{
  "id": "1511.03670",
  "version": "v1",
  "published": "2015-11-11T21:00:06.000Z",
  "updated": "2015-11-11T21:00:06.000Z",
  "title": "Gravity as the main driver of non-thermal motions in massive star formation",
  "authors": [
    "A. Traficante",
    "G. A. Fuller",
    "R. Smith",
    "N. Billot",
    "A. Duarte-Cabral",
    "N. Peretto",
    "S. Molinari",
    "J. E. Pineda"
  ],
  "comment": "Submitted to MNRAS. 11 pages, 7 figures",
  "categories": [
    "astro-ph.GA",
    "astro-ph.SR"
  ],
  "abstract": "The origin of non-thermal motions in massive star forming regions can be ascribed to turbulence acting against the gravitational collapse, or to the self-gravity itself driving the rapid global collapse. The dependence between velocity dispersion, radius and clouds surface density found by Heyer et al. (2009), $\\sigma/R^{1/2}\\propto \\Sigma^{1/2}$, has been interpreted in terms of global collapse of clouds. In this work we demonstrate that this relation is an expression of a more general relation between accelerations. We introduce the gravo-turbulent acceleration, a$_k$, which describe the non-thermal motions in each region, and the acceleration generated by the gravitational field a$_G$, which is proportional to $\\Sigma$. We also introduce a new coefficient, the force partition coefficient $\\alpha_{for}$ which is equivalent to the virial parameter but does not distinguish between collapsing and non-collapsing regions. In this work we use the a$_k$ - a$_G$ formalism in the analysis of a new sample of 16 massive starless clumps (MSCls) combined with data from the literature. We show that a$_k$ and a$_G$ are not independent. The non-thermal motions in each region can originate from both local turbulence and self-gravity but overall the data in the a$_k$ vs. a$_G$ diagram demonstrate that the majority of the non-thermal motions originate from self-gravity. We further show that all the MSCls with $\\Sigma\\geq 0.1$ g cm$^{-2}$ show signs of infall motions, a strong indication that the denser regions are the first to collapse. Finally, we include in the formalism the contribution of an external pressure and the magnetic fields.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-11-11T21:00:06.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "massive star formation",
      "main driver",
      "self-gravity",
      "rapid global collapse",
      "clouds surface density"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 11,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2015arXiv151103670T"
    }
  }
}