2013MNRAS.436.1191T -
Mon. Not. R. Astron. Soc., 436, 1191-1200 (2013/December-1)
Stripping of nitrogen-rich AGB ejecta from interacting dwarf irregular galaxies.
TSUJIMOTO T. and BEKKI K.
Abstract (from CDS):
Many dwarf irregular galaxies (dIrrs) exhibit an unusually low N/O ratio in Hii regions. This ratio is broadly equivalent to the average level of Galactic extremely metal-poor stars, suggesting that N released from asymptotic giant branch (AGB) stars is missing in the present-day interstellar matter of these dIrrs. We find evidence for past tidal interactions in the properties of individual dIrrs exhibiting low N/O ratios. Accordingly, we propose that the ejecta of massive AGB stars that correspond to a major production site of N can be stripped from dIrrs that have undergone a strong interaction with a luminous galaxy. The physical process of its stripping is made up of two stages: (i) the ejecta of massive AGB stars in a dIrr are first merged with those of the bursting prompt Type Ia supernovae and pushed up together to the galaxy halo and (ii) subsequently through tidal interactions with a luminous galaxy, these ejecta are stripped from a dwarf galaxy's potential well. Our new chemical evolution models with stripping of AGB ejecta succeed in reproducing the observed low N/O ratio. Furthermore, we confirm that a tidal interaction is responsible for the efficient stripping of AGB ejecta from dIrrs by N-body+hydrodynamical simulations.
Abstract Copyright:
© 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2013)
Journal keyword(s):
galaxies: abundances - galaxies: dwarf - galaxies: evolution - galaxies: irregular
Simbad objects:
44
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