Luminosities and mass-loss rates of SMC and LMC AGB stars and Red Supergiants - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




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Abstract: Abridged Dust radiative transfer models are presented for 101 carbon starsand 86 oxygen-rich evolved stars in the Magellanic Clouds for which 5-35 \mum\{\it Spitzer} IRS spectra are available. The spectra are complemented withavailable optical and infrared photometry to construct the spectral energydistribution. A minimisation procedure is used to fit luminosity, mass-lossrate and dust temperature at the inner radius. Different effective temperaturesand dust content are also considered. Periods from the literature and from newOGLE-III data are compiled and derived. The O-rich stars are classified inforeground objects, AGB stars and Red Super Giants.For the O-rich stars silicates based on laboratory optical constants arecompared to -astronomical silicates-. Overall, the grain type by Volk and Kwok1988 fit the data best. However, the fit based on laboratory opticalconstants for the grains can be improved by abandoning the small-particlelimit. The influence of grain size, core-mantle grains and porosity areexplored.Relations between mass-loss rates and luminosity and pulsation period arepresented and compared to the predictions of evolutionary models, those byVassiliadis and Wood 1993 and their adopted mass-loss recipe, and those basedon a Reimers mass-loss law with a scaling of a factor of five. The Vassiliadisand Wood models describe the data better, although there are also somedeficiencies, in particular to the maximum adopted mass-loss rate.The OGLE-III data reveal an O-rich star in the SMC with a period of 1749days. Its absolute magnitude of $M { m bol}= -8.0$ makes it a good candidatefor a super-AGB star.



Author: M.A.T. Groenewegen, G.C. Sloan, I. Soszynski, E.A. Petersen

Source: https://arxiv.org/







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