A new and homogeneous metallicity scale for Galactic classical Cepheids II. The abundance of iron and alpha elements

Abstract

Classical Cepheids are the most popular distance indicators and tracers of young stellar populations. The key advantage is that they are bright and they can be easily identified in Local Group and Local Volume galaxies. Their evolutionary and pulsation properties depend on their chemical abundances. The main aim of this investigation is to perform a new and accurate abundance analysis of two tens of calibrating Galactic Cepheids using high spectral resolution (R$\sim$40,000-115,000) and high S/N spectra ($\sim$400) covering the entire pulsation cycle. We focus our attention on possible systematics affecting the estimate of atmospheric parameters and elemental abundances along the pulsation cycle. We cleaned the line list by using atomic transition parameters based on laboratory measurements and by removing lines that are either blended or display abundance variations along the pulsation cycle. The spectroscopic approach that we developed brings forward small dispersions in the variation of the atmospheric parameters ($\sigma$($T_{\mathrm{eff}}$)$\sim$50 K, $\sigma$($\log g$)$\sim$0.2 dex, and $\sigma$($\xi$)$\sim$0.2 km/s) and in the abundance of both iron ($\lesssim$ 0.05 dex) and alpha elements ($\lesssim$0.10 dex) over the entire pulsation cycle. We also provide new and accurate effective temperature templates by splitting the calibrating Cepheids into four different period bins, ranging from short to long periods. For each period bin, we performed an analytical fit with Fourier series providing $\theta =5040/T_{\mathrm{eff}}$ as a function of the pulsation phase. The current findings are a good viaticum to trace the chemical enrichment of the Galactic thin disk by using classical Cepheids and a fundamental stepping stone for further investigations into the more metal-poor regime typical of Magellanic Cepheids.

arXiv comment31 pages, 23 figures (out of which 11 are in the appendices A and B), to be published in the Astronomy & Astrophysics journal

References in corpus (77)

