Mid-infrared Spectroscopic Observations of the Dust-forming Classical
  Nova V2676 Oph
  The dust-forming nova V2676 Oph is unique in that it was the first nova to
provide evidence of C_2 and CN molecules during its near-maximum phase and
evidence of CO molecules during its early decline phase. Observations of this
nova have revealed the slow evolution of its lightcurves and have also shown
low isotopic ratios of carbon (12C/13C) and nitrogen (14N/15N) in its nova
envelope. These behaviors indicate that the white dwarf (WD) star hosting V2676
Oph is a CO-rich WD rather than an ONe-rich WD (typically larger in mass than
the former). We performed mid-infrared spectroscopic and photometric
observations of V2676 Oph in 2013 and 2014 (respectively 452 and 782 days after
its discovery). No significant [Ne II] emission at 12.8 micron was detected at
either epoch. These provided evidence for a CO-rich WD star hosting V2676 Oph.
Both carbon-rich and oxygen-rich grains were detected in addition to an
unidentified infrared feature at 11.4 micron originating from polycyclic
aromatic hydrocarbon molecules or hydrogenated amorphous carbon grains in the
envelope of V2676 Oph.
