We performed multiwavelength observations of the young planetary nebula ( PN ) M1-11 and obtained its elemental abundances , dust mass , and the evolutionary status of the central star .
The AKARI /IRC , VLT/VISIR , and Spitzer /IRS spectra show features due to carbon-rich dust , such as the 3.3 , 8.6 , and 11.3 \mu m features due to polycyclic aromatic hydrocarbons ( PAHs ) , a smooth continuum attributable to amorphous carbon , and the broad 11.5 and 30 \mu m features often ascribed to SiC and MgS , respectively .
We also report the presence of an unidentified broad feature at 16–22 \mu m , similar to the feature found in Magellanic Cloud PNe with either C-rich or O-rich gas-phase compositions .
We identify for the first time in M1-11 spectral lines at 8.5 ( blended with PAH ) , 17.3 , and 18.9 \mu m that we attribute to the C _ { 60 } fullerene .
This identification is strengthened by the fact that other Galactic PNe in which fullerenes are detected , have similar central stars , similar gas-phase abundances , and a similar dust composition to M1-11 .
The weak radiation field due to the relatively cool central stars in these PNe may provide favorable conditions for fullerenes to survive in the circumstellar medium .
Using the photo-ionization code Cloudy , combined with a modified blackbody , we have fitted the \sim 0.1–90 \mu m spectral energy distribution and determined the dust mass in the nebula to be \sim 3.5 \times 10 ^ { -4 } M _ { \odot } .
Our chemical abundance analysis and SED model suggest that M1-11 is perhaps a C-rich PN with C/O ratio in the gas-phase of +0.19 dex , and that it evolved from a 1–1.5 M _ { \odot } star .