2020A&A...643L..15F -
Astronomy and Astrophysics, volume 643, L15-15 (2020/11-1)
Detection of infrared fluorescence of carbon dioxide in R Leonis with SOFIA/EXES.
FONFRIA J.P., MONTIEL E.J., CERNICHARO J., DEWITT C.N. and RICHTER M.J.
Abstract (from CDS):
We report on the detection of hot CO2 in the O-rich asymptotic giant branch star R Leo based on high spectral resolution observations in the range 12.8-14.3µm carried out with the Echelon-cross-Echelle Spectrograph (EXES) mounted on the Stratospheric Observatory for Infrared Astronomy (SOFIA). We found ≃240 CO2 emission lines in several vibrational bands. These detections were possible thanks to a favorable Doppler shift that allowed us to avoid contamination from telluric CO2 features. The highest excitation lines involve levels at an energy of ≃7000K. The detected lines are narrow (average deconvolved width ≃2.5km/s) and weak (usually ≤10% the continuum). A ro-vibrational diagram shows that there are three different populations, warm, hot, and very hot, with rotational temperatures of ≃550, 1150, and 1600K, respectively. From this diagram, we derived a lower limit for the column density of ≃2.2x1016cm–2. Further calculations based on a model of the R Leo envelope suggest that the total column density can be as large as 7.0x1017cm–2 and the abundance with respect to H2≃2.5x10–5. The detected lines are probably formed due to the de-excitation of CO2 molecules from high energy vibrational states, which are essentially populated by the strong R Leo continuum at 2.7 and 4.2µm.
Abstract Copyright:
© ESO 2020
Journal keyword(s):
stars: AGB and post-AGB - stars: individual: R Leo - stars: abundances - circumstellar matter - line: identification - surveys
Simbad objects:
6
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