I am looking at the opacity of interstellar molecular clouds with an interest in the radiation problem thought to be-devil massive stars in their formation. So, I am asking my self if the opacity of the molecular clouds is proportional the geometric cross-sectional area defined by the sectional area covered by the mean intermolecular distance? I will be happy for an answer.
You need to better define your problem. Molecular opacities depend on the wavelength of light you are looking at, the types of molecules, and the temperature/density of the gas (for determining the population of the electronic states). If dust is present than Mie scattering may be important. There are many references about the cross sections. Perhaps you should look at hitran or another infrared radiative transfer code.
I believe opacity is a function of temperature, constituents and wavelength of observation, and not the geometric size of the cloud
Your model and your question are unclear. If you assume that stars form in isolation and that the process is spherically symmetric, then at some point no more material can be added to the star. However, it is unrealistic to assume either spherical symmetry or isolation. Angular momentum results in disks, and instabilities related to Raleigh-Taylor result in infall channels. Stars form in clusters, and seldom in isolation. I do not believe that re-examining opacity estimates will be productive.
@William Dean Pesnell, thank you for the answer, I will come back to this question when I have formulated a clear and concise question.
@Chika, thank you for the answer, I will come back to this question when I have formulated a clear and concise question.
@P. G. Wannier , thank you for the answer, I will come back to this question when I have formulated a clear and concise question.
@William Dean Pesnell, will I be right if I say opacity is not a directly measured quantity but is calculated using computer models?
Opacities can be calculated from measured cross sections or derived from first-principles quantum mechanical calculations. Many molecular cross sections used in astrophysics have been measured. Opacity implies some sort of average over energy states has been done. Radiation transfer calculations can (and probably should) be done in a set of frequency bins using the frequency dependent cross sections and the model radiances converted to measurable quantities.
- Badges
- Science topic