Chemical Abundances of the Galactic H
                    <scp>ii</scp>
                    Region NGC 3576 Derived from Very Large Telescope Echelle Spectrophotometry

García‐Rojas, J.; Esteban, C.; Peimbert, M.; Rodríguez, Mónica; Ruíz, M. T.; Peimbert, Antonio

doi:10.1086/421909

Cited by 95 publications

(103 citation statements)

References 68 publications

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“…We have used intensity ratios of several selected emission lines of spectra of Galactic H ii regions published by Esteban et al (2004Esteban et al ( , 2013 and García-Rojas et al (2004 Esteban et al (2013) and calculated by Copetti et al (2007). The distances are based on kinematical or photometrical methods and have typical uncertainties of less than 1 kpc (e.g.…”

Section: Observational Datamentioning

confidence: 99%

The radial abundance gradient of chlorine in the Milky Way

Esteban¹,

García‐Rojas²,

Pérez-Mesa³

2015

Mon. Not. R. Astron. Soc.

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We determine the radial abundance gradient of Cl in the Milky Way from H ii regions spectra. For the first time, the Cl/H ratios are computed by simply adding ionic abundances and not using an ionization correction factor (ICF ). We use a collection of published very deep spectra of Galactic H ii regions. We have re-calculated the physical conditions, ionic and total abundances of Cl and O using the same methodology and updated atomic data for all the objects. We find that the slopes of the radial gradients of Cl and O are identical within the uncertainties: −0.043 dex kpc −1 . This is consistent with a lockstep evolution of both elements. We obtain that the mean value of the Cl/O ratio across the Galactic disc is log(Cl/O) = −3.42 ± 0.06. We compare our Cl/H ratios with those determined from Cl 2+ abundances and using some available ICF schemes of the literature. We find that our total Cl abundances are always lower than the values determined using ICF s, indicating that those correction schemes systematically overestimate the contribution of Cl + and Cl 3+ species to the total Cl abundance. Finally, we propose an empirical ICF (Cl 2+ ) to estimate the Cl/H ratio in H ii regions.

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Section: Observational Datamentioning

confidence: 99%

The radial abundance gradient of chlorine in the Milky Way

Esteban¹,

García‐Rojas²,

Pérez-Mesa³

2015

Mon. Not. R. Astron. Soc.

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“…The identification and adopted laboratory wavelengths of the lines were obtained following several previous identifications in the literature (see García-Rojas et al 2004;Esteban et al 2004;Zhang et al 2005, and references therein).…”

Section: Line Intensities and Reddening Correctionmentioning

confidence: 99%

Faint recombination lines in Galactic PNe with a [WC] nucleus

García‐Rojas¹,

Peña²,

Peimbert³

2009

A&A

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Aims. We present spatially resolved high-resolution spectrophotometric data for the planetary nebulae PB 8, NGC 2867, and PB 6. We have analyzed two knots in NGC 2867 and PB 6 and one in PB 8. The three nebulae are ionized by [WC] type nuclei: early [WO] for PB 6 and NGC 2867 and [WC 5-6] in the case of PB 8. Our aim is to study the behavior of the abundance discrepancy problem (ADF) in this type of planetary nebula. Methods. We measured a large number of optical recombination (ORL) and collisionally excited lines (CEL), from different ionization stages (many more than in any previous work), thus, we were able to derive physical conditions from many different diagnostic procedures. We determined ionic abundances from the available collisionally excited and recombination lines. Based on both sets of ionic abundances, we derived total chemical abundances in the nebulae using suitable ionization correction factors. Results. From CELs, we have found abundances typical of Galactic disk planetary nebulae. Moderate ADF(O ++ ) were found for PB 8 (2.57) and NGC 2867 (1.63). For NGC 2867, abundances from ORLs are higher but still consistent with Galactic disk planetary nebulae. On the contrary, PB 8 presents a very high O/H ratio from ORLs. A high C/O was obtained from ORLs for NGC 2867; this ratio is similar to C/O obtained from CELs and with the chemical composition of the wind of the central star, indicating that there was no further C-enrichment in the star, relative to O, after the nebular material ejection. On the contrary, we found C/O < 1 in PB 8. Interestingly, we obtain (C/O) ORLs /(C/O) CELs < 1 in PB 8 and NGC 2867; this added to the similarity between the heliocentric velocities measured in [O iii] and O ii lines for our three objects argue against the presence of H-deficient metal-rich knots coming from a late thermal pulse event.

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“…We used the standard assumption, i.e., that I(Hβ) = 100, to compute the line intensity ratios. The identification and adopted laboratory wavelength of the lines, as well as their errors, were obtained following García-Rojas et al (2004) and Esteban et al (2004).…”

Section: Analysis Of the Spectramentioning

confidence: 99%

“…We note that we used an updated atomic dataset for O + , S + , and S ++ for NEBULAR. The references are indicated in Table 4 of García-Rojas et al (2004).…”

Section: Physical Conditions Of the Ionized Gasmentioning

confidence: 99%

Massive star formation in Wolf-Rayet galaxies

López-Sánchez

Esteban

2009

A&A

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Aims. We have performed a comprehensive multiwavelength analysis of a sample of 20 starburst galaxies that show the presence of a substantial population of very young massive stars, most of them classified as Wolf-Rayet (WR) galaxies. In this paper, the second of the series, we present the results of the analysis of long-slit intermediate-resolution spectroscopy of star-formation bursts for 16 galaxies of our sample. Methods. We study the spatial localization of the WR stars in each galaxy. We analyze the excitation mechanism and derive the reddening coefficient, physical conditions, and chemical abundances of the ionized gas. We study the kinematics of the ionized gas to check the rotation/turbulence pattern of each system. When possible, tentative estimates of the Keplerian mass of the galaxies are calculated. Results. Aperture effects and the exact positioning of the slit onto the WR-rich bursts seem to play a fundamental role in their detection. We check that the ages of the last star-forming burst estimated using optical spectra agree with those derived from Hα imagery. Our analysis shows that a substantial fraction of the galaxies exhibit evidence of perturbed kinematics. With respect to the results found in individual galaxies, we remark the detection of objects with different metallicity and decoupled kinematics in Haro 15 and Mkn 1199, the detection of tidal streams in IRAS 08208+2816, Tol 9, and perhaps in SBS 1319+579, and the development of a merging process in both SBS 0926+606 A and Tol 1457-262. Conclusions. All of these results -in combination with those obtained in Paper I -reinforce the hypothesis that interactions with or between dwarf objects is a very important mechanism in triggering massive-star formation in starburst galaxies, especially in dwarf ones. It must be highlighted that only deep and very detailed observations -as presented in this paper -can provide clear evidences that these subtle interaction processes are taking place.

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Chemical Abundances of the Galactic H ii Region NGC 3576 Derived from Very Large Telescope Echelle Spectrophotometry

Cited by 95 publications

References 68 publications

The radial abundance gradient of chlorine in the Milky Way

The radial abundance gradient of chlorine in the Milky Way

Faint recombination lines in Galactic PNe with a [WC] nucleus

Massive star formation in Wolf-Rayet galaxies

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