Dipankar P.K. Banerjee, Joseph A. Nuth, Karl A. Misselt, Watson P. Varricatt, David Sand, N. M. Ashok, K. Y.L. Su, G. H. Marion, Massimo Marengo

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


An eruptive nova-like event took place in 1994 in the stellar-merger candidate V4332 Sgr. Following the eruption, dust consisting of refractory silicate-rich dust grains containing a significant component of AlO bonding was formed sometime between 1998 and 2003. Observations using Spitzer between 2005 and 2009 show significant changes in the 10 μm silicate stretch feature. There is a deepening of the 10 μm silicate stretch as well as the development of a feature between about 13 and 20 μm consistent with a blend of the MgO and FeO stretching features and the O-Si-O bending mode of increasingly ordered silicate dust. Near-infrared observations show the presence of AlO and water vapor in the outflow in 2003, 2004, and 2005: the AlO has significantly decreased in spectra obtained in 2014 while the water vapor remains largely unchanged. An attempt is made to correlate these observations and understand the significance of these changes using DUSTY modeling. The observations appear consistent with the kinetically controlled condensation of highly underoxidized SiO/AlO/Fe/Mg dust grains in the outflow followed by the continuous evolution of the initial condensate due to thermal annealing and oxidation of the dust via reaction with ambient O, OH, and H2O in the expanding, cooling shell. Periodic monitoring of this dust shell over the mid-infrared spectral range could yield useful information on the evolution of underoxidized silicate condensates exposed to hot water vapor in more conventional circumstellar environments.

Original languageEnglish (US)
Article number109
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 1 2015


  • dust, extinction
  • infrared: stars
  • novae, cataclysmic variables
  • stars: individual (V4332 Sagittarii)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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