{
  "id": "2008.04608",
  "version": "v1",
  "published": "2020-08-11T10:04:34.000Z",
  "updated": "2020-08-11T10:04:34.000Z",
  "title": "On the Period--Luminosity--Metallicity relation of Classical Cepheids",
  "authors": [
    "V. Ripepi",
    "G. Catanzaro",
    "R. Molinaro",
    "M. Marconi",
    "G. Clementini",
    "F. Cusano",
    "G. De Somma",
    "S. Leccia",
    "I. Musella",
    "V. Testa"
  ],
  "comment": "7 pages, 4 figures. Accepted for publication on Astronomy and Astrophysics",
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA"
  ],
  "abstract": "Classical Cepheids (DCEPs) are the most important primary indicators for the extragalactic distance scale. Establishing the dependence on metallicity of their period--luminosity and period--Wesenheit (PL/PW) relations has deep consequences on the estimate of the Hubble constant (H$_0$). We aim at investigating the dependence on metal abundance ([Fe/H]) of the PL/PW relations for Galactic DCEPs. We combined proprietary and literature photometric and spectroscopic data, gathering a total sample of 413 Galactic DCEPs (372 fundamental mode -- DCEP\\_F and 41 first overtone -- DCEP\\_1O) and constructed new metallicity-dependent PL/PW relations in the near infra-red (NIR) adopting the Astrometric Based Luminosity. We find indications that the slopes of the PL$(K_S)$ and PW$(J,K_S)$ relations for Galactic DCEPs might depend on metallicity when compared to the Large Magellanic Cloud relationships. Therefore, we have used a generalized form of the PL/PW relations to simultaneously take into account the metallicity dependence of the slope and intercept of these relations. We calculated PL/PW relations which, for the first time, explicitly include a metallicity dependence of both the slope and intercept terms. Although the insufficient quality of the available data makes our results not yet conclusive, they are relevant from a methodological point of view. The new relations are linked to the geometric measurement of the distance to the Large Magellanic Cloud and allowed us to estimate a {\\it Gaia} DR2 parallax zero point offset $\\Delta \\varpi$=0.0615$\\pm$0.004 mas from the dataset of DCEPs used in this work.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-08-11T10:04:34.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "classical cepheids",
      "period-luminosity-metallicity relation",
      "galactic dceps",
      "dr2 parallax zero point offset",
      "metallicity dependence"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}