Spitzer observations of V4332 Sagittarii: Detection of Alumina Dust

Abstract

We present broad-band 24, 70 and 160 micron photometry, 5-35 micron and 55-90 micron spectra of the eruptive variable V4332 Sgr from Spitzer observations. The distinguishing feature of the 5-35 micron spectrum is an unusually broad absorption feature near 10 micron at the position generally associated with silicate-rich dust. Through radiative transfer modeling, we show that this broad feature cannot arise from silicates alone but requires the inclusion of alumina (Al2O3) as a dust condensate. The case for including Al2O3 is strengthened further by the presence of the AlO radical, a potentially important molecule in forming Al2O3. The present detection indicates that porous alumina manifests itself through a broadening of the 9.7 micron silicate feature and additionally displays, on the shoulder of the silicate feature, a component at ~11.5 micron. We discuss how further observations of V4332 Sgr may have the potential of verifying some general predictions of the dust condensation process.

arXiv comment4 pages, 2 figures in ApJ style; to be published in ApJ Letters

References in corpus (12)

• The Infrared Spectrograph on the Spitzer Space Telescope
• Reduction Algorithms for the Multiband Imaging Photometer for Spitzer
• An energetic stellar outburst accompanied by circumstellar light echoes
• The mysterious eruption of V838 Mon
• User Manual for DUSTY
• Eruptions of the V838 Mon type: stellar merger versus nuclear outburst models
• Nova Sagittarii 1994 #1 (V4332 Sagittarii): The Discovery and Evolution of an Unusual Luminous Red Variable Star
• V4332 Sagittarii revisited
• Remarkable changes in the near-infrared spectrum of the nova-like variable V4332 Sgr
• V4332 Sgr in 'Quiescence'
• L & M band infrared studies of V4332 Sagittarii - detection of the water-ice absorption band at 3.05 microns and the CO fundamental band in emission
• Spitzer Observations of V838 Monocerotis: Detection of a Rare Infrared Light Echo

Cited by in corpus (11)

• Shock-powered light curves of luminous red novae as signatures of pre-dynamical mass loss in stellar mergers
• The Dusty Aftermath of the V1309 Sco Binary Merger
• V4332 Sagittarii: A circumstellar disc obscuring the main object
• Properties of the post in-spiral common envelope ejecta II: dust formation
• The A-X infrared bands of Aluminum Oxide in stars: search and new detections
• Evolution of the dust in V4332 Sagittarii
• Optical spectropolarimetry of V4332 Sagittarii
• CK Vul: a smorgasbord of hydrocarbons rules out a 1670 nova (and much else besides)
• Strong linear polarization of V4332 Sgr: a dusty disc geometry
• Rotational spectroscopy of AlO: Low N transitions of astronomical interest in the X^2 Sigma^+ state
• The Infrared Evolution of Dust in V838 Monocerotis