{
  "id": "1504.03349",
  "version": "v1",
  "published": "2015-04-13T20:14:08.000Z",
  "updated": "2015-04-13T20:14:08.000Z",
  "title": "Witnessing the Emergence of a Carbon Star",
  "authors": [
    "L. Guzman-Ramirez",
    "E. Lagadec",
    "R. Wesson",
    "A. A. Zijlstra",
    "A. Muller",
    "D. Jones",
    "H. M. J. Boffin",
    "G. C. Sloan",
    "M. P. Redman",
    "A. Smette",
    "A. I. Karakas",
    "Lars-Ake Nyman"
  ],
  "comment": "5 pages, 5 figures, accepted for publication in the Monthly Notices of the Royal Astronomical Society Letters",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "During the late stages of their evolution, Sun-like stars bring the products of nuclear burning to the surface. Most of the carbon in the Universe is believed to originate from stars with masses up to a few solar masses. Although there is a chemical dichotomy between oxygen-rich and carbon-rich evolved stars, the dredge-up itself has never been directly observed. In the last three decades, however, a few stars have been shown to display both carbon- and oxygen-rich material in their circumstellar envelopes. Two models have been proposed to explain this dual chemistry: one postulates that a recent dredge-up of carbon produced by nucleosynthesis inside the star during the Asymptotic Giant Branch changed the surface chemistry of the star. The other model postulates that oxygen-rich material exists in stable keplerian rotation around the central star. The two models make contradictory, testable, predictions on the location of the oxygen-rich material, either located further from the star than the carbon-rich gas, or very close to the star in a stable disk. Using the Faint Object InfraRed CAmera (FORCAST) instrument on board the Stratospheric Observatory for Infrared Astronomy (SOFIA) Telescope, we obtained images of the carbon-rich planetary nebula (PN) BD+30 3639 which trace both carbon-rich polycyclic aromatic hydrocarbons (PAHs) and oxygen-rich silicate dust. With the superior spectral coverage of SOFIA, and using a 3D photoionisation and dust radiative transfer model we prove that the O-rich material is distributed in a shell in the outer parts of the nebula, while the C-rich material is located in the inner parts of the nebula. These observations combined with the model, suggest a recent change in stellar surface composition for the double chemistry in this object. This is evidence for dredge-up occurring ~1000yr ago.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-04-13T20:14:08.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "carbon star",
      "oxygen-rich material",
      "carbon-rich polycyclic aromatic hydrocarbons",
      "superior spectral coverage",
      "faint object infrared camera"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}