Interactions and star formation activity in Wolf-Rayet galaxies

We present the main results of the PhD Thesis carried out by L\'opez-S\'anchez (2006), in which a detailed morphological, photometrical and spectroscopical analysis of a sample of 20 Wolf-Rayet (WR) galaxies was realized. The main aims are the study of the star formation and O and WR stellar populations in these galaxies and the role that interactions between low surface companion objects have in the triggering of the bursts. We analyze the morphology, stellar populations, physical conditions, chemical abundances and kinematics of the ionized gas, as well as the star-formation activity of each system.Comment: 16 pages, 15 figure

Ultrafaint [C II] emission in a redshift = 2 gravitationally lensed metal-poor dwarf galaxy

Galaxie

Galaxy Metallicities, Masses and Outflows at Redshifts 1 ≲

I review the most widely used methods of determining chemical abundances in galaxies at 1≲ z ≲ 3, including emission and absorption line techniques (including a brief discussion of Damped Lyman Alpha systems). Most star-forming galaxies at these redshifts show significant enrichment, with ~1/3 solar to ~solar metallicities. They are overluminous for their metallicities compared to local galaxies, and the mass-metallicity relation at z ~ 2 is offset to lower metallicities compared to the local relation. Metals are also seen in the IGM at these redshifts, most likely from galactic-scale outflows in the galaxies themselves

Charge-state distributions of 100, 175, 275, and 352 MeV gold ions emerging from thin carbon foils

These measurements were undertaken as a consequence of our failure early this year to accelerate Au/sup +46/ ions in the Oak Ridge Isochronous Cyclotron using an injected beam of 352 MeV /sup 197/Au/sup +17/ from the 25 MV tandem accelerator. Following that unsuccessful test, we made a preliminary measurement of the charge-state distribution of 352 MeV /sup 197/Au ions emerging from a carbon foil using the bending magnet that is a part of the cyclotron beam injection system. The measured mean charge was approx.38.5, about 4.5 charge-states lower than predicted by the Sayer semi-empirical formula. The measurements reported here were done more precisely and systematically confirm that preliminary result. 12 refs., 5 figs., 4 tabs

Herschel protocluster survey: a search for dusty star-forming galaxies in protoclusters at z = 2–3

We present a Herschel/SPIRE survey of three protoclusters at z = 2 − 3 (2QZCluster, HS1700, SSA22). Based on the SPIRE colours (S350/S250 and S500/S350) of 250 μm sources, we selected high redshift dusty star-forming galaxies potentially associated with the protoclusters. In the 2QZCluster field, we found a 4σ overdensity of six SPIRE sources around 4.5′ (∼ 2.2 Mpc) from a density peak of Hα emitters at z = 2.2. In the HS1700 field, we found a 5σ overdensity of eight SPIRE sources around 2.1′ (∼ 1.0 Mpc) from a density peak of LBGs at z = 2.3. We did not find any significant overdensities in SSA22 field, but we found three 500 μm sources are concentrated 3′ (∼1.4 Mpc) east to the LAEs overdensity. If all the SPIRE sources in these three overdensities are associated with protoclusters, the inferred star-formation rate densities are 103 − 104 times higher than the average value at the same redshifts. This suggests that dusty star-formation activity could be very strongly enhanced in z ∼ 2 − 3 protoclusters. Further observations are needed to confirm the redshifts of the SPIRE sources and to investigate what processes enhance the dusty star-formation activity in z ∼ 2 − 3 protoclusters

Reduction of magnetite to metallic iron in strong alkaline medium

This work focuses on assessing the feasibility of cathodic iron extraction from the magnetite based precursors. For this, electrochemical processes at Fe3O4/alkaline electrolyte interface were screened by cycling voltammetry. Based on these results, one obtained guidelines for selecting the conditions (i.e., potential and temperature) where efficient direct electrochemical reduction of magnetite ceramics to metallic iron occurs. Electrochemical conversion of relatively dense magnetite samples yields a polycrystalline Fe scale, formed at the surface of the magnetite pellet in direct contact with the bulk electrolyte. Still, the onset of slightly open porosity results in formation of intermediate layers with coexisting magnetite and metallic Fe; this is ascribed to gradual development of additional porosity, which promotes sample impregnation with the electrolyte, extends the effective electrochemically active area, and facilitates dissolution of soluble species in the inner pores. This is clearly demonstrated by transient response behavior, with remarkable increase in the current density. The key roles of porosity and effective Fe3O4/electrolyte area are also emphasized by the enhanced kinetics of electrochemical reduction observed for highly porous magnetite samples, with nearly homogeneous distribution of reactant (Fe3O4) and product (metallic Fe), without a clear surface scale of metallic iron. In this case, the final product is very porous and fragile. The conversion of highly porous magnetite samples also proceeds with much higher Faradaic efficiency compared to nearly dense ceramics. (C) 2016 Elsevier Ltd. All rights reserved

Эволюция отношений между парламентом и президентом в Польше в период трансформации

We simulate the formation and evolution of galaxies with a self-consistent 3D hydrodynamical model including star formation, supernova feedback, and chemical enrichment. Hypernova feedback plays an essential role not only in solving the [Zn/Fe] problem, but also reproducing the cosmic star formation rate history and the mass-metallicity relations. In the Milky-Way type galaxy, the star formation history, and thus the kinematics and chemical abundances are different in bulge, disk, and thick disk

CLASSY. II.: A technical overview of the COS legacy archive spectroscopic survey

Galaxie

CLASSY. II.: A technical overview of the COS legacy archive spectroscopic survey

Galaxie