The Spitzer-IRS spectrum of SMP LMC 11

Abstract

We present the first mid-infrared spectra of SMP LMC 11 in the Large Magellanic Cloud. While this object resembles a planetary nebula in the optical, its infrared properties are more similar to an object in transition from the asymptotic giant branch to the planetary nebula phase. A warm dust continuum dominates the infrared spectrum. The peak emission corresponds to a mean dust temperature of 330 K. The spectrum shows overlapping molecular absorption bands from 12 to 17 um corresponding to acetylene and polyacetylenic chains and benzene. This is the first detection of C4H2, C6H2, C6H6 and other molecules in an extragalactic object. The infrared spectrum of SMP LMC 11 is similar in many ways to that of the pre-planetary nebula AFGL 618. The IRS spectrum shows little evidence of nitrogen-based molecules which are commonly seen in Galactic AGB stars. Polycyclic aromatic hydrocarbons are also absent from the spectrum. The detection of the [NeII] 12.8 um line in the infrared and other forbidden emission lines in the optical indicates that an ionized region is present.

5 pages (in emulateapj), 1 table, 2 figures. Accepted for publication in ApJ Letters

References in corpus (2)

• Spitzer observations of acetylene bands in carbon-rich AGB stars in the Large Magellanic Cloud
• A Post-AGB Star in the Small Magellanic Cloud Observed with the Spitzer Infrared Spectrograph

Cited by in corpus (5)

• High resolution mid-infrared spectroscopy of ultraluminous infrared galaxies
• The unusual hydrocarbon emission from the early carbon star HD 100764: The connection between aromatics and aliphatics
• Star formation in M33: Spitzer photometry of discrete sources
• A Post-AGB Star in the Small Magellanic Cloud Observed with the Spitzer Infrared Spectrograph
• SPITZER SAGE Observations of Large Magellanic Cloud Planetary Nebulae