The abundance of nitrogen in starburst nucleus galaxies

R. Coziol; R. E. Carlos Reyes; S. Considere; E. Davoust; T. Contini

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arXiv · astro-ph/9903279

The abundance of nitrogen in starburst nucleus galaxies

R. Coziol·R. E. Carlos Reyes·S. Considere·E. Davoust·T. Contini

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Abstract

We show that the excess of nitrogen emission observed in a large sample of Starburst Nucleus Galaxies (SBNGs) can only be explained at a given metallicity by an overabundance of nitrogen with respect to normal HII regions in the disks of late-type spirals. The N/O ratios in the SBNGs are comparable to the values found in the bulges of normal early-type spirals, which suggests that what we observe could be the main production of nitrogen in the bulges of these galaxies. The variation of the N/O ratio as a function of metallicity in SBNGs follows a primary + secondary relation, but the increase of nitrogen does not appear as a continuous process. In SBNGs, nitrogen is probably produced by different populations of intermediate-mass stars, which were formed during past sequences of bursts of star formation. This assumption pushes the origin of the main bursts 2-3 Gyrs back in the past. On a cosmological scale, this time interval corresponds to redshifts z = 0.2-0.3, where a significant increase of star formation activity occurred. The origin of the SBNG phenomenon would thus have cosmological implications, it would be related to a more active phase of star formation in the Universe sometime in its recent past.

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BibTeX RIS

R. Coziol, R. E. Carlos Reyes, S. Considere, E. Davoust, T. Contini. 1999-03-18. The abundance of nitrogen in starburst nucleus galaxies. https://arxiv.org/abs/astro-ph/9903279

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