scholarly journals Dynamical and Chemical Evolution of IZw18

2004 ◽  
Vol 21 (2) ◽  
pp. 157-160
Author(s):  
Simone Recchi
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Dwarf Galaxy ◽  
Star Formation History ◽  
Intermediate Mass ◽  
Intermediate Mass Stars ◽  
Formation History ◽  
Type Ia ◽  
Ia Supernovae ◽  
Detailed Chemical

AbstractWe study the effect of different star formation regimes on the dynamical and chemical evolution of IZw18, the most metal-poor dwarf galaxy locally known. To do that we adopt a two-dimensional hydrocode coupled with detailed chemical yields originating from Type II and Type Ia supernovae and from intermediate-mass stars. Particular emphasis is devoted to the problem of mixing of metals. We conclude that, under particular conditions, cooling of metals occurs with a timescale of the order of 10 Myr, thus confirming the hypothesis of instantaneous mixing adopted in chemical evolution models. We try to draw conclusions about the star formation history and the age of the last burst in IZw18.

scholarly journals Chemical and Dynamical Evolution of IZw18

2004 ◽  
Vol 217 ◽  
pp. 196-197
Author(s):  
Simone Recchi
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Dwarf Galaxy ◽  
Chemical Properties ◽  
Dynamical Evolution ◽  
Intermediate Mass ◽  
Intermediate Mass Stars ◽  
Detailed Chemical

We study the effect of different star formation regimes on the dynamical and chemical evolution of the Dwarf Galaxy IZw18. To do that, we make use of a 2-D hydrocode coupled with detailed chemical yields originating from SNeII, SNeIa and low- and intermediate-mass stars. The results of our simulations are that IZw18 is a pretty young galaxy (we do not need to invoke stars older than 300 Myr in order to reproduce the chemical properties of this object) and the last burst of star formation occurred at most 15 Myr ago.

scholarly journals On the Star-formation History in the LMC: Observations of the Interstellar C18O/C17O Ratio

1999 ◽  
Vol 190 ◽  
pp. 275-276
Author(s):  
Arto Heikkilä ◽  
Lars E.B. Johansson ◽  
Hans Olofsson
Keyword(s):  
Star Formation ◽  
Massive Stars ◽  
Density Ratio ◽  
Abundance Ratio ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Intermediate Mass ◽  
Stellar Nucleosynthesis ◽  
Intermediate Mass Stars ◽  
Formation History

The re-cycling of gas between stars and the interstellar medium (ISM) leads to a gradual metal-enrichment of a galaxy. Accordingly, information on the chemical evolution of a galaxy, e.g., its star-formation history (SFH), is contained in the chemical composition of the ISM. In this context, the abundance ratio of the rare oxygen isotopes, 18O/17O (usually taken as the C18O/C17O column density ratio), appears to be a particularly promising probe of the SFH. According to present understanding of stellar nucleosynthesis, 17O is mainly produced in intermediate-mass stars (say a few to ten M⊙) while 18O is synthesised in massive stars (say >10M⊙) (e.g., Prantzos et al. 1996). Thus, the 18O/17O abundance ratio possibly reflects the relative number of massive stars compared to intermediate-mass stars, and thereby (qualitatively) constrains the SFH in terms of the average star-formation rate (SFR) and the initial mass-function (IMF). However, it should be remembered that the stellar nucleosynthesis of 17,18O is not yet fully understood, leaving room for other interpretations of the 18O/17O ratio.

scholarly journals The rate of type Ia Supernovae and the Star Formation History

2009 ◽  
Author(s):  
L. Greggio ◽  
E. Cappellaro ◽  
Giuliana Giobbi ◽  
Amedeo Tornambe ◽  
Gabriella Raimondo ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation History ◽  
Type Ia Supernovae ◽  
Formation History ◽  
Type Ia ◽  
Ia Supernovae

The Star Formation History of the Local Group Dwarf Galaxy Leo I

1999 ◽  
Vol 118 (5) ◽  
pp. 2245-2261 ◽  
Author(s):  
Carme Gallart ◽  
Wendy L. Freedman ◽  
Antonio Aparicio ◽  
Giampaolo Bertelli ◽  
Cesare Chiosi
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxy ◽  
Star Formation History ◽  
Formation History ◽  
History Of

scholarly journals Recovering the Star Formation History of IC1613 Dwarf Galaxy Using Evolved Stars

2018 ◽  
Vol 14 (S344) ◽  
pp. 77-80
Author(s):  
Seyed Azim Hashemi ◽  
Atefeh Javadi ◽  
Jacco Th. van Loon
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
Stellar Populations ◽  
Asymptotic Giant Branch ◽  
Star Formation History ◽  
Evolved Stars ◽  
Formation History ◽  
The Galaxy ◽  
Red Supergiants ◽  
Period Variable

AbstractDetermining the star formation history (SFH) is key to understand the formation and evolution of dwarf galaxies. Recovering the SFH in resolved galaxies is mostly based on deep colour–magnitude diagrams (CMDs), which trace the signatures of multiple evolutionary stages of their stellar populations. In distant and unresolved galaxies, the integrated light of the galaxy can be decomposed, albeit made difficult by an age–metallicity degeneracy. Another solution to determine the SFH of resolved galaxies is based on evolved stars; these luminous stars are the most accessible tracers of the underlying stellar populations and can trace the entire SFH. Here we present a novel method based on long period variable (LPV) evolved asymptotic giant branch (AGB) stars and red supergiants (RSGs). We applied this method to reconstruct the SFH for IC1613, an irregular dwarf galaxy at a distance of 750 kpc. Our results provide an independent confirmation that no major episode of star formation occurred in IC1613 over the past 5 Gyr.

scholarly journals STAR FORMATION HISTORY AND CHEMICAL EVOLUTION OF THE SEXTANS DWARF SPHEROIDAL GALAXY

2009 ◽  
Vol 703 (1) ◽  
pp. 692-701 ◽  
Author(s):  
Myung Gyoon Lee ◽  
In-Soo Yuk ◽  
Hong Soo Park ◽  
Jason Harris ◽  
Dennis Zaritsky
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Star Formation History ◽  
Formation History

scholarly journals The LMC Centre Unfolding

1999 ◽  
Vol 190 ◽  
pp. 357-358 ◽  
Author(s):  
A. Ardeberg ◽  
P. Linde ◽  
B. Gustafsson
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Star Formation History ◽  
Formation History

We study star formation history and chemical evolution in the LMC Bar centre. With the HST PC and WFC plus uvby photometry, we find 30% of the stars younger than 200 My and evidence for reduced star formation 3 to 0.2 Gy ago. The overall [Fe/H] is −0.5. Many stars older than 4 Gy contradict a very young Bar.

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