Home | Contact us | Staff | Students | MyExeter (Staff) | exehub (Students) | Site map |

      StudyingResearchBusiness and communityWorking hereAlumni and supportersOur departmentsVisiting usAbout us

      Open Research Exeter (ORE)

      View Item 
      •   ORE Home
      • College of Engineering, Mathematics and Physical Sciences
      • Physics
      • View Item
      •   ORE Home
      • College of Engineering, Mathematics and Physical Sciences
      • Physics
      • View Item
      JavaScript is disabled for your browser. Some features of this site may not work without it.

      Accretion-powered stellar winds. III. spin-equilibrium solutions

      Thumbnail
      View/Open
      Matt2008The Astrophysical Journal-1.pdf (242.2Kb)
      Date
      2008-07-01
      Author
      Matt, Sean P.
      Pudritz, Ralph E.,
      Date issued
      2008-07-01
      Journal
      Astrophysical Journal
      Type
      Article
      Language
      en
      Publisher
      Institute of Physics (IOP) Publishing
      Rights
      © 2008. The American Astronomical Society. All rights reserved.
      Abstract
      We compare the stellar wind torque calculated in a previous work (Paper II) to the spin-up and spin-down torques expected to arise from the magnetic interaction between a slowly rotating (∼10% of breakup) pre-main-sequence star and its accretion disk. This analysis demonstrates that stellar winds can carry off orders of magnitude more angular momentum than can be transferred to the disk, provided that the mass outflow rates are substantially greater than the solar wind. Thus, the equilibrium spin state is simply characterized by a balance between the angular momentum deposited by accretion and that extracted by a stellar wind. We derive a semianalytic formula for predicting the equilibrium spin rate as a function only of the ratio of Ṁw/ Ṁa and a dimensionless magnetization parameter, Ψ ≡ B2*R2*(Ṁavesc) -1, where Ṁw is the stellar wind mass outflow rate, Ṁa is the accretion rate, B* is the stellar surface magnetic field strength, R* is the stellar radius, and vesc is the surface escape speed. For parameters typical of accreting pre-main-sequence stars, this explains spin rates of ∼10% of breakup speed for Ṁw/Ṁa ∼ 0.1. Finally, the assumption that the stellar wind is driven by a fraction of the accretion power leads to an upper limit to the mass flow ratio of Ṁw/Ṁ a≲0.6. © 2008. The American Astronomical Society. All rights reserved.
      Funders/Sponsor
      National Science Foundation (NSF)
      Frank Levinson Family Foundation
      Peninsula Community Foundation
      Natural Sciences and Engineering Research Council of Canada (NSERC)
      Description
      Final published version of article. Also available from the publisher via: http://dx.doi.org/10.1086/587453
      Citation
      Vol. 681, pp. 391 - 399
      Grant number
      PHY05-51164
      DOI
      https://doi.org/10.1086/587453
      URI
      http://hdl.handle.net/10871/19356
      ISSN
      0004-637X
      Collections
      • Physics

      Using our site |  Freedom of Information |  Data Protection |  Copyright & disclaimer |  Privacy & Cookies | 

       

       

      Related Links
      What is ORE Library Site Research Site
      Browse
      All of ORECommunities & CollectionsTitlesAuthorsTypeThis CollectionTitlesAuthorsType
      Statistics
      Most Popular ItemsStatistics by Country

      Using our site |  Freedom of Information |  Data Protection |  Copyright & disclaimer |  Privacy & Cookies |