Probing the possibility of a C-12/C-13 galactic abundance gradient

Details Probing the possibility of a C-12/C-13 galactic abundance gradient Probing the possibility of a C-12/C-13 galactic abundance gradient

Apr 1990

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990nascp3061..331h&link_type=abstract

In NASA, Ames Research Center, Carbon in the Galaxy: Studies from Earth and Space p 331-332 (SEE N90-27562 21-88)

Physics

Carbon Isotopes, Early Stars, Gradients, Interstellar Extinction, Isotope Effect, Spectra, Analogies, Galaxies, Homogeneity, Nuclear Fusion, Observatories, Sensitivity, Telescopes, Visual Observation

Scientific paper

High S/N (equal to or greater than 500) observations of interstellar CH+ with the 3.0 m telescope were performed at Lick Observatory and with the 4.0 m telescope at CTIO, of the reddened, early-type stars HD 183143, HD 24432, and HD 157038 in an effort to probe the existence of a C-12/C-13 abundance gradient in our Galaxy. Previous very high quality optical observations of interstellar CH+ toward five stars within 1 kpc of the Sun have yielded a precise weighted mean C-12/C-13 isotope ratio of 43 plus or minus 4 (1 sigma) (Hawkins, Jura, and Meyer 1985; Hawkins and Jura 1987). The isotope ratios derived toward four lines of sight in the local ISM are uniform within 12 percent. The similarity among these carbon isotope ratios determined in diffuse clouds possessing different physical conditions precludes the possibility that the CH+ molecule is suffering from isotope selective effects in these regions. The precise C-12/C-13 derivable from high quality observations of (12)CH+ and (13)CH+ provide the unique opportunity to probe the homogeneity of the ISM in a large scale and the history of nucleosynthesis in our Galaxy. Since CH+ seems to be the most sensitive probe of C-12/C-13 in the diffuse ISM, observations toward more distant stars located up to 2.5 kpc from the Sun are the best way to study the possibility of a Galactic (C-12/C-13) abundance gradient. The researcher obtained 4232 angstrom data toward all three of the stars mentioned above, 3957 angstrom data toward HD 183143 and HD 157038, and 3745 angstrom data toward HD 157038. Because of the poorer quality of the HD 24432 spectrum, and its weaker CH+ absorption lines, the satellite (13)CH+ line was not detected, and thus only a lower limit on the C-12/C-13 ratio toward this star was obtained. The results obtained from careful reduction and analysis of the data toward these stars in the Northern and Southern Hemispheres are presented.

Affiliated with

Also associated with

No associations

Rating

Probing the possibility of a C-12/C-13 galactic abundance gradient 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 Probing the possibility of a C-12/C-13 galactic abundance gradient, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Probing the possibility of a C-12/C-13 galactic abundance gradient will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1382432