The planetary nebula population of the Sagittarius dwarf spheroidal galaxy

Zijlstra, A. A.; Gęsicki, K.; Walsh, J. R.; Pequignot, D.; Hoof, P. A. M. van; Minniti, D.

doi:10.1111/j.1365-2966.2006.10338.x

Cited by 57 publications

(103 citation statements)

References 79 publications

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“…dSphs are marked with filled circles, dIrs with empty stars, NGC 147 average abundance with a filled square. Abundances determinations: NGC 147 (this work), LMC and SMC (Leisy & Dennefeld 2006), Sextans A and B (Magrini et al 2005), NGC 205, 185, Fornax (Richer & McCall 1995), Sagittarius (Zijlstra et al 2006), Leo A (Van Zee et al 2006), M32 (Stasinska et al 1998), NGC 6822, NGC 3109 (Leisy et al, in preparation). The almost diagonal line marks the luminosity–metallicity relation obtained from H ii regions (Van Zee et al 2006).…”

Section: The Luminosity–metallicity Relationship Of Dirs and Dsphsmentioning

confidence: 92%

The chemical content of nearby galaxies from planetary nebulae: NGC 147

Gonçalves

Magrini

Leisy

et al. 2007

Monthly Notices of the Royal Astronomical Society

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We report the results of spectroscopic observations, obtained with the GEMINI Multi-Object Spectrograph, of 8 planetary nebulae (PNe) in the dwarf spheroidal (dSph) galaxy NGC147, a companion of M31. The physico-chemical properties of the six brightest PNe (Corradi et al. 2005) were derived using both the empirical ICF method and photoionization modelling with CLOUDY. Different aspects of the evolution of low and intermediate mass stars in a low-metallicity environment are analysed using relationships between chemical abundances. In addition, certain features of the chemical evolution of NGC147 were examined. In particular, the mean metallicity of PNe, O/H=8.06 (corresponding to [Fe/H](PNe)~-0.97), is close to the metallicity of the old stellar population, [Fe/H]=-1.0 (Butler & Martinez-Delgado), suggesting a negligible chemical enrichment during a substantial amount of time. Finally, the luminosity-metallicity relationship for the dwarf galaxies of the Local Group is discussed. The location in the luminosity-metallicity diagram of dSphs does not exclude their formation from old dwarf irregular (dIrs) galaxies, but it does exclude their formation from the present time dIrs, since the differences between their metallicities are already present in their older populations. The offset in the luminosity-metallicity relationship indicates a faster enrichment of dSphs, and together with the different average abundance ratio [O/Fe] demonstrates the different star formation histories for these two types of galaxies.Comment: MNRAS accepted. 12 pages including 6 figures and 5 tables. Also available at http://www.astro.iag.usp.br/~denise

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Section: The Luminosity–metallicity Relationship Of Dirs and Dsphsmentioning

confidence: 92%

The chemical content of nearby galaxies from planetary nebulae: NGC 147

Gonçalves

Magrini

Leisy

et al. 2007

Monthly Notices of the Royal Astronomical Society

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“…Apart from these data, the only extant kinematic data are for planetary nebulae in the Magellanic Clouds (Dopita et al 1985;Dopita et al 1988) and the Sagittarius dwarf spheroidal (Zijlstra et al 2006). In all cases, data are available in [O iii]λ5007, and occasionally in other lines.…”

