and polyvinylidenfluoride. The cantilevers perform similar to the established silicon cantilevers, with Q-factors in the range of 10–20. Static deflection of gold coated polymer cantilevers was characterized with heat cycling and self-assembled monolayer formation of mercaptohexanols. A hybrid mold concept allows easy modification of the surface topography, enabling customized mechanical properties of individual cantilevers. Combined with functionalization and surface patterning, the cantilever arrays are qualified for biomedical application