Cepheid Metallicity in the Leavitt Law (C- MetaLL) survey: II.High-resolution spectroscopy of the most metal poor Galactic Cepheids

Abstract

Classical Cepheids (DCEPs) are the first fundamental step in the calibration of the cosmological distance ladder. Furthermore, they represent powerful tracers in the context of Galactic studies. We have collected high-resolution spectroscopy with UVES@VLT for a sample of 65 DCEPs. The majority of them are the faintest DCEPs ever observed in the Milky Way. For each target, we derived accurate atmospheric parameters, radial velocities, and abundances for 24 different species. The resulting iron abundances range between +0.3 and $-$1.1 dex with the bulk of stars at [Fe/H]$\sim -0.5$ dex. Our sample includes the most metal-poor DCEPs observed so far with high-resolution spectroscopy. We complement our sample with literature data obtaining a complete sample of 637 DCEPs and use Gaia Early Data Release 3 (EDR3) photometry to determine the distance of the DCEPs from the Period-Wesenheit-Metallicity relation. Our more external data trace the Outer arm (at Galactocentric radius ($R_{GC})\sim$16--18 kpc) which appears significantly warped. We investigate the metallicity gradient of the Galactic disc using this large sample, finding a slope of $-0.060\pm 0.002$ dex kpc${}^{-1}$, in very good agreement with previous results based both on DCEPs and open clusters. We also report a possible break in the gradient at $R_{GC}$=9.25 kpc with slopes of $-0.063\pm 0.007$ and $-0.079\pm 0.003$ dex kpc${}^{-1}$ for the inner and outer sample, respectively. The two slopes differ by more than 1 $\sigma$. A more homogeneous and extended DCEPs sample is needed to further test the plausibility of such a break.

19 pages, 10 figures, accepted for publication on MNRAS

References in corpus (25)

• The Gaia mission
• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team
• Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM
• Cosmic Distances Calibrated to 1% Precision with Gaia EDR3 Parallaxes and Hubble Space Telescope Photometry of 75 Milky Way Cepheids Confirm Tension with LambdaCDM
• Measurements of the Hubble Constant: Tensions in Perspective
• On the Hubble constant tension in the SNe Ia Pantheon sample
• The mass distribution in the Galactic Centre from interferometric astrometry of multiple stellar orbits
• The influence of chemical composition on the properties of Cepheid stars. II-The iron content
• On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk
• The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy
• Galactic spiral structure revealed by Gaia EDR3
• The GALAH survey: tracing the Galactic disk with Open Clusters
• The AMBRE project: The thick thin disk and thin thick disk of the Milky Way
• Open clusters in APOGEE and GALAH: Combining Gaia and ground-based spectroscopic surveys
• Gaia Data Release 1 - The Cepheid & RR Lyrae star pipeline and its application to the south ecliptic pole region
• The influence of metallicity on the Leavitt Law from geometrical distances of Milky Way and Magellanic Clouds Cepheids
• Facing the problems on the determination of stellar temperatures and gravities: Galactic globular clusters
• 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
• Using classical Cepheids to study the far side of the Milky Way disk: I. Spectroscopic classification and the metallicity gradient
• On the Period--Luminosity--Metallicity relation of Classical Cepheids
• A new and homogeneous metallicity scale for Galactic classical Cepheids II. The abundance of iron and alpha elements
• Using classical Cepheids to study the far side of the Milky Way disk. II. The spiral structure in the first and fourth Galactic quadrants
• V363 Cas: a new lithium rich Galactic Cepheid
• HD344787: a true Polaris analogue?

Cited by in corpus (11)

• Oxygen, sulfur, and iron radial abundance gradients of classical Cepheids across the Galactic thin disk
• Cepheid metallicity in the Leavitt law (C-MetaLL) survey -- III. Simultaneous derivation of the Gaia parallax offset and Period-Luminosity-Metallicity coefficients
• Cepheid Metallicity in the Leavitt Law (C- MetaLL) survey: VI: Radial abundance gradients of 29 chemical species 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
• Period-Luminosity Relations for Galactic classical Cepheids in the Sloan bands
• The stellar evolution perspective on the metallicity dependence of classical Cepheid Leavitt laws
• Ultra Long Period Cepheids as standard candles from Gaia to Rubin-LSST
• Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey: IX. Metallicity dependence of Period-Wesenheit relations based on a homogeneous spectroscopic sample
• Exploring Low-Amplitude Variability in First Overtone Cepheids with TESS
• Cepheid Metallicity in the Leavitt Law (C--MetaLL) survey: VIII. High-Resolution IGRINS Spectroscopy of 23 Classical Cepheids: Validating NIR Abundances
• A hybrid SLAM-Payne framework for atmospheric parameter and abundance determination of early-type Stars from LAMOST DR9 low-resolution Spectra