{
  "id": "1807.06017",
  "version": "v1",
  "published": "2018-07-16T18:00:01.000Z",
  "updated": "2018-07-16T18:00:01.000Z",
  "title": "Chemo-kinematic ages of eccentric-planet-hosting M dwarf stars",
  "authors": [
    "Mark J. Veyette",
    "Philip S. Muirhead"
  ],
  "comment": "accepted for publication in ApJ",
  "categories": [
    "astro-ph.SR",
    "astro-ph.EP"
  ],
  "abstract": "M dwarf stars are exciting targets for exoplanet investigations; however, their fundamental stellar properties are difficult to measure. Perhaps the most challenging property to measure is stellar age. Once on the main sequence, M dwarfs change imperceptibly in their temperature and luminosity, necessitating novel statistical techniques for estimating their ages. In this paper, we infer ages for known eccentric-planet-hosting M dwarfs using a combination of kinematics and $\\alpha$-element-enrichment, both shown to correlate with age for Sun-like FGK stars. We calibrate our method on FGK stars in a Bayesian context. To measure $\\alpha$-enrichment, we use publicly-available spectra from the CARMENES exoplanet survey and a recently developed [Ti/Fe] calibration utilizing individual Ti I and Fe I absorption lines in $Y$ band. Tidal effects are expected to circularize the orbits of short-period planets on short timescales; however, we find a number of mildly eccentric, close-in planets orbiting old ($\\sim$8 Gyr) stars. For these systems, we use our ages to constrain the tidal dissipation parameter of the planets, $Q_\\mathrm{p}$. For two mini-Neptune planets, GJ 176b and GJ 536b, we find they have $Q_\\mathrm{p}$ values more similar to the ice giants than the terrestrial planets in our Solar System. For GJ 436b, we estimate an age of $8.9^{+2.3}_{-2.1}$ Gyr and constrain the $Q_\\mathrm{p}$ to be $>10^5$, in good agreement with constraints from its inferred tidal heating. We find that GJ 876d has likely undergone significant orbital evolution over its $8.4^{+2.2}_{-2.0}$ Gyr lifetime, potentially influenced by its three outer companions which orbit in a Laplace resonance.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-07-16T18:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "dwarf stars",
      "chemo-kinematic ages",
      "undergone significant orbital evolution",
      "fgk stars",
      "tidal dissipation parameter"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}