Molecular Line Emissions from the Circumstellar Outflows of Oxygen-Rich Late-Type Stars

Details Molecular Line Emissions from the Circumstellar Outflows of Oxygen-Rich Late-Type Stars Molecular Line Emissions from the Circumstellar Outflows of Oxygen-Rich Late-Type Stars

Nov 1998

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998phdt........12c&link_type=abstract

Thesis (PHD). THE JOHNS HOPKINS UNIVERSITY , Source DAI-B 59/05, p. 2245, Nov 1998, 94 pages.

Mathematics

Probability

Scientific paper

I modeled the far infrared water and CO line emission from the circumstellar outflows of oxygen-rich late-type stars. The gas density, temperature, outflow velocity, and water abundance are determined self consistently, as a function of distance from the star. I then used the escape probability approximation to compute the level population in 84 water and 60 CO rotational states, and consequently obtained the line luminosity of a large number of far infrared rotational transitions. In agreement with previous modeling outflows, I find water rotational cooling to be the most important except in regions where it is photo-dissociated by the interstellar UV radiation. In contrast with previous modeling efforts, I find my predicted water line luminosity to be substantially lower. This is the result of my use of a more realistic water rotational cooling function and of my self consistent calculation of the temperature profile. For future reference, I have computed line luminosities for 21 models with different combinations of mass-loss rates and outflow velocities. I also present the first detection of thermal water emission from circumstellar outflows, observed by the Short Wavelength Spectrometer (SWS) of the recently launched Infrared Space Observatory (ISO). Applying the model developed here to the four SWS observed lines of the star W Hydrae, and to previous ground based observations of the CO (J = 4-3) line, I estimated the mass-loss rate of W Hya to be (1.6-4.8) ×10-6Msolar yr-1. Using the results from the M=3×10-6Msolar yr-1 model, I compared my predicted line fluxes with the thermal water lines observed by the Long Wavelength Spectrometer (LWS) of ISO and with previous ground observations of CO (J = 3-2), CO (J = 2-1), and CO (J = 1-0) lines. I find my prediction to agree with these observations to within a factor of two. Finally, I present Long Wavelength Spectrometer (LWS) observations of another star, NML Cyg. My model, however, underestimates the observed fluxes of the four water lines, over wide ranges of parameter space. This is likely due to the oversimplifying assumptions of the model which have been observed to be violated by NML Cyg.

Affiliated with

Also associated with

No associations

Rating

Molecular Line Emissions from the Circumstellar Outflows of Oxygen-Rich Late-Type Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Molecular Line Emissions from the Circumstellar Outflows of Oxygen-Rich Late-Type Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Molecular Line Emissions from the Circumstellar Outflows of Oxygen-Rich Late-Type Stars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-804869