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                              G C N E W S
                             * Newsflash *

            - The Newsletter for Galactic Center Research -

gcnews@aoc.nrao.edu                      http://www.aoc.nrao.edu/~gcnews
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Vol. 24, No. 5                                              May 11, 2006


Recently submitted papers:
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1) Near-IR Spectroscopy of OH/IR stars in the Galactic Centre 
  (Vanhollebeke et al., A&A)
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Email    : evelien@ster.kuleuven.be
Title    : Near-IR Spectroscopy of OH/IR stars in the Galactic Centre
Author(s): E. Vanhollebeke (1) and J.A.D.L. Blommaert (1) and M. 
           Schultheis (2) and B. Aringer (3) and A. Lanccon (4)
Institute: (1) Leuven , Observatoire de Besanccon, Wien and Strasbourg
Paper    : A&A accepted for publication on 18/04/2006

Abstract:
Galactic Centre (GC) OH/IR stars can be, based on the expansion 
velocities of their circumstellar shells, divided into two groups which 
are kinematically different and therefore are believed to have evolved 
from different stellar populations. To study the metallicity 
distribution of the OH/IR stars population in the GC on basis of a 
theoretical relation between EW(Na), EW(Ca) and EW(CO) and the 
metallicity. For 70 OH/IR stars in the GC, we obtained near-IR spectra. 
The equivalent line widths of \ionNai, \ionCai, \element[][12]CO(2,0) 
and the curvature of the spectrum around 1.6 micron due to water 
absorption are determined. The near-IR spectrum of OH/IR stars is 
influenced by several physical processes. OH/IR stars are variable 
stars suffering high mass-loss rates. The dust that is formed around 
the stars strongly influences the near-IR spectra and reduces the 
equivalent line widths of \ionNai, \ionCai. A similar effect is caused 
by the water content in the outer atmosphere of the OH/IR star. Because 
of these effects, it is not possible with our low resolution 
near-infrared spectroscopy to determine the metallicities of these 
stars.
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