Section: Kinematicsmentioning

confidence: 99%

The Spectroscopic Properties of Bright Extragalactic Planetary Nebulae

Richer¹

2006

IAU

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Abstract. The properties of bright extragalactic planetary nebulae are reviewed based upon the results of low and high resolution spectroscopy. It is argued that bright extragalactic planetary nebulae from galaxies (or subsystems) with and without star formation have different distributions of central star temperature and ionization structure. As regards the chemical compositions, oxygen and neon are generally found to be unchanged as a result of the evolution of the stellar progenitors. Nitrogen enrichment may occur as a result of the evolution of the progenitors of bright planetary nebulae in all stellar populations, though this enrichment may be (more) random in old stellar populations. Helium abundances appear to be influenced by the chemical evolution of the host galaxy, with planetary nebulae in dwarf spheroidals having systematically elevated abundances. Neither the age nor the metallicity of the progenitor stellar population has a strong effect upon the kinematics observed for nebular shells. Both the range of expansion velocites, 8-28 km s −1 , and the typical expansion velocity, ∼18 km s −1 , are found to be relatively constant in all galaxies. On the other hand, bright planetary nebulae in the bulge of M31 have systematically higher expansion velocities than their counterparts in M31's disk. The expansion velocities show no trend with nebular Hβ luminosity, apart from a lack of large expansion velocities at the highest luminosities (the youngest objects), but appear to correlate with the 5007/Hβ ratio, at least until this ratio saturates. These results suggest a link between the evolution of the nebular shells and central stars of bright extragalactic planetary nebulae.

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“…No other stellar lines are clearly detected due to the stellar faintness. WR features and stellar emission lines have been detected in several extragalactic PN central stars, in particular in the dwarf spheroidal galaxies Sagittarius and Fornax (Zijlstra et al 2006;Kniazev et al 2007 Marco & Crowther 1998). This nebula presents a reddening higher than the average (c(Hβ) = 0.72), probably indicating the presence of significant quantities of dust in the nebula.…”

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The chemical composition of planetary nebulae and HII regions in NGC 3109

Peña¹,

Stasińska²,

Richer³

2007

A&A

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Aims. We present deep spectrophotometry for a sample of 8 planetary nebulae (PNe) and 12 HII regions distributed throughout the dwarf irregular galaxy NGC 3109, in order to analyze the chemical composition of both types of nebulae. Methods. We describe the observations and data reduction, and present line intensities for the nebular emission lines detected. The physical conditions and the abundances of He, O, Ne, N, S and Ar are derived, using the classical T e -based method. We confirm our previous identification of PNe and HII regions based on photometry, except for one object, which we argue is a compact HII region rather than a planetary nebula. Results. We find that the chemical composition of the interstellar medium in NGC 3109, as sampled by its HII regions, is remarkably uniform. The oxygen abundance is log O/H + 12 = 7.77 ± 0.07 in this galaxy, as compared to 8.05 ± 0.09 for the Small Magellanic Cloud (for which we rederived the metallicity in a homogeneous way). PNe show significantly higher oxygen abundances in NGC 3109: log O/H + 12 = 8.16 ± 0.19. Similarly to what has been suggested for some of the PNe in the Magellanic Clouds and other metal-poor galaxies, we argue that oxygen in the PNe in NGC 3109 is affected by dredge up in their progenitors. This could also be the case for neon, although the uncertainties for this element are bigger. Conclusions. From our analysis, we conclude that oxygen and neon are not always a safe indicator of the chemical composition of the interstellar medium at low metallicities. An alternative to the O and Ne enrichment in PNe is that the low metallicity in HII regions has been caused by dilution of the interstellar medium due to an interaction with a neighboring galaxy about a Gyr ago. The excitation patterns of the PNe in NGC 3109 are very different from the excitation patterns of PNe in other galaxies. This issue needs to be investigated further, as it implies that the evolution of PNe depends upon the properties of their progenitor stellar populations, which vary from galaxy to galaxy. This should affect the planetary nebula luminosity function and its use as a distance indicator. Regarding individual objects, we find that the planetary nebula named PN 14 shows clear Wolf-Rayet features, very low excitation and high density. Thus, it is similar to some of the galactic PNe ionized by late [WC] stars.

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The planetary nebula population of the Sagittarius dwarf spheroidal galaxy

Cited by 57 publications

References 79 publications

The chemical content of nearby galaxies from planetary nebulae: NGC 147

The chemical content of nearby galaxies from planetary nebulae: NGC 147

The Spectroscopic Properties of Bright Extragalactic Planetary Nebulae

The chemical composition of planetary nebulae and HII regions in NGC 3109

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