{
  "id": "0911.2470",
  "version": "v1",
  "published": "2009-11-13T17:46:33.000Z",
  "updated": "2009-11-13T17:46:33.000Z",
  "title": "Galactic Cepheids with Spitzer: I. Leavitt Law and Colors",
  "authors": [
    "M. Marengo",
    "N. R. Evans",
    "P. Barmby",
    "G. Bono",
    "D. L. Welch",
    "M. Romaniello"
  ],
  "comment": "Accepted by The Astrophysical Journal on Nov 11, 2009",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "Classical Cepheid variable stars have been important indicators of extragalactic distance and Galactic evolution for over a century. The Spitzer Space Telescope has opened the possibility of extending the study of Cepheids into the mid- and far-infrared, where interstellar extinction is reduced. We have obtained photometry from images of a sample of Galactic Cepheids with the IRAC and MIPS instruments on Spitzer. Here we present the first mid-infrared period-luminosity relations for Classical Cepheids in the Galaxy, and the first ever Cepheid period-luminosity relations at 24 and 70 um. We compare these relations with theoretical predictions, and with period-luminosity relations obtained in recent studies of the Large Magellanic Cloud. We find a significant period-color relation for the [3.6]-[8.0] IRAC color. Other mid-infrared colors for both Cepheids and non-variable supergiants are strongly affected by variable molecular spectral features, in particular deep CO absorption bands. We do not find strong evidence for mid-infrared excess caused by warm (~500 K) circumstellar dust. We discuss the possibility that recent detections with near-infrared interferometers of circumstellar shells around delta Cep, l Car, Polaris, Y Oph and RS Pup may be a signature of shocked gas emission in a dust-poor wind associated to pulsation-driven mass loss.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-11-13T17:46:33.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "galactic cepheids",
      "leavitt law",
      "variable molecular spectral features",
      "classical cepheid",
      "pulsation-driven mass loss"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-637X/709/1/120",
      "journal": "The Astrophysical Journal",
      "year": 2010,
      "month": "Jan",
      "volume": 709,
      "number": 1,
      "pages": 120
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 836819,
      "adsabs": "2010ApJ...709..120M"
    }
  }
}