The Chemical Composition of the 30 Doradus Nebula Derived from Very Large Telescope Echelle Spectrophotometry

Peimbert, Antonio

doi:10.1086/345793

Cited by 133 publications

(205 citation statements)

References 58 publications

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“…Models of Tsamis & Péquignot (2005) for 30 Dor predict that $92% of sulfur is in S iii and S iv, while 8% is due to other ionization stages, mostly S ii. Peimbert (2003) and Vermeij & van der Hulst (2002) find consistent results observationaly, with S ii/S iii ranging from 3% to 8.5%. In N66, the contribution of S ii is approximately 15% that of S iii (Peimbert et al 2000;Vermeij & van der Hulst 2002).…”

Section: Sulfur Ionization Structuresupporting

confidence: 66%

“…Optical observations of NGC 3603 show that the Ar iv contribution is indeed negligible, with Ar iv % 0:025 ð ÞAr iii (García- Rojas et al 2006). A similar value is found for 30 Dor, for which the contribution of Ar iv is $2%-3% that of Ar iii ( Peimbert 2003;Tsamis et al 2003). In N66 on the other hand, Ar iv could represent as much as 17% compared to Ar iii ( Peimbert et al 2000).…”

Section: Argon Ionization Structuresupporting

confidence: 53%

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Chemical Composition and Mixing in Giant HiiRegions: NGC 3603, 30 Doradus, and N66

Lebouteiller¹,

Bernard─Salas²,

Brandl³

et al. 2008

ApJ

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We investigate the chemical abundances of NGC 3603 in the Milky Way, of 30 Doradus in the Large Magellanic Cloud, and of N66 in the Small Magellanic Cloud. Mid-infrared observations with the Infrared Spectrograph on board the Spitzer Space Telescope allow us to probe the properties of distinct physical regions within each object, the central ionizing cluster, the surrounding ionized gas, photodissociation regions, and buried stellar clusters. We detect, and [Fe iii] lines and derive the ionic abundances. Based on the ionic abundance ratio ( Ne iii/H )/(S iii/H ), we find that the gas observed in the MIR is characterized by a lower degree of ionization than the gas observed in the optical spectra. We compute the elemental abundances of Ne, S, Ar, and Fe. We find that the -elements Ne, S, and Ar scale with each other. Our determinations agree well with the abundances derived from the optical. The Ne/S ratio is higher than the solar value in the three giant H ii regions and points toward a moderate depletion of sulfur on dust grains. We find that the neon and sulfur abundances display a remarkably small dispersion (0.11 dex in 15 positions in 30 Doradus), suggesting a relatively homogeneous ISM, even though smallscale mixing cannot be ruled out. Subject headingg s: H ii regions -infrared: ISM -ISM: atoms -ISM: individual ( NGC 3603, 30 Doradus, N66)

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Section: Sulfur Ionization Structuresupporting

confidence: 66%

Section: Argon Ionization Structuresupporting

confidence: 53%

Chemical Composition and Mixing in Giant HiiRegions: NGC 3603, 30 Doradus, and N66

Lebouteiller¹,

Bernard─Salas²,

Brandl³

et al. 2008

ApJ

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“…These velocities are higher than the isothermal sound speed in a warm ISM. In the case of 30 Doradus the average gas temperature is estimated to be around 10 4 K, with radiation pressure appearing to be negligible outside 10 pc from the central cluster R136 (Pellegrini et al 2011;Peimbert 2003). This results in an isothermal sound speed of order 10 km s −1 .…”

