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LibraryM.A.T. Groenewegen (Royal Obs. of Belgium) & G.C. Sloan (STScI, UNC, Cornell)
2018, A&A, 609, 114
Full manuscript available locally (PDF).
You can also download the long version (PDF), with all of the tables and figures from the appendices.
Context.
Mass loss is one of the fundamental properties of asymptotic
giant branch (AGB) stars, and through the enrichment of the
interstellar medium, AGB stars are key players in the life
cycle of dust and gas in the universe. However, a
quantitative understanding of the mass-loss process is still
largely lacking.
Aims.
To investigate mass loss and luminosity in a large sample of
evolved stars in several Local Group galaxies with a wide
variety of metallicities and star-formation histories: the
Small and Large Magellanic Cloud, and the Fornax, Carina,
and Sculptor dwarf spheroidal galaxies (dSphs).
Methods.
Dust radiative transfer models are presented for 225 carbon
stars and 171 oxygen-rich evolved stars in the Magellanic
Clouds and a few nearby dSphs for which spectra from the
infrared Spectrograph on Spitzer are available. The
spectra are complemented with available optical and infrared
photometry to construct spectral energy distributions. A
minimisation procedure is used to determine luminosity and
mass-loss rate (MLR). Pulsation periods are derived for a
large fraction of the sample based on a re-analysis of
existing data.
Results.
New deep K-band data from the VMC survey and multi-epoch
data from IRAC (at 4.5µm) and AllWISE and NEOWISE have
allowed us to derive pulsation periods longer than 1000 days for
some of the most heavily obscured and reddened objects. We
derive (dust) MLRs and luminosities for the entire sample. The
estimated MLRs can differ significantly from estimates for the
same objects in the literature due due to differences in adopted
optical constants (up to factors of 5) and details in the
radiative transfer modelling. Updated parameters for the
super-AGB candidate MSX SMC 055 (IRAS 00483-7347) are presented.
Its current mass is estimated to be 8.5 +/- 1.6 solar masses,
suggesting an initial mass well above 8 solar masses in
agreement with estimates based on its large Rubidium abundance.
Using synthetic photometry, we present and discuss color-color
and color-magnitude diagrams which can be expected from the
James Webb Space Telescope.
Last modified 18 February, 2018. © Gregory C. Sloan and others.