Galactic Metallicity Gradients Derived from a Sample of OB Stars

By S. Daflon, K. Cunha. 2004

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The distribution of stellar abundances along the Galactic disk is an important constraint for models of chemical evolution and Galaxy formation. In this study we derive radial gradients of C, N, O, Mg, Al, and Si, as well as S, from abundance determinations in young OB stars. Our database is composed of a sample of 69 members of 25 open clusters, OB associations, and H II regions with Galactocentric distances between 4.7 and 13.2 kpc. An important feature of this abundance database is the fact that the abundances were derived self-consistently in non-LTE using a homogeneous set of stellar parameters. Such an uniform analysis is expected to reduce the magnitude of random errors, as well as the influence of systematics in the gradients defined by the abundance and Galactocentric distance. The metallicity gradients obtained in this study are, in general, flatter than the results from previous recent abundance studies of early-type stars. The slopes are found to be between -0.031 (for oxygen) and -0.052 dex kpc-1 (for magnesium). The gradients obtained for the studied elements are quite similar, and if averaged they can be represented by a single slope of -0.042 ± 0.007 dex kpc-1. This value is generally consistent with an overall flattening of the radial gradients with time.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/c06ecb0f6db041cf3fd4748d65f9475627d13e66

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Citations in the corpus

A Spectroscopic Study of the Ancient Milky Way: F- and G-Type Stars in the Third Data Release of the Sloan Digital Sky Survey (2005, background): “The dashed line in Figure 13 illustrates the average metallicity gradient in thin-disk OB-type stars derived by Daflon & Cunha (2004) over the range in Galactocentric distance spanned by their study.”
Metallicity distributions of mono-age stellar populations of the Galactic disc from the LAMOST Galactic spectroscopic surveys (2018, unknown): “The [Fe/H] gradients in the radial and vertical directions have been determined with a variety of tracers, including OB stars (Daflon & Cunha 2004), Cepheid variables (Andrievsky et al. 2002; Luck, Kovtyukh & Andrievsky 2006), H II regions (Balser et al. 2011), open clusters (Chen, Hou & Wang 2003;…”
EXTRAGALACTIC CHEMICAL ABUNDANCES: DO H ii REGIONS AND YOUNG STARS TELL THE SAME STORY? THE CASE OF THE SPIRAL GALAXY NGC 300 (2009, background): “On the other hand, more recent studies of H II regions (Deharveng et al. 2000) and B stars (Daflon & Cunha 2004) find significantly flatter slopes for the oxygen gradient, −0.039± 0.005 and −0.031± 0.012 dex kpc−1, respectively, i.e. about a factor of two smaller.”
A NEW MECHANISM FOR RADIAL MIGRATION IN GALACTIC DISKS: SPIRAL–BAR RESONANCE OVERLAP (2009, background): “In addition, the ISMmetallicity has been well established to decrease with increasing galactic radius, r, due to a more efficient star formation and enrichment of the ISM in the central regions of galaxies (Wilson and Rood 1994; Daflon and Cunha 2004).”
The chemical composition of the Sun (2009, background): “The latter have also become more accurate, as reflected in greatly diminished uncertainties (e.g. Daflon & Cunha 2004, Morel 2008, Nieva & Przybilla 2006).”
OPTICAL SPECTROSCOPY AND NEBULAR OXYGEN ABUNDANCES OF THE SPITZER/SINGS GALAXIES (2010, unknown): “…(2006) reported a similar result for the Milky Way; they applied an empirical strong-line method (Pilyugin 2005) to observations of Galactic H ii regions and found excellent agreement with the stellar oxygen abundance gradient from Daflon & Cunha (2004) over a similar range of Galactocentric radii.”
The metallicity distribution of bulge clump giants in Baade’s window (2011, result): “These gradients are similar to the gradients observed in the youngest populations of the inner and outer discs (Daflon & Cunha 2004).”
Stellar population gradients in galaxy discs from the CALIFA survey - The influence of bars (2014, result): “Flatter abundance gradients in the younger population are also found in the Milky Way (Friel et al. 2002; Chen et al. 2003; Maciel et al. 2003; Daflon & Cunha 2004), although recent results by Maciel & Costa (2013) do not detect variations in the slope of the metallicity gradient measured in…”
Chemical evolution with radial mixing (2008, background): “…revision: some values derive from measurements of the metallicities of short-lived stars such as B stars and require downwards revision (e.g. Daflon & Cunha 2004), while others are inferred from measurements of the strengths of interstellar emission lines, and are not evidently affected by…”
CHEMICAL CARTOGRAPHY WITH APOGEE: LARGE-SCALE MEAN METALLICITY MAPS OF THE MILKY WAY DISK (2013, background): “…& Haywood 2010), HII regions (e.g., Balser et al. 2011), open clusters (e.g., Carrera & Pancino 2011; Frinchaboy et al. 2013), B stars (e.g., Daflon & Cunha 2004; Daflon et al. 2009), and surveys of main sequence stars (e.g., Cheng et al. 2012b for the Sloan Extension for Galactic…”
A FIRST CONSTRAINT ON THE THICK DISK SCALE LENGTH: DIFFERENTIAL RADIAL ABUNDANCES IN K GIANTS AT GALACTOCENTRIC RADII 4, 8, AND 12 kpc (2011, background): “Apart from a few studies of bright hot OB stars (e.g., Daflon & Cunha 2004) and Cepheids 1 This paper includes data gathered with the 6.5 meter Magellan Telescopes located at the Las Campanas Observatory, Chile (e.g., Luck et al. 2006), that trace the young disk stellar population, the only…”
Chemodynamical evolution of the Milky Way disk II: Variations with Galactic radius and height above the disk plane (2014, background): “2009; Luck and Lambert 2011; Lemasle et al. 2013), HII regions (e.g., Daflon and Cunha 2004; Stasińska et al. 2012 and references therein) and the more numerous young open clusters (e.g., Jacobson et al. 2011; Yong et al. 2012; Frinchaboy et al. 2013).”