Long period variables detected by ISO in the Small Magellanic Cloud
Cioni M.-R.L., Blommaert J.A.D.L., Groenewgen M.A.T., Habing H.J., Hron J.,
Kerschbaum F., Loup C., Omont A., Waters L.B.F.M.,
Whitelock P.A., Zijlstra A.A.,
2003, A&A, 406, 51
Abstract
This article presents the study of the light-curves
extracted from the MACHO database of a sample of stars observed by the
Infrared Space Observatory in the Small Magellanic Cloud. These stars
belong to the ISO-Mini-Survey catalogue of the Magellanic Clouds
(ISO-MCMS, Loup et al. {in preparation}). Most of them are in the
asymptotic giant branch (AGB) and supergiant phases. The dominant
period and amplitude of pulsation have been derived and the stars have
been classified as Mira or Semi-Regular pulsators. Furthermore, the
cross-identification with near-infrared DENIS and 2MASS magnitudes
available within the ISO-MCMS allowed us: (i) to investigate the
properties of these stars in the combined near- and mid-infrared
colour-magnitude diagrams, (ii) to derive the bolometric magnitude by
integrating the spectral energy distribution and (iii) to estimate the
mass-loss rate. The stars have been divided into carbon- (C-) and
oxygen-rich (O-rich) using the (J-KS, KS) colour-magnitude diagram and
their period and amplitude distributions have been compared. C-rich
AGB stars have a sharp peak in their period distribution at about 250
days and have on average a larger amplitude than O-rich AGB
stars. This effect, not previously detected from the study of similar
stars in the Large Magellanic Cloud and in the Baade's window, might
be closely related to the metallicity of the environment in which the
stars have formed.
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