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Please use this identifier to cite or link to this item: http://hdl.handle.net/10481/29036

Title: Gas flows, star formation and galaxy evolution
Authors: Beckman, John E.
Casuso, Emilio
Zurita, A.
Relaño, Mónica
Issue Date: 2004
Abstract: In the first part of this article we show how observations of the chemical evolution of the Galaxy: G- and K-dwarf numbers as functions of metallicity, and abundances of the light elements, D, Li, Be and B, in both stars and the interstellar medium (ISM), lead to the conclusion that metal poor HI gas has been accreting to the Galactic disc during the whole of its lifetime, and is accreting today at a measurable rate, ~2 Msun per year across the full disc. Estimates of the local star formation rate (SFR) using methods based on stellar activity, support this picture. The best fits to all these data are for models where the accretion rate is constant, or slowly rising with epoch. We explain here how this conclusion, for a galaxy in a small bound group, is not in conflict with graphs such as the Madau plot, which show that the universal SFR has declined steadily from z=1 to the present day. We also show that a model in which disc galaxies in general evolve by accreting major clouds of low metallicity gas from their surroundings can explain many observations, notably that the SFR for whole galaxies tends to show obvious variability, and fractionally more for early than for late types, and yields lower dark to baryonic matter ratios for large disc galaxies than for dwarfs. In the second part of the article we use NGC 1530 as a template object, showing from Fabry-Perot observations of its Halpha emission how strong shear in this strongly barred galaxy acts to inhibit star formation, while compression acts to stimulate it.
Sponsorship: The research discussed in this article was supported by grants AYA2001-0435 (Spanish Ministry of Science and Technology) and AYA2004-08251-C02-01 (Spanish Ministry of Education and Science). A. Zurita acknowledges support by the Consejería de Educación y Ciencia de la Junta de Andalucía, Spain.
Publisher: Springer
Series/Report no.: Astrophysics and Space Science Library;319
Keywords: Galaxy
Star formation
URI: http://hdl.handle.net/10481/29036
ISBN: 1-4020-2861-X
Rights : Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License
Citation: Beckman, J.E.; et al. Gas flows, star formation and galaxy evolution. En: D.L. Block; et al. (eds.), Penetrating bars through masks of cosmic dust: the hubble tuning fork strikes a new note. Dordrecht: Springer, 2004. pp. 119-138. (Astrophysics and Space Science Library; 319). [http://hdl.handle.net/10481/29036]
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