Dissecting the Spitzer color-magnitude diagrams of extreme LMC AGB stars

Abstract

We trace the full evolution of low- and intermediate-mass stars ($1M_{\odot }\le M\le 8M_{\odot }$) during the Asymptotic Giant Branch (AGB) phase in the {\it Spitzer} two-color and color-magnitude diagrams. We follow the formation and growth of dust particles in the circumstellar envelope with an isotropically expanding wind, in which gas molecules impinge upon pre--existing seed nuclei, favour their growth. These models are the first able to identify the main regions in the {\it Spitzer} data occupied by AGB stars in the Large Magellanic Cloud (LMC). The main diagonal sequence traced by LMC extreme stars in the [3.6]-[4.5] vs. [5.8]-[8.0] and [3.6]-[8.0] vs. [8.0] planes are nicely fit by carbon stars models; it results to be an evolutionary sequence with the reddest objects being at the final stages of their AGB evolution. The most extreme stars, with [3.6]-[4.5] $>$ 1.5 and [3.6]-[8.0] $>$ 3, are 2.5-3 $M_{\odot }$ stars surrounded by solid carbon grains. In higher mass ($>3M_{\odot }$) models dust formation is driven by the extent of Hot Bottom Burning (HBB) - most of the dust formed is in the form of silicates and the maximum obscuration phase by dust particles occurs when the HBB experienced is strongest, before the mass of the envelope is considerably reduced.

arXiv comment5 pages, 2 figures, accepted for publication in MNRAS Letters

References in corpus (32)

• Spitzer Survey of the Large Magellanic Cloud, Surveying the Agents of a Galaxy's Evolution (SAGE) I: Overview and Initial Results
• Spitzer SAGE survey of the Large Magellanic Cloud II: Evolved Stars and Infrared Color Magnitude Diagrams
• Full computation of massive AGB evolution. I. The large impact of convection on nucleosynthesis
• Asymptotic Giant Branch evolution at varying surface C/O ratio: effects of changes in molecular opacities
• Massive AGB models of low metallicity: the implications for the self-enrichment scenario in metal poor Globular Clusters
• The Kr85 s-process Branching and the Mass of Carbon Stars
• Synthetic photometry for carbon rich giants, I. Hydrostatic dust-free models
• The origin of dust in high redshift QSOs: the case of SDSS J1148+5251
• Surveying the Agents of Galaxy Evolution in the Tidally-Stripped, Low Metallicity Small Magellanic Cloud (SAGE-SMC) II. Cool Evolved Stars
• User Manual for DUSTY
• Evolution of Thermally Pulsing Asymptotic Giant Branch Stars II. Dust production at varying metallicity
• Rubidium-Rich Asymptotic Giant Branch Stars
• The extinction law at high redshift and its implications
• AGB stars in the Magellanic Clouds. II. The rate of star formation across the LMC
• The Mass-Loss Return From Evolved Stars to The Large Magellanic Cloud VI: Luminosities and Mass-Loss Rates on Population Scales
• The AGB superwind speed at low metallicity
• Dust formation around AGB and SAGB stars: a trend with metallicity?
• The SAGE-Spec Spitzer Legacy program: The life-cycle of dust and gas in the Large Magellanic Cloud. Point source classification I
• Lithium and zirconium abundances in massive Galactic O-rich AGB stars
• A Digital Photometric Survey of the Magellanic Clouds: First Results From One Million Stars
• Dust from AGBs: relevant factors and modelling uncertainties
• The Mass-Loss Return From Evolved Stars to the LMC: Empirical Relations for Excess Emission at 8 and 24 μm
• Rb-rich Asymptotic Giant Branch stars in the Magellanic Clouds
• The mass-loss return from evolved stars to the Large Magellanic Cloud V. The GRAMS carbon-star model grid
• 2-Dust : a Dust Radiative Transfer Code for an Axisymmetric System
• Dust-driven Winds and Mass Loss of C-rich AGB Stars with subsolar Metallicities
• The Mass-Loss Return from Evolved Stars to the Large Magellanic Cloud IV: Construction and Validation of a Grid of Models for Oxygen-Rich AGB Stars, Red Supergiants, and Extreme AGB Stars
• Evolution of Thermally Pulsing Asymptotic Giant Branch Stars III. Dust production at supersolar metallicities
• Asymptotic Giant Branch stars at low metallicity: the challenging interplay between mass loss and molecular opacities
• Discovery of Extreme Carbon Stars in the Large Magellanic Cloud
• Dust formation in the winds of AGBs: the contribution at low metallicities
• Evolution and chemical yields of AGB stars: effects of low-temperature opacities

Cited by in corpus (24)

• AGB stars in the LMC: evolution of dust in circumstellar envelopes
• AGB stars in the SMC: evolution and dust properties based on Spitzer observations
• Circumstellar Dust Around AGB Stars and Implications for Infrared Emission from Galaxies
• AGB and SAGB stars: modelling dust production at solar metallicity
• The Large Magellanic Cloud as a laboratory for Hot Bottom Burning in massive Asymptotic Giant Branch stars
• Studying the evolution of AGB stars in the Gaia epoch
• Evolved stars in the Local Group galaxies - II. AGB, RSG stars and dust production in IC10
• The evolution of Galactic planetary nebula progenitors through the comparison of their nebular abundances with AGB yields
• On the nature of the most obscured C-rich AGB stars in the Magellanic Clouds
• Evolved stars in the Local Group galaxies. I. AGB evolution and dust production in IC 1613
• Understanding the evolution and dust formation of carbon stars in the LMC with a look at the JWST
• AGB dust and gas ejecta in extremely metal-poor environments
• Evolved stars in the Local Group galaxies - III. AGB and RSG stars in Sextans A
• Planetary Nebulae in the Small Magellanic Cloud
• New Post-AGB star models as tools to understand AGB evolution and nucleosynthesis
• Galactic planetary nebulae with precise nebular abundances as a tool to understand the evolution of asymptotic giant branch stars
• The Compact Star-Forming Complex at the Heart of NGC 253
• Understanding dust production and mass loss on the AGB phase using post-AGB stars in the Magellanic Clouds
• The Infrared Massive Stellar Content of M83
• Discovery of stars surrounded by iron dust in the LMC
• The intense production of silicates during the final AGB phases of intermediate mass stars
• Characterization of M-stars in the LMC in the JWST era
• A study of oxygen-rich post-AGB stars in the Milky Way to understand the production of silicates from evolved stars
• Gas and dust from extremely metal-poor AGB stars