Issue |
A&A
Volume 381, Number 1, JanuaryI 2002
|
|
---|---|---|
Page(s) | L25 - L28 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20011554 | |
Published online | 15 January 2002 |
Letter to the Editor
The origin of primary nitrogen in galaxies
Geneva Observatory, 1290 Sauverny, Switzerland
Corresponding author: G. Meynet, Georges.Meynet@obs.unige.ch
Received:
24
October
2001
Accepted:
8
November
2001
We investigate the role of stellar axial rotation on
the nitrogen nucleosynthesis at low metallicities Z. For this purpose,
we have calculated models with initial masses between 2 and 60 at
from the zero age sequence to the phase of thermal pulses for models below or equal to 7
,
and up to the end of central C–burning for the more massive stars.
The models include all the main physical
effects of rotation. We show that intermediate mass stars with rotation naturally
reproduce the occurrence and amount of primary
nitrogen in the early star generations in the Universe. We identify two reasons why rotating models
at low Z produce primary 14N: 1) Since the stars lose less angular momentum, they rotate faster. Simultaneously,
they are more compact, thus differential rotation and shear mixing are stronger.
2) The H–burning shell has a much higher temperature and is thus closer to the core, which favours mixing between the two.
Key words: physical data and processes: nucleosynthesis / stars: evolution / stars: rotation
© ESO, 2002
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