The beat Cepheids in the Magellanic Clouds: an analysis from the EROS-2 database - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




The beat Cepheids in the Magellanic Clouds: an analysis from the EROS-2 database - Astrophysics > Solar and Stellar Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: A number of microlensing dark-matter surveys have produced tens of millionsof light curves of individual background stars. These data provide anunprecedented opportunity for systematic studies of whole classes of variablestars and their host galaxies. We aim to use the EROS-2 survey of theMagellanic Clouds to detect and study the population of beat Cepheids BCs inboth Clouds. BCs pulsating simultaneously in the first overtone and fundamentalmodes FO-F or in the second and first overtone modes SO-FO are ofparticular interest. Using special software designed to search for periodicvariables, we have scanned the EROS-2 data base for variables in the typicalperiod range of Cepheids. Metallicities of FO-F objects were then calculatedfrom linear nonadiabatic convective stellar models. We identify 74 FO-F BCs inthe LMC and 41 in the SMC, and 173 and 129 SO-FO pulsators in the LMC and SMC,respectively; 185 of these stars are new discoveries. For nearly all the FO-Fobjects we determine minimum, mean, and maximum values of the metallicity. TheEROS data have expanded the samples of known BCs in the LMC by 31%, in the SMCby 110%. The FO-F objects provide independent measures of metallicities inthese galaxies. The mean value of metallicity is 0.0045 in the LMC and 0.0018in the SMC.



Author: J.B. Marquette, J.P. Beaulieu, J.R. Buchler, R. Szabo, P. Tisserand, S. Belghith, P. Fouque, E. Lesquoy, A. Milsztajn, A. Schwarz

Source: https://arxiv.org/







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