KECK HIRES SPECTROSCOPY OF EXTRAGALACTIC H ii REGIONS: C AND O ABUNDANCES FROM RECOMBINATION LINES

By C. Esteban, F. Bresolin, M. Peimbert, J. García-Rojas, A. Peimbert, A. Mesa-Delgado. 2009

141 citations recorded by the source corpus.

We present very deep spectrophotometry of 14 bright extragalactic H ii regions belonging to spiral, irregular, and blue compact galaxies. The data for 13 objects were taken with the High Resolution Echelle Spectrometer on the Keck I telescope. We have measured C ii recombination lines in 10 of the objects and O ii recombination lines in eight of them. We have determined electron temperatures from line ratios of several ions, especially those of low ionization potential. We have found a rather tight linear empirical relation between Te([N ii]) and Te([O iii]). We have found that O ii lines give always larger abundances than [O iii] lines. Moreover, the difference of both O++ abundance determinations—the so-called abundance discrepancy factor—is very similar in all the objects, with a mean value of 0.26 ± 0.09 dex, independent of the properties of the H ii region and of the parent galaxy. Using the observed recombination lines, we have determined the O, C, and C/O radial abundance gradients for three spiral galaxies: M33, M101, and NGC 2403, finding that C abundance gradients are always steeper than those of O, producing negative C/O gradients across the galactic disks. This result is similar to that found in the Milky Way and has important implications for chemical evolution models and the nucleosynthesis of C.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/a3927663593d081e088ac51f138b1b4e89d0ef94

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Citations in the corpus

Eliminating error in the chemical abundance scale for extragalactic H ii regions (2012, methodology): “Indeed, detailed studies that compared heavy elements abundances derived using both the Te method and the RL method in Galactic (Esteban et al. 2004; Garćıa-Rojas et al. 2005, 2006; Garćıa-Rojas & Esteban 2007; Mesa-Delgado et al. 2009b; Mesa-Delgado & Esteban 2010; Mesa-Delgado et al. 2011) and e”
RESOLVING THE ELECTRON TEMPERATURE DISCREPANCIES IN H ii REGIONS AND PLANETARY NEBULAE: κ-DISTRIBUTED ELECTRONS (2012, methodology): “For the extragalactic H II regions we have data for 30 Dor (Peimbert 2003), NGC5253 (López-Sanchez et al. 2012), NGC 595, NGC 604, VS 24, VS 44, NGC 2365 and K 932 (Esteban et al. 2009).”
THE MASS–METALLICITY RELATION WITH THE DIRECT METHOD ON STACKED SPECTRA OF SDSS GALAXIES (2012, background): “Also, the metallicities determined from optical recombination lines (e.g., C ii λ4267 and O ii λ4649) and far-IR fine-structure lines (e.g., [O iii]52, 88 μm) tend to be 0.2–0.3 dex higher than those from collisionally excited lines (Garcı́a-Rojas & Esteban 2007; Bresolin 2008; Esteban et al. 2009).”
THE MOSDEF SURVEY: ELECTRON DENSITY AND IONIZATION PARAMETER AT z ∼ 2.3 (2015, unknown): “…a literature search and identified 32 galactic and extragalactic HII regions observed at high spectral resolution (R ∼ 8, 000−23, 000) with detections of both the [O ii] and [S ii] doublets (Garćıa-Rojas et al. 2005, 2006, 2007; López-Sánchez et al. 2007; Esteban et al. 2009, 2013, 2014).”
NEW STRONG-LINE ABUNDANCE DIAGNOSTICS FOR H ii REGIONS: EFFECTS OF κ-DISTRIBUTED ELECTRON ENERGIES AND NEW ATOMIC DATA (2013, methodology): “For the extragalactic H ii regions, we have data for 30 Dor (Peimbert 2003), NGC 595 (López-Sánchez et al. 2007), NGC 595, NGC 604, VS 24, VS 44, NGC 2365, and K 932 (Esteban et al. 2009).”
New calibrations for abundance determinations in H ii regions (2016, background): “…Skillman (1985); Torres-Peimbert, Peimbert & Fierro (1989); Kinkel & Rosa (1994); Garnett & Kennicutt (1994); Kennicutt & Garnett(1996); van Zee et al.(1998); Luridiana et al. (2002); Kennicutt, Bresolin & Garnett(2003); Bresolin (2007); Esteban et al.(2009); Li, Bresolin & Kennicutt (2013).”
Deriving model-based Te-consistent chemical abundances in ionized gaseous nebulae (2014, background): “…E. Pérez-Montero which are around 104 times fainter than CELs, but they do not depend on temperature, lead to abundances 0.1-0.3dex higher both in Giant H ii regions (e.g. Esteban et al. 2009 and references therein) and even higher in planetary nebulae (e.g. Liu 2010 and references therein).”
New fully empirical calibrations of strong-line metallicity indicators in star forming galaxies (2016, methodology): “Typical discrepancies between Te and RLs based abundances are found to be of the order of 0.2-0.3 dex, with the first ones underestimating the latter (Garćıa-Rojas & Esteban 2007; Esteban et al. 2009).”
Chemical evolution with rotating massive star yields - I. The solar neighbourhood and the s-process elements (2018, unknown): “In any case, we emphasize that the [C/O] ratio of our models at low metallicity is clearly sub-solar, in agreement with observations of halo stars and low-metallicity HII regions (e.g. Esteban et al. 2009, 2014; Nissen et al. 2014; Nakajima & Sorahana 2016).”
OPTICAL SPECTROSCOPY AND NEBULAR OXYGEN ABUNDANCES OF THE SPITZER/SINGS GALAXIES (2010, methodology): “Unfortunately, deriving t2 is very challenging observationally; it has been measured in a relatively small number of metal-rich [12 + log (O/H)Te 8.1] Galactic and extragalactic H ii regions (Garcı́a-Rojas & Esteban 2007; Esteban et al. 2009, and references therein).”