The chemistry of extragalactic carbon stars

Abstract

Prompted by the ongoing interest in Spitzer Infrared Spectrometer spectra of carbon stars in the Large Magellanic Cloud, we have investigated the circumstellar chemistry of carbon stars in low-metallicity environments. Consistent with observations, our models show that acetylene is particularly abundant in the inner regions of low metallicity carbon-rich AGB stars -- more abundant than carbon monoxide. As a consequence, larger hydrocarbons have higher abundances at the metallicities of the Magellanic Clouds than in stars with solar metallicity. We also find the oxygen and nitrogen chemistry is suppressed at lower metallicity, as expected. Finally, we calculate molecular line emission from carbon stars in the Large and Small Magellanic Cloud and find that several molecules should be readily detectable with the Atacama Large Millimeter Array at Full Science operations.

Accepted for publication in the Monthly Notices of the Royal Astronomical Society (MNRAS)

References in corpus (18)

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• Too little radiation pressure on dust in the winds of oxygen-rich AGB stars
• A Problem with the Clustering of Recent Measures of the Distance to the Large Magellanic Cloud
• A Spitzer mid-infrared spectral survey of mass-losing carbon stars in the Large Magellanic Cloud
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• Molecules and dust production in the Magellanic Clouds
• Spitzer spectroscopy of carbon stars in the Small Magellanic Cloud
• Dust-driven Winds and Mass Loss of C-rich AGB Stars with subsolar Metallicities
• A spectral line survey in the 2 mm and 1.3 mm windows toward the carbon rich envelope of IRC +10216
• Spitzer observations of acetylene bands in carbon-rich AGB stars in the Large Magellanic Cloud
• The abundance of SiS in circumstellar envelopes around AGB stars
• Effects of Metallicity on the Chemical Composition of Carbon Stars
• The distribution of SiO in the circumstellar envelope around IRC+10216
• The Dust-to-Gas Ratio in the Small Magellanic Cloud Tail
• A Broadband Study of Galactic Dust Emission
• The distribution of H13CN in the circumstellar envelope around IRC+10216

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• Observations of the Planetary Nebula SMP LMC 058 with the JWST MIRI Medium Resolution Spectrometer
• An improved chemical scheme for the reactions of atomic oxygen and simple unsaturated hydrocarbons - implications for star-forming regions
• Eyes in the sky: Interactions between AGB winds and the interstellar magnetic field
• A Spitzer Space Telescope survey of extreme Asymptotic Giant Branch stars in M32
• Infrared variable stars in the compact elliptical galaxy M32