Line intensities for CH and their application to stellar atmospheres.

Details Line intensities for CH and their application to stellar atmospheres. Line intensities for CH and their application to stellar atmospheres.

Nov 1996

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996a%26a...315..204j&link_type=abstract

Astronomy and Astrophysics, v.315, p.204-211

Astronomy and Astrophysics

Astrophysics

45

Stars: Atmospheres, Stars: Carbon, Molecular Data

Scientific paper

We have performed a complete computation of the bound-bound transitions that can take place in the CH molecule among the four lowest electronic states. The results of the computation is stored in the form of a line list of 112,821 lines (for each of the isotopes ^12^C^1^H and ^13^C^1^H) of the infrared transition X^2PI-X^2PI and the three electronic transitions A^2DELTA-X^2PI, B^2SIGMA^-^-X^2PI, and C^2SIGMA^+^-X^2PI. The dipole moment function and the electronic transition moments are assumed to be identical for the two isotopes, whereas the isotopic shift in the frequency is computed for each individual line. For each transition is given the lower and the upper quantum numbers, the wavenumber of the transition, the gf-value, the excitation energy, and the isotopic shift. The list contains a total of 22492 lines from the X-X transition between 905cm^-1^ and 24650cm^-1^ (4060A-11.0μm), 72702 lines from the A-X transition between 333cm^-1^ and 35110cm^-1^ (2850A-30.0μm), 5928 lines from the B-X transition between 1012cm^-1^ and 27698cm^-1^ (3610A-1.0μm), and 13445 lines from the C-X transition between 7103cm^-1^ and 40367cm^-1^ (2480A-1.4μm). The corresponding partition function to be used in connection with our line list is calculated as function of temperature. Finally, we have computed a small grid of model atmospheres for C/O{in}[0.43;1.35], T_effin[2800;5800], Z{in}[310^-4^;1]Zsun_, and log(g){in}[0.0;4.5]. This covers most of the very wide range of spectral types which are known to show spectral features due to CH, i.e. spectral class F to M, including various types of the chemically peculiar stars. We show that CH has a strong cooling effect (as strong as the well known cooling due to CO) on models of metal-poor stars. The spectral features of CH is seen primarily in the regions 2800A to 5000A (due to the C-X, B-X, and the A-X systems) and from 3.3μm to 5.3μm (due to the vibrational-rotational transitions). The most pronounced spectral feature due to CH is the so-called G-band (λ=~4300A; due to the 0-0 vibrational transition in the A-X system). We analyse the behaviour of the G-band intensity in our model atmospheres as function of T_eff_, gravity, metallicity, and C/O ratio.

Affiliated with

Also associated with

No associations

Rating

Line intensities for CH and their application to stellar atmospheres. 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 Line intensities for CH and their application to stellar atmospheres., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Line intensities for CH and their application to stellar atmospheres. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1143494