Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-26T03:24:47.499Z Has data issue: false hasContentIssue false
  • English
  • Français

The primordial abundance of 4He from a large sample of low-metallicity H ii regions

Published online by Cambridge University Press:  23 April 2010

Yuri I. Izotov
Yuri I. Izotov*
Affiliation:
Main Astronomical Observatory, Ukrainian National Academy of Sciences, Zabolotnoho 27, Kyiv 03680, Ukraine email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

We determine the primordial helium mass fraction Yp using 1700 spectra of low-metallicity extragalactic H ii regions. This sample is selected from the Data Release 7 of the Sloan Digital Sky Survey, from European Southern Observatory archival data and from our own observations. We have considered known systematic effects which may affect the 4He abundance determination. They include collisional and fluorescent enhancements of He i recombination lines, underlying He i and hydrogen stellar absorption lines, collisional excitation of hydrogen lines, temperature and ionization structure of the H ii region. Monte Carlo methods are used to solve simultaneously the above systematic effects. We find a primordial helium mass fraction Yp = 0.2512 ± 0.0006(stat.) ± 0.0020 (syst.). This value is higher than the value given by Standard Big Bang Nucleosynthesis (SBBN) theory. If confirmed, it would imply slight deviations from SBBN.

Keywords

galaxies: abundancesgalaxies: irregulargalaxies: ISMISM: H ii regionsISM: abundances
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 5 , Symposium S268: Light Elements in the Universe , November 2009 , pp. 107 - 112
Copyright
Copyright © International Astronomical Union 2010

References

Abazajian, K., et al. 2009, ApJS, 182, 543CrossRefGoogle Scholar
Benjamin, R. A., Skillman, E. D., & Smits, D. P. 1999, ApJ, 514, 307CrossRefGoogle Scholar
Benjamin, R. A., Skillman, E. D., & Smits, D. P. 2002, ApJ, 569, 288CrossRefGoogle Scholar
Cardelli, J. A., Clayton, G. C., & Mathis, J. S. 1989, ApJ, 345, 245CrossRefGoogle Scholar
Dunkley, J., et al. 2009, ApJS, 180, 306CrossRefGoogle Scholar
Fukugita, M. & Kawasaki, M. 2006, ApJ, 646, 691CrossRefGoogle Scholar
Guseva, N. G., Izotov, Y. I., & Thuan, T. X. 2006, ApJ, 644, 890CrossRefGoogle Scholar
Guseva, N. G., Izotov, Y. I., Papaderos, P., & Fricke, K. J. 2007, A&A, 464, 885Google Scholar
Izotov, Y. I. & Thuan, T. X. 2004, ApJ, 602, 200 (IT04)CrossRefGoogle Scholar
Izotov, Y. I., Thuan, T. X., & Lipovetsky, V. A. 1994, ApJ, 435, 647CrossRefGoogle Scholar
Izotov, Y. I., Thuan, T. X., & Lipovetsky, V. A. 1997, ApJS, 108, 1CrossRefGoogle Scholar
Izotov, Y. I., Stasińska, G., Meynet, G., Guseva, N. G., & Thuan, T. X. 2006, A&A, 448, 955Google Scholar
Izotov, Y. I., Thuan, T. X., & Stasińska, G. 2007, ApJ, 662, 15CrossRefGoogle Scholar
Peimbert, M. & Torres-Peimbert, S. 1974, ApJ, 193, 327CrossRefGoogle Scholar
Peimbert, M. & Torres-Peimbert, S. 1976, ApJ, 203, 581CrossRefGoogle Scholar
Peimbert, M., Luridiana, V., & Peimbert, A. 2007, ApJ, 666, 636CrossRefGoogle Scholar
Porter, R. L., Bauman, R. P., Ferland, G. J., & MacAdam, K. B. 2005, ApJ, 622, L73CrossRefGoogle Scholar
Porter, R. L., Ferland, G. J., MacAdam, K. B., & Storey, P. J. 2009, MNRAS, 393, L36CrossRefGoogle Scholar
Press, W. H., Teukolsky, S. A., Vetterling, W. T.,& Flannery, B. P. 1992, Numerical Recipes in C, The Art of Scientific Computing /Second Edition/, Cambridge University PressGoogle Scholar
Spergel, D. N., Bean, R., Doré, O., et al. 2007, ApJS, 170, 377CrossRefGoogle Scholar
Stasińska, G. & Izotov, Y. I. 2001, A&A, 378, 817Google Scholar
Steigman, G. 2005, Physica Scripta, T121, 142CrossRefGoogle Scholar
Steigman, G. 2007, Annual Review of Nuclear and Particle Science, 57, 463CrossRefGoogle Scholar
Whitford, A. E. 1958, AJ, 63, 201CrossRefGoogle Scholar