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

Journal Article · Wed Jan 01 04:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/780/1/41· OSTI ID:22348335

Malek, S. E.

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. This results in higher temperatures and a more homogeneous temperature structure in the disk.

• OSTI ID: 22348335
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 780; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
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