The Distribution of Heavy Elements in Spiral and Elliptical Galaxies

Henry, R. B. C.; Worthey, Guy

doi:10.1086/316403

Cited by 327 publications

(341 citation statements)

References 175 publications

(303 reference statements)

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“…Recent work on open cluster stars confirms these results (Friel 1999, Phelps, this conference), and also data on B stars, as recently discussed by Smartt and Rolleston (1997), Gummersbach et al (1998), and Smartt (this conference), in contradiction with earlier work on these objects, which reported essentially flat gradients. The radial variations of O/H, S/H, Ne/H and Ar/H are consistent with essentially constant ratios of S/O, Ne/O and Ar/O from PN and HII regions, as can be seen from Table 1 and from a recent discussion on the gradients in the Galaxy and in other galaxies (Henry and Worthey 1999).…”

Section: Abundance Gradientssupporting

confidence: 84%

“…The second group of abundances in Table 1 shows abundances relative to oxygen of those elements (Ne, S, Ar, Cl) that are not produced during the evolution of the progenitor stars, so that they can be considered as representative of the interstellar medium at the time of formation of these stars. Except for halo (type IV) PN, all objects have essentially constant ratios, a result that has been confirmed for S, Ne and Ar for HII regions both galactic and extragalactic (Henry and Worthey 1999). The ratio N/O is also included, as it is used to distinguish between type I and non-type I nebulae.…”

Section: The Galactic Diskmentioning

confidence: 87%

“…The first item is relatively well established (cf. Maciel 1996, Henry and Worthey 1999, and it seems clear that an average gradient of −0.05 to −0.07 dex/kpc can be observed in the Galaxy for O/H, S/H, Ne/H and Ar/H. The PN derived gradient (Maciel and Quireza 1999, Maciel and Köppen 1994, Amnuel 1993, Pasquali and Perinotto 1993, Köppen et al 1991) is close to -and slightly lower than -the well known gradient observed from HII regions in the Galaxy (Shaver et al 1983, Afflerbach et al 1997) and in other spiral galaxies (Kennicutt andGarnett 1996, Ferguson et al 1998).…”

Section: Abundance Gradientsmentioning

confidence: 99%

“…According to Henry and Worthey (1999), these discrepancies could be caused by local abundance fluctuations due to unmixed ejecta from recent supernova events.…”

Section: The Halomentioning

confidence: 99%

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Planetary Nebulae: Abundances and Abundance Gradients

Maciel¹

2000

The Evolution of the Milky Way

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Section: Abundance Gradientssupporting

confidence: 84%

Section: The Galactic Diskmentioning

confidence: 87%

Section: Abundance Gradientsmentioning

confidence: 99%

“…According to Henry and Worthey (1999), these discrepancies could be caused by local abundance fluctuations due to unmixed ejecta from recent supernova events.…”

Section: The Halomentioning

confidence: 99%

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Planetary Nebulae: Abundances and Abundance Gradients

Maciel¹

2000

The Evolution of the Milky Way

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“…Radial abundance gradients in the Galaxy have been determined by a variety of objects, including HII regions, planetary nebulae (PN), B stars, open clusters and cepheids (Henry & Worthey 1999;Maciel 2000;Rolleston et al 2000). Several elements have been investigated, especially oxygen, sulphur, neon and argon in photoionized nebulae (Maciel & Quireza 1999;Deharveng et al 2000) and iron in open cluster stars and cepheids (Friel 1999;Andrievsky et al 2002aAndrievsky et al , 2002b.…”

Section: Introductionmentioning

confidence: 99%

An estimate of the time variation of the O/H radial gradient from planetary nebulae

Maciel¹,

Costa²,

Uchida³

2002

A&A

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Abstract. Radial abundance gradients are a common feature of spiral galaxies, and in the case of the Galaxy both the magnitude of the gradients and their variations are among the most important constraints of chemical evolution models. Planetary nebulae (PN) are particularly interesting objects to study the gradients and their variations. Owing to their bright emission spectra, they can be observed even at large galactocentric distances, and the derived abundances are relatively accurate, with uncertainties of about 0.1 to 0.2 dex, particularly for the elements that are not synthesized in their progenitor stars. On the other hand, as the offspring of intermediate mass stars, with main sequence masses in the interval of 1 to 8 solar masses, they are representative of objects with a reasonable age span. In this paper, we present an estimate of the time variation of the O/H radial gradient in a sample containing over 200 nebulae with accurate abundances. Our results are consistent with a flattening of the O/H gradient roughly from −0.11 dex/kpc to −0.06 dex/kpc during the last 9 Gyr, or from −0.08 dex/kpc to −0.06 dex/kpc during the last 5 Gyr.

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The G-dwarf problem in the solar neighbourhood: a statistical approach within a inhomogeneous, simple model

Caimmi

2000

Astron. Nachr.

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In dealing with the G‐dwarf problem in the solar neighbourhood, simple comoving models of chemical evolution are generalized on two respects, assuming that star formation occurs: (i) within discrete regions instead of a continuous interstellar medium, and (ii) via stochastic processes instead of a uniform generation, with the additional hypotheses: (iii) mass conservation, (iv) instantaneous recycling, and (v) instantaneous mixing within the system at the end of a fixed time step, in connection with identical regions. In the special case of the expected evolution, when the number of star‐forming regions equals the expected value of the related, binomial distribution, the gas mass fraction shows an exponential time dependence, the oxygen mass fraction a linear time dependence, and the star formation rate (related to the system) a linear dependence on the gas mass fraction, i.e. the gas density, whatever the star formation rate (related to a region) may be, provided the corresponding parameters are independent of evolution. In addition, it is shown that the dependence of oxygen gas mass fraction on gas mass fraction remains unchanged with respect to a simple model. Two main classes of theoretical age‐metallicity relation (TAMR) are analysed and discussed, according if the contribution to an assigned metallicity bin comes from long‐lived stars which are born during all the, or only a fraction of, time steps. It is found that, under some simplifying assumptions, the theoretical, differential, G‐dwarf metallicity distribution (TGD) has the same expression as in simple models, in connection with the main body of the TAMR. An application is made for the solar neighbourhood, and the input parameters are constrained to both the empirical age‐metallicity relation (EAMR) and the empirical, differential, G‐dwarf metallicity distribution (EGD). A different, power‐law, initial mass function (IMF) is allowed during and after disk formation. A power‐law steeper than the Salpeter IMF, which fits the Scalo IMF, is necessary to ensure a lower stellar mass limit above the stellar Jeans mass. An acceptable fit to the EAMR is provided by models where the ratio of oxygen yield, and lower stellar mass limit, during and after disk formation, range from about one half to about three halves. On the other hand, a fit to the EGD allows models where the IMF changes only slightly, or remains unchanged, during and after disk formation. Then a solution to the G‐dwarf problem demands, in the light of the current model, nothing but an initial, substructured disk made of pre‐enriched material, with same metallicity as the lower limit detected in G dwarfs belonging to the sample under consideration. Several runs are made in different situations, related to either constant number of regions or constant mass of a region, separately during and after disk formation. Significant statistical fluctuations are found when the number of regions is low enough, i.e. of the order of ten. A sharp peak exhibited by the EGD cannot be interpreted in terms o...

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The Distribution of Heavy Elements in Spiral and Elliptical Galaxies

Cited by 327 publications

References 175 publications

Planetary Nebulae: Abundances and Abundance Gradients

Planetary Nebulae: Abundances and Abundance Gradients

An estimate of the time variation of the O/H radial gradient from planetary nebulae

The G-dwarf problem in the solar neighbourhood: a statistical approach within a inhomogeneous, simple model

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