On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk

By K. Genovali, B. Lemasle, G. Bono, M. Romaniello, M. Fabrizio, I. Ferraro, G. Iannicola, C. D. Laney, M. Nonino, M. Bergemann and 8 more. 2014

133 citations recorded by the source corpus.

We present homogeneous and accurate iron abundances for 42 Galactic Cepheids based on high resolution (R ~ 38 000) high signal-to-noise ratio (S/N ≥ 100) optical spectra collected with UVES at VLT (128 spectra). The above abundances were complemented with high-quality iron abundances provided either by our group (86) or available in the literature. We were careful to derive a common metallicity scale and ended up with a sample of 450 Cepheids. We also estimated accurate individual distances for the entire sample by using homogeneous near-infrared photometry and the reddening free period-Wesenheit relations. The new metallicity gradient is linear over a broad range of Galactocentric distances (RG ~ 5-19 kpc) and agrees quite well with similar estimates available in the literature (-0.060 ± 0.002 dex/kpc). We also uncover evidence that suggests that the residuals of the metallicity gradient are tightly correlated with candidate Cepheid groups (CGs). The candidate CGs have been identified as spatial overdensities of Cepheids located across the thin disk. They account for a significant fraction of the residual fluctuations, and also for the large intrinsic dispersion of the metallicity gradient. We performed a detailed comparison with metallicity gradients based on different tracers: OB stars and open clusters. We found very similar metallicity gradients for ages younger than 3 Gyr, while for older ages we found a shallower slope and an increase in the intrinsic spread. The above findings rely on homogeneous age, metallicity, and distance scales. Finally, by using a large sample of Galactic and Magellanic Cepheids for which accurate iron abundances are available, we found that the dependence of the luminosity amplitude on metallicity is vanishing.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/49a1bd9d96ac791fa42ca2ddb3e9368a91bf23a8

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Citations in the corpus

Estimating stellar birth radii and the time evolution of Milky Way’s ISM metallicity gradient (2018, unknown): “…data: • Present-day ISM metallicity gradient of −0.07 dex/kpc - this is slightly steeper than observations of classical Cepheids (∼ 100 Myr old, e.g., Genovali et al. 2014, ∼ −0.06 dex/kpc); • ISM metallicity gradient always negative (with the possible exception for age > 10 Gyr) - must be true,…”
Using chemical tagging to redefine the interface of the Galactic disc and halo (2015, background): “Negative metallicity gradient are widely observed in the canonical thin disk both in small samples (e.g. Genovali et al. 2014) and large surveys (e.g. Cheng et al. 2012; Mikolaitis et al. 2014).”
SDSS IV MaNGA – metallicity and nitrogen abundance gradients in local galaxies (2017, methodology): “…al. 2015), O/B-type stars (Smartt & Rolleston 1997; Rolleston et al. 2000), Cepheids (Luck et al. 2003; Pedicelli et al. 2009; Lemasle et al. 2013; Genovali et al. 2014), open clusters (Magrini et al. 2009; Yong et al. 2012) and planetary nebulae (Maciel & Quireza 1999; Stanghellini et al. 2006).”
Measuring Radial Orbit Migration in the Galactic Disk (2018, methodology): “But if there is an important radial gradient in the metallicities (as observed in the Milky Way, e.g., Genovali et al. 2014) then extensive radius migration, scrambling the orbital radii of stars while keeping their [Fe/H] unchanged, could explain the lack of a relation between age, metallicity,…”
On the metallicity of open clusters. III. Homogenised sample (2015, methodology): “This approach was recently used by Genovali et al. (2014) to study the fine structure of the metallicity gradient based on Cepheids.”