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http://hdl.handle.net/20.500.12386/28115
Title: | AGB stars in the SMC: evolution and dust properties based on Spitzer observations | Authors: | Dell'Agli, Flavia D. A. García-Hernández VENTURA, Paolo SCHNEIDER, RAFFAELLA DI CRISCIENZO, Marcella C. Rossi |
Issue Date: | 2015 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 454 | Issue: | 4 | First Page: | 4235 | Abstract: | We study the population of asymptotic giant branch (AGB) stars in the Small Magellanic Cloud (SMC) by means of full evolutionary models of stars of mass 1Msun < M < 8Msun, evolved through the thermally pulsing phase. The models also account for dust production in the circumstellar envelope. We compare Spitzer infrared colours with results from theoretical modelling. We show that ~75% of the AGB population of the SMC is composed by scarcely obscured objects, mainly stars of mass M < 2.5Msun at various metallicity, formed between 700 Myr and 5 Gyr ago; ~ 70% of these sources are oxygen--rich stars, while ~ 30% are C-stars. The sample of the most obscured AGB stars, accounting for ~ 25% of the total sample, is composed almost entirely by carbon stars. The distribution in the colour-colour ([3.6]-[4.5], [5.8]-[8.0]) and colour-magnitude ([3.6]-[8.0], [8.0]) diagrams of these C-rich objects, with a large infrared emission, traces an obscuration sequence, according to the amount of carbonaceous dust in their surroundings. The overall population of C-rich AGB stars descends from 1.5-2Msun stars of metallicity Z=0.004, formed between 700 Myr and 2 Gyr ago, and from lower metallicity objects, of mass below 1.5Msun, 2-5 Gyr old. We also identify obscured oxygen-rich stars (M ~ 4-6Msun) experiencing hot bottom burning. The differences between the AGB populations of the SMC and LMC are also commented. | URI: | http://hdl.handle.net/20.500.12386/28115 | URL: | https://academic.oup.com/mnras/article/454/4/4235/1004057 | ISSN: | 0035-8711 | DOI: | 10.1093/mnras/stv2298 | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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File | Description | Size | Format | |
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stv2298.pdf | PDF editoriale | 3.09 MB | Adobe PDF | View/Open |
1510.01230.pdf | 7.76 MB | Adobe PDF | View/Open |
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