Chemical Evolution Of The Galaxy

Rana, N. C.

doi:10.1146/annurev.astro.29.1.129

Cited by 73 publications

(138 citation statements)

References 0 publications

Supporting

Mentioning

121

Contrasting

Order By: Relevance

“…In order to reproduce the observed metallicity distribution of long-living stars in the solar neighborhood (G-dwarf problem, Pagel 1989;Rana 1991, and references therein), the simple closed-box model is proved to be unreasonable and the infall of gas from its halo has been introduced in the chemical evolution model (Tinsley 1980). Indeed, Mathewson et al (1975) conclude that a long "Hi tail" extends about 2 • to the southeast of the disk Fig.…”

Section: Gas Infall Ratementioning

confidence: 99%

The star formation history of low-mass disk galaxies: A case study of NGC 300

Kang

Zhang

Chang

et al. 2015

A&A

View full text Add to dashboard Cite

Context. Since NGC 300 is a bulgeless, isolated low-mass galaxy and it has not experienced radial migration during its evolution history, it can be treated as an ideal laboratory to test the simple galactic chemical evolution model. Aims. Our main aim is to investigate the main properties of the star formation history (SFH) of NGC 300 and compare its SFH with that of M 33 to explore the common properties and differences between these two nearby low-mass systems. Methods. We construct a simple chemical evolution model for NGC 300, assuming its disk forms gradually from continuous accretion of primordial gas and including the gas-outflow process. The model allows us to build a bridge between the SFH and observed data of NGC 300, in particular, the present-day radial profiles and global observed properties (e.g., cold gas mass, star formation rate, and metallicity). By means of comparing the model predictions with the corresponding observations, we adopt the classical χ 2 methodology to find out the best combination of free parameters a, b, and b out . Results. Our results show that by assuming an inside-out formation scenario and an appropriate outflow rate, our model reproduces well most of the present-day observational values. The model not only reproduces well the radial profiles, but also the global observational data for the NGC 300 disk. Our results suggest that NGC 300 may experience a rapid growth of its disk. Through comparing the best-fitting, model-predicted SFH of NGC 300 with that of M 33, we find that the mean stellar age of NGC 300 is older than that of M 33 and there is a recent lack of primordial gas infall onto the disk of NGC 300. Our results also imply that the local environment may play a key role in the secular evolution of galaxy disks.

show abstract

Section: Gas Infall Ratementioning

confidence: 99%

The star formation history of low-mass disk galaxies: A case study of NGC 300

Kang

Zhang

Chang

et al. 2015

A&A

View full text Add to dashboard Cite

show abstract

“…Following Bowen et al (2005), we can estimate the SFR from C * by using the Milky Way (MW) as a reference times lower than the MW value; Rémy et al, in prep.). We assume Σ SFR (MW) ≈ 4 × 10 −3 M yr −1 kpc −2 (Rana 1991) and L(MW) ≈ 2 × 10 −26 erg s −1 (H) −1 (Lehner et al 2004), and…”

Section: Cooling Rate and Sfrmentioning

confidence: 99%

Chemical enrichment and physical conditions in I Zw 18

Lebouteiller

Heap

Hubený

et al. 2013

A&A

View full text Add to dashboard Cite

Context. Low-metallicity star-forming dwarf galaxies are prime targets to understand the chemical enrichment of the interstellar medium. The H  region contains the bulk of the mass in blue compact dwarfs, and it provides important constraints on the dispersal and mixing of heavy elements released by successive star-formation episodes. The metallicity of the H  region is also a critical parameter to investigate the future star-formation history, as metals provide most of the gas cooling that will facilitate and sustain star formation. Aims. Our primary objective is to study the enrichment of the H  region and the interplay between star-formation history and metallicity evolution. Our secondary objective is to constrain the spatial-and time-scales over which the H  and H  regions are enriched, and the mass range of stars responsible for the heavy element production. Finally, we aim to examine the gas heating and cooling mechanisms in the H  region. Methods. We observed the most metal-poor star-forming galaxy in the Local Universe, I Zw 18, with the Cosmic Origin Spectrograph onboard Hubble. The abundances in the neutral gas are derived from far-ultraviolet absorption-lines (H , C , C *, N , O , ...) and are compared to the abundances in the H  region. Models are constructed to calculate the ionization structure and the thermal processes. We investigate the gas cooling in the H  region through physical diagnostics drawn from the fine-structure level of C + . Results. We find that H  region abundances are lower by a factor of ∼2 as compared to the H  region. There is no differential depletion on dust between the H  and H  region. Using sulfur as a metallicity tracer, we calculate a metallicity of 1/46 Z (vs. 1/31 Z in the H  region). From the study of the C/O, [O/Fe], and N/O abundance ratios, we propose that C, N, O, and Fe are mainly produced in massive stars. We argue that the H  envelope may contain pockets of pristine gas with a metallicity essentially null. Finally, we derive the physical conditions in the H  region by investigating the C * absorption line. The cooling rate derived from C * is consistent with collisions with H 0 atoms in the diffuse neutral gas. We calculate the star-formation rate from the C * cooling rate assuming that photoelectric effect on dust is the dominant gas heating mechanism. Our determination is in good agreement with the values in the literature if we assume a low dust-to-gas ratio (∼2000 times lower than the Milky Way value).

show abstract

“…the reviews by Rana 1991;Woosley et al 2002). In general type Ia supernovae are believed to yield most of the iron in the Galaxy while core-collapse supernovae would be responsible for the oxygen.…”

Section: Relative Supernova Yieldsmentioning

confidence: 99%

The metal contents of two groups of galaxies

Grange

Plaa

Kaastra

et al. 2011

A&A

View full text Add to dashboard Cite

Context. The hot gas in clusters and groups of galaxies is continuously being enriched with metals from supernovae and stars. It is well established that the enrichment of the gas with elements from oxygen to iron is mainly caused by supernova explosions. The origins of nitrogen and carbon are still being debated. Possible candidates include massive, metal-rich stars, early generations of massive stars, intermediate-or low-mass stars and asymptotic giant branch (AGB) stars. Aims. In this paper we accurately determine the metal abundances of the gas in the groups of galaxies NGC 5044 and NGC 5813, and discuss the nature of the objects that create these metals. We mainly focus on carbon and nitrogen. Methods. We use spatially-resolved high-resolution X-ray spectroscopy from XMM-Newton. For the spectral fitting, multitemperature hot gas models are used. Results. The abundance ratios of carbon over oxygen and nitrogen over oxygen that we find are high compared to the ratios in the stars in the disk of our Galaxy. The oxygen and nitrogen abundances we derive are similar to what has been found in earlier work on other giant ellipticals in comparable environments. We show that the iron abundances in both our sources have a gradient along the cross-dispersion direction of the reflection grating spectrometer (RGS). Conclusions. We conclude that it is unlikely that the creation of nitrogen and carbon takes place in massive stars, which end their lives as core-collapse supernovae, enriching the medium with oxygen because oxygen should then also be enhanced. Therefore we favour low-and intermediate-mass stars as sources of these elements. The abundances in the hot gas can be explained best by a 30-40% contribution of type Ia supernovae based on the measured oxygen and iron abundances and under the assumption of a Salpeter initial mass function (IMF).

show abstract

Chemical Evolution Of The Galaxy

Cited by 73 publications

References 0 publications

The star formation history of low-mass disk galaxies: A case study of NGC 300

The star formation history of low-mass disk galaxies: A case study of NGC 300

Chemical enrichment and physical conditions in I Zw 18

The metal contents of two groups of galaxies

Contact Info

Product

Resources

About