Oxygen Abundances in Planetary Nebulae from O II Recombination Lines

Details Oxygen Abundances in Planetary Nebulae from O II Recombination Lines Oxygen Abundances in Planetary Nebulae from O II Recombination Lines

Dec 1997

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997aas...191.1506p&link_type=abstract

American Astronomical Society, 191st AAS Meeting, #15.06; Bulletin of the American Astronomical Society, Vol. 29, p.1233

Astronomy and Astrophysics

Astronomy

Scientific paper

We present new determinations of O(+2) /H(+) values for several planetary nebulae based on ratios of O II and H I recombination lines. These line ratios are nearly independent of the electron temperature, and therefore in principle should yield more accurate abundances than the collisionally excited [O III] lines, which are very sensitive to temperature and to the presence of temperature structure and inhomogeneities. The observations were made with a CCD spectrograph on the McDonald Observatory 2.\@7m Harlan Smith telescope, with a spectral resolving power of about R = 1700 and spectral coverage from 4000-4700 Angstroms, a region which contains many of the strongest O II recombination lines. Measurements of at least one usable O II line were obtained for 14 nebulae, with 5 or more O II lines measured for six objects. We find average values of log(O(+2) /H(+) ) + 12 = 9.1 -- 9.6, which is a factor of 1.5 -- 5 times greater than the solar O/H abundance of 8.9, and a factor of 3 -- 10 times greater than the typical nebular value of 8.6 which is derived from the [O III] lines. We discuss possible reasons for this discrepancy, including uncertainties in the line fluxes, uncertainties in the O II recombination coefficients, optical depth effects, and inhomogeneities in the physical conditions. We estimate the amplitude of the temperature fluctuations that would be required to bring the recombination-line O/H values into agreement with the forbidden-line O/H values.

Affiliated with

Also associated with

No associations

Rating

Oxygen Abundances in Planetary Nebulae from O II Recombination Lines 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 Oxygen Abundances in Planetary Nebulae from O II Recombination Lines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen Abundances in Planetary Nebulae from O II Recombination Lines will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1173215