Dust Production by Evolved Stars in the Magellanic Clouds

Abstract

Within the context of the hugely successful SAGE-LMC and SAGE-SMC surveys, Spitzer photometry observations of the Large and Small Magellanic Clouds have revealed millions of infrared point sources in each galaxy. The brightest infrared sources are generally dust producing and mass-losing evolved stars, and several tens of thousands of such stars have been classified. After photometrically classifying these objects, the dust production by several kinds of evolved stars -such as Asymptotic Giant Branch stars and Red Supergiants -can be determined. SAGE-Spec is the spectroscopic follow-up to the SAGE-LMC survey, and it has obtained Spitzer -IRS 5-40 µm spectroscopy of about 200 sources in the LMC. Combined with archival data from other programs, observations at a total of ∼1000 pointings have been obtained in the LMC, while ∼250 IRS pointings were observed in the SMC. Of these, a few hundred pointings represent dust producing and mass-losing evolved stars, covering a range in colors, luminosities, and thus mass-loss rates. Red Supergiants and O-rich and C-rich AGB stars -the main dust producers -are well represented in the spectroscopic sample. This paper will summarize what we know about the mineralogy of dust producing evolved stars, and discuss their relative importance in the total dust budget.

Galaxy Evolution Studies with the SPace IR Telescope for Cosmology and Astrophysics (SPICA): The Power of IR Spectroscopy

“…Unbiased, deep low-resolution (R∼50-120) SMI spectrophotometric surveys will be able to cover 10 deg 2 in 600 hrs. and detect 30,000 galaxies (Kaneda et al 2017).…”

“…In the following four sections we briefly address each of the first four questions, reserving detailed analysis of the role of SPICA in answering these to four companion articles: i) the role of AGN feeding and AGN feedback in galaxy evolution (González-Alfonso et al 2017b); ii) the chemical evolution of galaxies and the rise of metals and dust (Fernández-Ontiveros et al 2017); iii) dust obscured star-formation and accretion histories from reionization using SPICA unbiased photometric (Gruppioni et al 2017) and low spectral resolution spectroscopic surveys (Kaneda et al 2017); iv) the first stars and galaxies (Egami et al 2017). We will detail in Sect.…”

“…It forms in the dense, enriched atmospheres of evolved stars, novae, supernovae, and dense molecular clouds (Valiante et al 2009; Zhukovska & Henning 2013; Marassi et al 2015; Bocchio et al 2016) and is destroyed by shocks, sputtering, and intense radiation fields. However, its dominant formation and destruction channels in different environments are poorly understood (Kemper 2015; Matsuura et al 2011; Micelotta et al 2016). IR spectroscopy can uniquely measure the dust mass produced by evolved stars and supernovae in nearby galaxies, allowing a detailed study of the dust mineralogy and composition, via the mid-IR SiO 2 , FeO , FeS , and crystalline silicate features (see e.g., Spoon et al 2006; Rho et al 2008).…”