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OH/IR stars as tracers of Galactic populations
Published online by Cambridge University Press: 07 August 2017
Abstract
I discuss observable quantities of OH/IR stars and their interpretation. The strong 1612 MHz maser is found in about 1/2 of all the stars that reach the AGB and then have the following properties: they are oxygen–rich, of high–luminosity (3,000 → 30,000L ⊙), vary in luminosity with a long period (P>500 d), lose mass rapidly and have a metallicity high enough to form sufficient amounts of dust (the metallicity of the LMC is probably the lowest value sufficient to produce OH/IR stars). OH/IR stars can be several Gyr old. There are at least three different populations each characterized by different galactic orbits. (1) OH/IR stars in the galactic disk on almost circular orbits; (2) OH/IR stars in the galactic bulge on orbits of lower angular momentum; (3) OH/IR stars within 150 pc from the galactic center forming a rapidly rotating system.
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- Copyright © Kluwer 1993
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