 |
 |
Astron. Astrophys. 358, 671-681 (2000)
Abundances of light elements in metal-poor stars
IV. [Fe/O] and [Fe/Mg] ratios and the history of star formation in the solar neighborhood
R.G. Gratton 1,
E. Carretta 1,
F. Matteucci 2,3 and
C. Sneden 4
1 Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
2 Università di Trieste, Dipartimento die Astronomia, Via G.B. Tiepolo 11, 31413 Trieste, Italy
3 SISSA/ISAS, via Beirut, 34014 Trieste, Italy
4 University of Texas at Austin and McDonald Observatory, USA
Received 28 February 2000 / Accepted 17 April 2000
Abstract
The accurate O, Mg and Fe abundances derived in previous papers of
this series from a homogeneous reanalysis of high quality data for a
large sample of stars are combined with stellar kinematics in order to
discuss the history of star formation in the solar neighborhood. We
found that the Fe/O and Fe/Mg abundance ratios are roughly constant in
the (inner) halo and the thick disk; this means that the timescale of
halo collapse was shorter than or of the same order of typical
lifetime of progenitors of type Ia SNe
(![[FORMULA]](img1.gif)
Gyr), this conclusion being
somewhat relaxed (referring to star formation in the individual
fragments) in an accretion model for the Galaxy formation. Both Fe/O
and Fe/Mg ratios raised by ![[FORMULA]](img2.gif)
dex
while the O/H and Mg/H ratios hold constant during the transition from
the thick to thin disk phases, indicating a sudden decrease in star
formation in the solar neighbourhood at that epoch. These results are
discussed in the framework of current views of Galaxy formation; they
fit in a scenario where both dissipational collapse and accretions
were active on a quite similar timescale.
Key words: stars:
abundances 
nuclear reactions, nucleosynthesis,
abundances
Galaxy: evolution
Send offprint requests to: R.G. Gratton
Contents
- 1. Introduction
- 2. Results
- 3. Chemical abundances and dynamics
- 4. The gap in [Fe/O] distribution
- 5. Comparison with models of galactic chemical evolution
- 6. Dissipational collapse and accretion
- Acknowledgements
- References
© European Southern Observatory (ESO) 2000
Online publication: June 8, 2000
helpdesk.link@springer.de