skip to main content

Title: The gas-rich circumbinary disk of HR 4049. I. A detailed study of the mid-infrared spectrum

We present a detailed analysis of the mid-infrared spectrum of the peculiar evolved object HR 4049. The full Spitzer-IRS high-resolution spectrum shows a wealth of emission with prominent features from CO{sub 2} and H{sub 2}O and possible contributions from HCN and OH. We model the molecular emission and find that it originates from a massive (M ≳ 8 × 10{sup –3} M {sub ☉}), warm (T {sub ex} ≈ 500 K) and radially extended gas disk that is optically thick at infrared wavelengths. We also report less enrichment in {sup 17}O and {sup 18}O than previously found and a comparison of the Spitzer observations to earlier data obtained by the Short Wavelength Spectrometer on board the Infrared Space Observatory reveals that the CO{sub 2} flux has more than doubled in 10 yr time, indicating active and ongoing chemical evolution in the circumbinary disk. If the gas originates from interaction between the stellar wind and the dust, this suggests that the dust could be oxygen-rich in nature. The molecular gas plays a crucial role in the thermal properties of the circumbinary disk by allowing visible light to heat the dust and then trapping the infrared photons emitted by the dust. Thismore » results in higher temperatures and a more homogeneous temperature structure in the disk.« less
Authors:
;  [1]
  1. Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada)
Publication Date:
OSTI Identifier:
22348335
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON DIOXIDE; DUSTS; EMISSION; EVOLUTION; HYDROCYANIC ACID; INFRARED SPECTRA; INTERACTIONS; OXYGEN; OXYGEN 17; OXYGEN 18; PHOTONS; RESOLUTION; SPACE; SPECTROMETERS; STARS; STELLAR WINDS; THERMODYNAMIC PROPERTIES; TRAPPING; VISIBLE RADIATION; WAVELENGTHS