scholarly journals Metal Abundances of Damped Lyα Systems and the Chemical Evolution of Spiral Galaxies

1995 ◽  
Vol 164 ◽  
pp. 457-457
Author(s):  
Uta Fritze-V. Alvensleben ◽  
Klaus J. Fricke
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Spiral Galaxies ◽  
Metal Abundances ◽  
Enrichment Process

Our chemical evolution models describe in detail the enrichment process of a number of individual elements from 12C to 56Fe, including delayed SNI contributions. Variation of the characteristic timescale of star formation (SF) t∗ not only results in differences in the abundance evolution but also changes abundance ratios of elements originating from different nucleosvnthetic sites, as e.g. [C/O], [O/Fe], or [Mg/Fe].

scholarly journals Metal Abundances of Damped Lyα Systems and the Chemical Evolution of Spiral Galaxies

1995 ◽  
Vol 164 ◽  
pp. 424-424
Author(s):  
Uta Fritze-V. Alvensleben ◽  
Klaus J. Fricke
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Spiral Galaxies ◽  
Metal Abundances ◽  
Enrichment Process

Our chemical evolution models describe in detail the enrichment process of a number of individual elements from 12C to 56Fe, including delayed SNI contributions. Variation of the characteristic timescale of star formation (SF) t∗ not only results in differences in the abundance evolution but also changes abundance ratios of elements originating from different nucleosynthetic sites, as e.g. [C/O], [O/Fe], or [Mg/Fe].

scholarly journals A Comparison of Chemical Evolution between the Milky Way and M31 Galaxy

2006 ◽  
Vol 2 (S235) ◽  
pp. 313-313
Author(s):  
J. Yin ◽  
J.L. Hou ◽  
R.X. Chang ◽  
S. Boissier ◽  
N. Prantzos
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Milky Way ◽  
Local Group ◽  
Spiral Galaxies ◽  
Star Formation History ◽  
Milky Way Galaxy ◽  
Andromeda Galaxy ◽  
Formation History ◽  
Formation And Evolution

Andromeda galaxy (M31,NGC224) is the biggest spiral in the Local Group. By studying the star formation history(SFH) and chemical evolution of M31, and comparing with the Milky Way Galaxy, we are able to understand more about the formation and evolution of spiral galaxies.

scholarly journals The Extreme Outer Regions of Disk Galaxies: Star Formation and Metal Abundances

1999 ◽  
Vol 171 ◽  
pp. 196-203
Author(s):  
Annette Ferguson ◽  
Rosemary Wyse ◽  
Jay Gallagher
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Massive Star ◽  
Spiral Galaxies ◽  
Disk Galaxies ◽  
Physical Conditions ◽  
First Results ◽  
Disk Evolution ◽  
Metal Abundances ◽  
Optical Radius

AbstractThe extreme outer regions of disk galaxies, lying at or beyond the classical optical radius defined by R25, present an opportunity to study star formation and chemical evolution under unique physical conditions, possibly reminscent of those which existed during the early stages of disk evolution. We present here some of the first results from a large study to measure star formation rates and metallicities in the extreme outer limits of a sample of nearby spiral galaxies. Despite their low gas column densities, massive star formation is often observed in these outer parts, but at an azimuthally–averaged rate much lower than that seen in the inner disk. Gas-phase O/H abundances of roughly 10% solar characterize the gas at 1.5–2 R25. The implications of our results for star formation ‘laws’ and models of disk evolution are discussed.

The evolution of the oxygen radial gradients in spiral galaxies

2018 ◽  
Vol 14 (A30) ◽  
pp. 265-265
Author(s):  
M. Mollá ◽  
O. Cavichia ◽  
B. Gibson ◽  
P. Tissera ◽  
P. Sánchez-Blázquez ◽  
...  
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Spiral Galaxies ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Radial Gradient

AbstractWe analyse the evolution with redshift of the radial gradient of oxygen abundances in spiral disks resulting from our MULCHEM chemical evolution models, computed for galaxies of different sizes or masses, studying the relationships between the gradients and galaxy characteristics as the stellar mass, the size, the gas fraction or the star formation rate for z < 4.

scholarly journals Abundance Gradients and Chemical Evolution of Spiral Galaxies

2009 ◽  
Vol 5 (S265) ◽  
pp. 247-248
Author(s):  
Monica M. Marcon-Uchida ◽  
Francesca Matteucci ◽  
Roberto D. D. Costa
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Spiral Galaxies ◽  
Galactic Disk ◽  
Formation Rate ◽  
Group Model ◽  
Chemical Abundances ◽  
Modified Model ◽  
Formation Efficiency ◽  
Inside Out