• The chemical composition of the Sun
• Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• The chemical make-up of the Sun: A 2020 vision
• An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per cent
• Abundance Gradients and the Formation of the Milky Way
• Calibration of the Tip of the Red Giant Branch (TRGB)
• A new code for automatic determination of equivalent widths: Automatic Routine for line Equivalent widths in stellar Spectra (ARES)
• Evolution, Explosion and Nucleosynthesis of Core Collapse Supernovae
• Resolving the Hubble Tension with New Early Dark Energy
• The Distribution of the Elements in the Galactic Disk III. A Reconsideration of Cepheids from l = 30 to 250 Degrees
• The influence of chemical composition on the properties of Cepheid stars. II-The iron content
• ARES v2 - new features and improved performance
• On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk
• Both accurate and precise gf-values for FeII lines
• Chemistry of the Sagittarius Dwarf Galaxy: a Top-Light IMF, Outflows and the R-Process
• Nucleosynthesis and the Inhomogeneous Chemical Evolution of the Carina Dwarf Galaxy
• Intermediate-mass star models with different helium and metal contents
• Insights into the Cepheid distance scale
• Improved Ti II log(gf) Values and Abundance Determinations in the Photospheres of the Metal-Poor Star HD 84937
• Sulphur and zinc abundances in Galactic stars and damped Lyman-alpha systems
• Abundance gradients in the Milky Way for alpha elements, Iron peak elements, Barium, Lanthanum and Europium
• A re-classification of Cepheids in the Gaia Data Release 2
• The Distribution of the Elements in the Galactic Disk II. Azimuthal and Radial Variation in Abundances from Cepheids
• Fe I Oscillator Strengths for the Gaia-ESO Survey
• Cepheid pulsation models at varying metallicity and DY/DZ
• High resolution spectroscopy for Cepheids distance determination. I. Line asymmetry
• Elemental Abundance Ratios in Stars of the Outer Galactic Disk. III. Cepheids
• Fe I Oscillator Strengths for Transitions from High-lying Even-Parity Levels
• Galactic abundance gradients from Cepheids: alpha and heavy elements in the outer disk
• On the distance of the Magellanic Clouds using Cepheid NIR and optical-NIR Period Wesenheit Relations
• The Cepheid period -- luminosity -- metallicity relation based on Gaia DR2 data
• Theoretical models for Bump Cepheids
• On the alpha-element gradients of the Galactic thin disk using Cepheids
• Sulphur abundance in Galactic stars
• The Cepheid mass discrepancy and pulsation-driven mass loss
• The Milky Way Cepheid Leavitt law based on Gaia DR2 parallaxes of companion stars and host open cluster populations
• On the RR Lyrae stars in globulars: IV. $\omega$ Centauri Optical UBVRI Photometry
• On the evolutionary and pulsation mass of Classical Cepheids: III. the case of the eclipsing binary Cepheid CEP0227 in the Large Magellanic Cloud
• The Eclipsing Binary Cepheid OGLE-LMC-CEP-0227 in the Large Magellanic Cloud: pulsation modelling of light and radial velocity curves
• New NIR light-curve templates for classical Cepheids
• The Chemical Compositions of Non-Variable Red and Blue Field Horizontal Branch Stars
• The Gaia-ESO Survey: Galactic evolution of sulphur and zinc
• The influence of metallicity on the Leavitt Law from geometrical distances of Milky Way and Magellanic Clouds Cepheids
• On the metallicity distribution of classical Cepheids in the Galactic inner disk
• A new comprehensive set of elemental abundances in DLAs III. Star formation histories
• A critical reassessment of the fundamental properties of GJ 504: Chemical composition and age
• Baade-Wesselink distances and the effect of metallicity in classical cepheids
• Sulphur abundances from the SI near-infrared triplet at 1045 nm
• Classical Cepheid period-Wesenheit-metallicity relation in the Gaia bands
• Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey: I. HARPS-N@TNG spectroscopy of 47 Classical Cepheid and 1 BL Her variables
• GIANO Y-band spectroscopy of dwarf stars: Phosphorus, Sulphur, and Strontium abundances
• Fe I oscillator strengths for transitions from high-lying odd-parity levels
• Stellar population astrophysics (SPA) with the TNG. Revisiting the metallicity of Praesepe (M44)
• On the neutron-capture elements across the Galactic thin disk using Cepheids
• On the Use of Field RR Lyrae as Galactic Probes. III. The $\alpha$-element abundances
• Integral Field Spectroscopy of AGN Absorption Outflows: Mrk 509 and IRAS F04250-5718
• Atomic transition probabilities for UV and blue lines of Fe II and abundance determinations in the photospheres of the Sun and metal-poor star HD 84937
• Theoretical fits of the δCephei light, radius and radial velocity curves
• Detailed chemical composition of classical Cepheids in the LMC cluster NGC 1866 and in the field of the SMC
• Using classical Cepheids to study the far side of the Milky Way disk: I. Spectroscopic classification and the metallicity gradient
• Period-Age-Metallicity and Period-Age-Color-Metallicity relations for Classical Cepheids: an application to the Gaia EDR3 sample
• On the Period--Luminosity--Metallicity relation of Classical Cepheids
• Chemical Compositions of Field and Globular Cluster RR Lyrae Stars: I. NGC 3201
• First metallicity determination from Near-Infrared spectra for five obscured Cepheids discovered in the inner Disk
• Sulfur and zinc abundances of red giant stars
• On a new and homogeneous metallicity scale for Galactic classical Cepheids - I. Physical parameters
• Using classical Cepheids to study the far side of the Milky Way disk. II. The spiral structure in the first and fourth Galactic quadrants
• Effective temperatures of red supergiants estimated from line-depth ratios of iron lines in the YJ bands, 0.97--1.32 micron
• On the Use of Field RR Lyrae as Galactic Probes. V. Optical and radial velocity curve templates
• Spectroscopic properties of a two-dimensional time-dependent Cepheid model II. Determination of stellar parameters and abundances
• Line-depth ratios as indicators of effective temperature and surface gravity
• The effect of surface gravity on line-depth ratios in the wavelength range 0.97-1.32 μm
• Atmospheric parameters of Cepheids from flux ratios with ATHOS: I. The temperature scale
• The flux-weighted gravity-luminosity relation of Galactic classical Cepheids
• CRIRES high-resolution infrared spectroscopy of the long-period Cepheid l Car

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• OCCASO V. Chemical-abundance trends with Galactocentric distance and age
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• Mapping radial abundance gradients with Gaia-ESO open clusters: Evidence of recent gas accretion in the Milky Way disk
• Metallicity estimation of MW, SMC and LMC classical Cepheids from the shape of the $V$- and $I$-band light curves
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• Spectral energy distributions of classical cepheids in the Magellanic Clouds
• Effective temperatures of classical Cepheids from line-depth ratios in the H-band
• Open clusters in the outer disc studied with MEGARA@GTC Auner 1 and Berkeley 102
• Forward-modelling Milky Way Cepheids: selection effects and physical priors in the Gaia-HST calibration