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CHAOS V: Recombination Line Carbon Abundances in M 101.
- Source :
-
Astrophysical Journal . 5/10/2020, Vol. 894 Issue 2, p1-9. 9p. - Publication Year :
- 2020
-
Abstract
- The CHemical Abundances Of Spirals (CHAOS) project is building a large database of Large Binocular Telescope (LBT) H ii region spectra in nearby spiral galaxies to use direct abundances to better determine the dispersion in metallicity as a function of galactic radius. Here, we present CHAOS LBT observations of C ii λ4267 emission detected in 10 H ii regions in M 101, and using a new photoionization model-based ionization correction factor, we convert these measurements into total carbon abundances. A comparison with M 101 C ii recombination line observations from the literature shows excellent agreement, and we measure a relatively steep gradient in log(C/H) of −0.37 ± 0.06 dex. The C/N observations are consistent with a constant value of log(C/N) = 0.84 with a dispersion of only 0.09 dex, which, given the different nucleosynthetic sources of C and N, is challenging to understand. We also note that when plotting N/O versus O/H, all of the H ii regions with detections of C ii λ4267 present N/O abundances at the minimum of the scatter in N/O at a given value of O/H. If the high surface brightness necessary for the detection of the faint recombination lines is interpreted as an indicator of H ii region youth, then this may point to a lack of nitrogen pollution in the youngest H ii regions. In the future, we anticipate that the CHAOS project will significantly increase the total number of C ii λ4267 measurements in extragalactic H ii regions. [ABSTRACT FROM AUTHOR]
- Subjects :
- *PHOTOIONIZATION
*SPIRAL galaxies
*CORRECTION factors
*CARBON
*POLLUTION
*TELESCOPES
Subjects
Details
- Language :
- English
- ISSN :
- 0004637X
- Volume :
- 894
- Issue :
- 2
- Database :
- Academic Search Index
- Journal :
- Astrophysical Journal
- Publication Type :
- Academic Journal
- Accession number :
- 143366352
- Full Text :
- https://doi.org/10.3847/1538-4357/ab86ae