AbstractThe distribution of chemical abundances and their variation in space and time are important tools to understand the chemical evolution of disks in spiral galaxies. In this work we present an one infall chemical evolution model for the Galactic disk based on an updated version of the Trieste group model. We adopted a pre enriched gas (to take into account the effect of the halo evolution), an inside-out scenario for the formation of the disk and a threshold in the surface gas density to regulate the star formation rate. The observational constraints for the solar neighbourhood were well reproduced and the spatial and time evolution of the radial abundance gradient were studied. We also used this model to reproduce the chemical evolution of some nearby spiral galaxies. The model was scaled to the disk properties of each galaxy and its dependence with the star formation efficiency and the time scale for the infalling gas into the disk were explored. Using this modified model we were able to reproduce the observed constraints available in the literature for this galaxies. The similarities and the differences between the chemical evolution of these objects and teh Milky Way are discussed to provide a basis to the understanding of the chemical evolution of disks.

scholarly journals CHANG-ES

2018 ◽  
Vol 611 ◽  
pp. A72 ◽  
Author(s):  
Marita Krause ◽  
Judith Irwin ◽  
Theresa Wiegert ◽  
Arpad Miskolczi ◽  
Ancor Damas-Segovia ◽  
...  
Keyword(s):  
Star Formation ◽  
Wind Velocity ◽  
Surface Density ◽  
Spiral Galaxies ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Cosmic Ray ◽  
Scale Height ◽  
Radio Continuum ◽  
Frequency Bands

Aim. The vertical halo scale height is a crucial parameter to understand the transport of cosmic-ray electrons (CRE) and their energy loss mechanisms in spiral galaxies. Until now, the radio scale height could only be determined for a few edge-on galaxies because of missing sensitivity at high resolution.Methods. We developed a sophisticated method for the scale height determination of edge-on galaxies. With this we determined the scale heights and radial scale lengths for a sample of 13 galaxies from the CHANG-ES radio continuum survey in two frequency bands.Results. The sample average values for the radio scale heights of the halo are 1.1 ± 0.3 kpc in C-band and 1.4 ± 0.7 kpc in L-band. From the frequency dependence analysis of the halo scale heights we found that the wind velocities (estimated using the adiabatic loss time) are above the escape velocity. We found that the halo scale heights increase linearly with the radio diameters. In order to exclude the diameter dependence, we defined a normalized scale height h˜ which is quite similar for all sample galaxies at both frequency bands and does not depend on the star formation rate or the magnetic field strength. However, h˜ shows a tight anticorrelation with the mass surface density.Conclusions. The sample galaxies with smaller scale lengths are more spherical in the radio emission, while those with larger scale lengths are flatter. The radio scale height depends mainly on the radio diameter of the galaxy. The sample galaxies are consistent with an escape-dominated radio halo with convective cosmic ray propagation, indicating that galactic winds are a widespread phenomenon in spiral galaxies. While a higher star formation rate or star formation surface density does not lead to a higher wind velocity, we found for the first time observational evidence of a gravitational deceleration of CRE outflow, e.g. a lowering of the wind velocity from the galactic disk.

scholarly journals Clumpy Galaxies in the Early Universe

2006 ◽  
Vol 2 (S235) ◽  
pp. 376-380 ◽  
Author(s):  
Debra Meloy Elmegreen
Keyword(s):  
Star Formation ◽  
Early Universe ◽  
Spiral Galaxies ◽  
Star Forming ◽  
Wide Range ◽  
Thick Disks ◽  
Hubble Ultra Deep Field

AbstractClumpy galaxies are prominent in the early Universe. We present morphological and photometric properties of a wide range of galaxy types and their star-forming clumps in the Hubble Ultra Deep Field. Sizes, scale lengths, and scale heights suggest that galaxies grow by a factor of 2 fromz= 4 to the present, and that thick disks are present in the early Universe. The largest clumps of star formation are 107–109M⊙in different galaxies, much more massive than large star-forming complexes in local galaxies. Dissolved clumps may account for both the exponential disks and the early thick disks of spirals and proto-spiral galaxies.

scholarly journals Bar rejuvenation in S0 galaxies?

2020 ◽  
Vol 495 (4) ◽  
pp. 4548-4556
Author(s):  
Sudhanshu Barway ◽  
Kanak Saha
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Theoretical Studies ◽  
Tidal Interactions ◽  
Colour Measurements ◽  
Induce Star Formation ◽  
Minor Mergers ◽  
Stellar Masses ◽  
S0 Galaxies ◽  
Intermediate Density

ABSTRACT Based on the colour measurements from a multiband, multicomponent 2D decompositions of S0 and spiral galaxies using SDSS images, we found that bars are bluer in S0 galaxies compared to the spiral galaxies. Most of the S0s in our sample have stellar masses ∼L* galaxies. The environment might have played an important role as most of the S0s with bluer bars are in the intermediate-density environment. The possibility of minor mergers and tidal interactions that occurs frequently in the intermediate-density environment might have caused either a bar to form and/or induce star formation in the barred region of S0 galaxies. The underlying discs show the usual behaviour being redder in S0s compared to spiral galaxies while the bulges are red and old for both S0 and spiral galaxies. The finding of bluer bars in S0 galaxies is a puzzling issue and poses an interesting question at numerical and theoretical studies most of which shows that the bars are long-lived structures with old stellar populations.

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