English  |  正體中文  |  简体中文  |  Items with full text/Total items : 54367/62174 (87%)
Visitors : 11236500      Online Users : 69
RC Version 6.0 © Powered By DSPACE, MIT. Enhanced by NTHU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version


    Please use this identifier to cite or link to this item: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/80965


    Title: AAS POSITION ON THE SPACE STATION
    Authors: SHU, F.;NAJITA, J.;OSTRIKER, E.;WILKIN, F.;RUDEN, S.;LIZANO, S.
    教師: 徐遐生
    Date: 1994
    Publisher: American Astronomical Society
    Relation: ASTROPHYSICAL JOURNAL, American Astronomical Society, Volume 429, Issue 2, Part 1, JUL 10 1994, Pages 781-796
    Keywords: ASTRONOMICAL MODELS
    CENTRIFUGAL FORCE
    DISK GALAXIES
    MAGNETIC FIELDS
    MASS FLOW
    PROTOSTARS
    STELLAR MASS ACCRETION
    T TAURI STARS
    ANGULAR MOMENTUM
    NUMERICAL ANALYSIS
    STELLAR WINDS
    TERMINAL VELOCITY
    Abstract: We propose a generalized model for stellar spin-down, disk accretion, and truncation, and the origin of winds, jets, and bipolar outflows from young stellar objects. We consider the steady state dynamics of accretion of matter from a viscous and imperfectly conducting disk onto a young star with a strong magnetic field. For an aligned stellar magnetosphere, shielding currents in the surface layers of the disk prevent stellar field lines from penetrating the disk everywhere except for a range of radii about omegaBAR = R(x), where the Keplerian angular speed of rotation OMEGA(x) equals the angular speed of the star OMEGA*. For the low disk accretion rates and high magnetic fields associated with typical T Tauri stars, R(x) exceeds the radius of the star R* by a factor of a few, and the inner disk is effectively truncated at a radius R(t) somewhat smaller than R(x). Where the closed field lines between R(t) and R(x) bow sufficiently inward, the accreting gas attaches itself to the field and is funneled dynamically down the effective potential (gravitational plus centrifugal) onto the star. Contrary to common belief, the accompanying magnetic torques associated with this accreting gas may transfer angular momentum mostly to the disk rather than to the star. Thus, the star can spin slowly as long as R(x) remains significantly greater than R*. Exterior to R(x) field lines threading the disk bow outward, which makes the gas off the midplane rotate at super-Keplerian velocities. This combination drives a magnetocentrifugal wind with a mass-loss rate M(w) equal to a definite fraction f of the disk accretion rate M(D). For high disk accretion rates, R(x) is forced down to the stellar surface, the star is spun to breakup, and the wind is generated in a manner identical to that proposed by Shu, Lizano, Ruden, & Najita in a previous communication to this journal. In two companion papers (II and III), we develop a detailed but idealized theory of the magnetocentrifugal acceleration process.
    Relation Link: http://aas.org/
    URI: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/80965
    Appears in Collections:[ 徐遐生 (2002-2006)] 期刊論文
    [物理系] 期刊論文

    Files in This Item:

    File SizeFormat
    62.pdf311KbAdobe PDF405View/Open


    在NTHUR中所有的資料項目都受到原著作權保護,僅提供學術研究及教育使用,敬請尊重著作權人之權益。若須利用於商業或營利,請先取得著作權人授權。
    若發現本網站收錄之內容有侵害著作權人權益之情事,請權利人通知本網站管理者(smluo@lib.nthu.edu.tw),管理者將立即採取移除該內容等補救措施。

    SFX Query

    與系統管理員聯絡

    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback