Which jet launching mechanism(s) in T Tauri stars

By J. Ferreira, C. Dougados, S. Cabrit. 2006

301 citations recorded by the source corpus.

Aims. We examine whether ejection phenomena from accreting T Tauri stars can be described by only one type of self-collimated jet model. Methods. We present analytical kinematic predictions valid soon after the Alfven surface for all types of steady magnetically s elf-confined jets. Results. We show that extended disc winds, X-winds, and stellar winds occupy distinct regions in the poloidal speed vs. specific an gular momentum plane. Comparisons with current observations of T Tauri jets yield quantitative constraints on the range of la unching radii, magnetic lever arms, and specific energy input in disc and stellar wind s. Implications on the origin of jet asymmetries and disc magnetic fields are outlined. Conclusions. We argue that ejection phenomena from accreting T Tauri stars most likely include three dynamical components: (1) an outer self-collimated steady disc wind carrying most of the mass-flux in the optical jet (when present), confining (2) a pressur e-driven coronal stellar wind and (3) a hot inner flow made of blobs sporadically ejecte d from the magnetopause. If the stellar magnetic moment is parallel to the disc magnetic field, then the highly variable inner flow resem bles a "Reconnection X-wind", that has been proven to effi ciently brake down an accreting and contracting young star. If the magnetic moment is anti-parallel, then larger versions of the solar coro nal mass ejections are likely to occur. The relative importance of these three components in the observed outflows and the range of radii involve d in the disc wind are expected to vary with time, from the stage of embedded source to the optically revealed T Tauri star phase.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/b4247b21e70d569138165cf07fcc1bbf5df30265

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Citations in the corpus

MHD simulations of jet acceleration from Keplerian accretion disks - The effects of disk resistivity (2007, background): “…underlying accretion disk can support the magnetic structure and provide the mass load imposed as a boundary condition by the authors; on the other hand, it has been shown (Ferreira et al. 2006) that “X-winds” have kinematic properties that are inconsistent with observations of T Tauri microjets.”
Launching of conical winds and axial jets from the disc–magnetosphere boundary: axisymmetric and 3D simulations (2009, background): “Conical winds may be further collimated at larger distances from the star either by the pressure of the external medium (Lovelace et al. 1991; Frank & Mellema 1996), or by disc winds (Königl & Pudritz 2000; Ferreira et al. 2006; Matsakos et al. 2008; Fendt 2009).”
Accretion-powered Stellar Winds. II. Numerical Solutions for Stellar Wind Torques (2008, background): “…(Königl & Pudritz 2000), the X-ray luminosities (Decampli 1981), and possible detection of rotation (Bacciotti et al. 2002; Anderson et al. 2003; Coffey et al. 2004; Ferreira et al. 2006; Coffey et al. 2007), it appears that most of the flow arises from the accretion disk, rather than the star.”
THE INTERPLAY OF MAGNETIC FIELDS, FRAGMENTATION, AND IONIZATION FEEDBACK IN HIGH-MASS STAR FORMATION (2010, background): “Controversy persists about the exact mechanism driving them (Ferreira et al. 2006), with viable suggestions including disk winds (Blandford & Payne 1982; Königl & Pudritz 2000), tower flows produced by wound up toroidal field (Tomisaka 1998, 2002; Matsumoto & Tomisaka 2004; Machida et al. 2004;…”
Accretion onto Pre-Main-Sequence Stars (2016, background): “In the standard picture, the winds and jets are driven by rotating magnetic fields anchored somewhere in the inner disk (see the discussion in Section 3.2), although launching by other mechanisms can be important (Ferreira et al. 2006).”
MHD simulations of accretion onto a dipolar magnetosphere - II. Magnetospheric ejections and stellar spin-down (2012, background): “Indeed, such a high ejection efficiency presents a serious energetic problem (Ferreira et al. 2006): since CTTS are slow rotators and their centrifugal push is not strong enough to drive these outflows, an extra energy input is required.”