Section: Bow-shocks and The Ism In 30 Doradusmentioning

confidence: 96%

The VLT-FLAMES Tarantula Survey

Bressert

Bastian

Evans

et al. 2012

A&A

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Whether massive stars ( > ∼ 30 M ) can occasionally form in relative isolation (e.g. in clusters with M < 100 M ) or if they require a large cluster of lower-mass stars around them is a key test in the differentiation of star-formation theories as well as how the initial mass function of stars is sampled. Previous attempts to find O-type stars that formed in isolation were hindered by the possibility that such stars are merely runaways from clusters, i.e., their current isolation does not reflect their birth conditions. We introduce a new method to find O-type stars that are not affected by such a degeneracy. Using the VLT-FLAMES Tarantula Survey and additional high resolution imaging we have identified stars that satisfy the following constraints: 1) they are O-type stars that are not detected to be part of a binary system based on radial velocity (RV) time series analysis; 2) they are designated spectral type O7 or earlier; 3) their velocities are within 1σ of the mean of OB-type stars in the 30 Doradus region, i.e. they are not runaways along our line-of-sight; 4) the projected surface density of stars does not increase within 3 pc towards the O-star (no evidence for clusters); 5) their sight lines are associated with gaseous and/or dusty filaments in the interstellar medium (ISM); and 6) if a second candidate is found in the direction of the same filament with which the target is associated, both are required to have similar velocities. With these criteria, we have identified 15 stars in the 30 Doradus region, which are strong candidates for being high-mass stars that have formed in isolation. Additionally, we employed extensive Monte Carlo stellar cluster simulations to confirm that our results rule out the presence of clusters around the candidates. Eleven of these are classified as Vz stars, possibly associated with the zero-age main sequence. We include a newly discovered Wolf-Rayet star as a candidate, although it does not meet all of the above criteria.

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“…Figure 6 plots the C/O vs. O/H ratios for the complete sample of H ii regions where C and O abundances have been determined from RLs: HV (NGC 6822) and NGC 5408 from this work, Galactic H ii regions Esteban et al 2013), H ii regions in external spiral and irregular galaxies (Peimbert 2003;Esteban et al 2009) and the blue compact dwarf galaxy NGC 5253 (López-Sánchez et al 2007). The peculiar position of NGC 2363 is indicated in Figure 6 because it will be discussed later.…”

Section: The C/o Vs O/h Relationmentioning

confidence: 99%

Carbon and oxygen abundances from recombination lines in low-metallicity star-forming galaxies. Implications for chemical evolution★

Esteban

García‐Rojas

Carigi³

et al. 2014

Monthly Notices of the Royal Astronomical Society

111

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We present deep echelle spectrophotometry of the brightest emission-line knots of the star-forming galaxies He 2−10, Mkn 1271, NGC 3125, NGC 5408, POX 4, SDSS J1253−0312, Tol 1457−262, Tol 1924−416 and the H ii region Hubble V in the Local Group dwarf irregular galaxy NGC 6822. The data have been taken with the Very Large Telescope Ultraviolet-Visual Echelle Spectrograph in the 3100-10420Å range. We determine electron densities and temperatures of the ionized gas from several emission-line intensity ratios for all the objects. We derive the ionic abundances of C 2+ and/or O 2+ from faint pure recombination lines (RLs) in several of the objects, permitting to derive their C/H and C/O ratios. We have explored the chemical evolution at low metallicities analysing the C/O vs. O/H, C/O vs. N/O and C/N vs. O/H relations for Galactic and extragalactic H ii regions and comparing with results for halo stars and DLAs. We find that H ii regions in star-forming dwarf galaxies occupy a different locus in the C/O vs. O/H diagram than those belonging to the inner discs of spiral galaxies, indicating their different chemical evolution histories, and that the bulk of C in the most metal-poor extragalactic H ii regions should have the same origin than in halo stars. The comparison between the C/O ratios in H ii regions and in stars of the Galactic thick and thin discs seems to give arguments to support the merging scenario for the origin of the Galactic thick disc. Finally, we find an apparent coupling between C and N enrichment at the usual metallicities determined for H ii regions and that this coupling breaks in very low-metallicity objects.

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The Chemical Composition of the 30 Doradus Nebula Derived from Very Large Telescope Echelle Spectrophotometry

Cited by 133 publications

References 58 publications

Chemical Composition and Mixing in Giant HiiRegions: NGC 3603, 30 Doradus, and N66

Chemical Composition and Mixing in Giant HiiRegions: NGC 3603, 30 Doradus, and N66

The VLT-FLAMES Tarantula Survey

Carbon and oxygen abundances from recombination lines in low-metallicity star-forming galaxies. Implications for chemical evolution★

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