{
  "id": "1703.07031",
  "version": "v1",
  "published": "2017-03-21T02:53:52.000Z",
  "updated": "2017-03-21T02:53:52.000Z",
  "title": "Rotation of Late-Type Stars in Praesepe with K2",
  "authors": [
    "L. M. Rebull",
    "J. R. Stauffer",
    "L. A. Hillenbrand",
    "A. M. Cody",
    "J. Bouvier",
    "D. R. Soderblom",
    "M. Pinsonneault",
    "L. Hebb"
  ],
  "comment": "Accepted by ApJ",
  "categories": [
    "astro-ph.SR"
  ],
  "abstract": "We have Fourier analyzed 941 K2 light curves of likely members of Praesepe, measuring periods for 86% and increasing the number of rotation periods (P) by nearly a factor of four. The distribution of P vs. (V-K), a mass proxy, has three different regimes: (V-K)<1.3, where the rotation rate rapidly slows as mass decreases; 1.3<(V-K)<4.5, where the rotation rate slows more gradually as mass decreases; and (V-K)>4.5, where the rotation rate rapidly increases as mass decreases. In this last regime, there is a bimodal distribution of periods, with few between $\\sim$2 and $\\sim$10 days. We interpret this to mean that once M stars start to slow down, they do so rapidly. The K2 period-color distribution in Praesepe ($\\sim$790 Myr) is much different than in the Pleiades ($\\sim$125 Myr) for late F, G, K, and early-M stars; the overall distribution moves to longer periods, and is better described by 2 line segments. For mid-M stars, the relationship has similarly broad scatter, and is steeper in Praesepe. The diversity of lightcurves and of periodogram types is similar in the two clusters; about a quarter of the periodic stars in both clusters have multiple significant periods. Multi-periodic stars dominate among the higher masses, starting at a bluer color in Praesepe ((V-K)$\\sim$1.5) than in the Pleiades ((V-K)$\\sim$2.6). In Praesepe, there are relatively more light curves that have two widely separated periods, $\\Delta P >$6 days. Some of these could be examples of M star binaries where one star has spun down but the other has not.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-03-21T02:53:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "late-type stars",
      "multi-periodic stars dominate",
      "rotation rate rapidly increases",
      "multiple significant periods",
      "k2 period-color distribution"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}