Forming protostars in molecular clouds with shocked envelope expansion and core collapse

Authors

  • Yu-Qing Lou,

    Corresponding author
    1. Department of Physics and Tsinghua Centre for Astrophysics (THCA), Tsinghua University, Beijing 100084, China
    2. National Astronomical Observatories of China, Chinese Academy of Sciences, A20 Datun Road, Beijing 100012, China
    3. Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
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  • Yang Gao

    Corresponding author
    1. Department of Physics and Tsinghua Centre for Astrophysics (THCA), Tsinghua University, Beijing 100084, China
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E-mail: louyq@tsinghua.edu.cn (Y-QL); gaoyang-00@mails.tsinghua.edu.cn (YG)

ABSTRACT

Spectral observations of molecular line profiles reveal the so-called ‘blue profiles’ for double-peaked molecular spectral lines with stronger blue and weaker red peaks as notable features for star-forming cloud core collapses under the self-gravity. In contrast, ∼25–30 per cent of observed molecular spectral line profiles in star-forming clouds or cores also show the so-called double-peaked ‘red profiles’ with red peaks stronger than blue peaks. Gao & Lou show that these unexplained ‘red profiles’ can be signatures of global self-similar dynamics for envelope expansion with core collapse (EECC) within star-forming molecular clouds or cores. We demonstrate here that spatially resolved ‘red profiles’ of HCO+ (J= 1–0) and CS (J= 2–1) molecular transitions from the low-mass star-forming cloud core FeSt 1−457 together with its radial profile of column density inferred from dust extinction observations appear to reveal a self-similar hydrodynamic shock phase for global EECC. Observed spectral profiles of C18O (J= 1–0) are also fitted by the same EECC model. For further observational tests, the spatially resolved profiles of molecular transitions HCO+ (J= 3–2) and CS (J= 3–2) as well as the radial profiles of (sub)millimetre continuum emissions at three wavelengths of 1.2, 0.85 and 0.45 mm from FeSt 1−457 are also predicted.

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