Time‐dependent Accretion by Magnetic Young Stellar Objects as a Launching Mechanism for Stellar Jets

Goodson, Anthony P.; Winglee, R. M.; Bohm, Karl‐Heinz

doi:10.1086/304774

Cited by 226 publications

(259 citation statements)

References 30 publications

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“…These simulations corroborate a conceptual model laid out in Goodson, Winglee, & (1997), in which di †erential Bohm rotation between a central star and the surrounding accretion disk twists the stellar magnetic Ðeld. The twisted magnetic Ðeld expands because of helicity injection (in the presence of a thin conducting plasma).…”

Section: Introductionsupporting

confidence: 83%

“…The details of the oscillation mechanism are then derived, and the conclusion is reached that there are three possible classes of magnetically dominated axially symmetric accretion Ñow, with the average value of the magnetic di †usion in the disk making the physical distinction. The most di †usive Ñows have been described in detail by Ghosh & Lamb (1978, 1979a, 1979b, hereafter collectively GL), the intermediate-di †usivity Ñows by Lovelace, Romanova, & Bisnovatyi-Kogan (1995, hereafter LRBK), and the least di †usive Ñows by Goodson et al (1997) and in Paper I.…”

Section: Magnetospheric Oscillationsmentioning

confidence: 99%

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Jets from Accreting Magnetic Young Stellar Objects. II. Mechanism Physics

Goodson

Winglee

1999

ApJ

Self Cite

105

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This paper addresses the physical principles underpinning a new jet-launching mechanism described in a companion paper. In this new jet formation model, magnetic loops that connect the star to the disk become twisted and expand via helicity injection. This expansion drives an outÑow, with the axial symmetry of the disk leading to a concentration of outÑowing plasma along the rotation axis, forming the jet. In the companion paper, it is found that the radial location of the inner edge of the disk undergoes oscillations. In this paper, the physical causes of the disk oscillations are investigated. This investigation leads to the conclusion that there are three classes of Ñows that can arise, depending on the role of di †usive instabilities. The most di †usive Ñows allow the stellar magnetic Ðeld to slip through the accretion disk and yield steady accretion Ñows. Such conÐgurations are unlikely to produce outÑows. The Ñows with intermediate di †usivity have been described by Lovelace, Romanova, & Bisnovatyi-Kogan and represent conditions in which the Ðeld is e †ectively frozen into the accretion disk azimuthally but slips radially. In the absence of magnetic reconnection, such conÐgurations are predicted to produce steady Ñows with logarithmically collimated disk winds. The least di †usive Ñows, in which the bulk radial disk velocities are greater at times than the speeds with which magnetic Ðeld lines can di †use into the disks, lead to the formation of the collimated unsteady jets described in the companion paper and are the primary interest of this paper. The jet velocity is also addressed.

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Section: Introductionsupporting

confidence: 83%

Section: Magnetospheric Oscillationsmentioning

confidence: 99%

Jets from Accreting Magnetic Young Stellar Objects. II. Mechanism Physics

Goodson

Winglee

1999

ApJ

Self Cite

105

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“…One class of models predict that differential rotation leads to the expansion of the field lines, their opening and eventually their reconnection which restores the initial (assumed dipolar) magnetospheric configuration (e.g. Aly & Kuijpers 1990;Goodson et al 1997;Goodson & Winglee 1999). Magnetospheric inflation cycles are thus expected to develop and to be accompanied by violent episodic outflows as field lines open and reconnect as well as time dependent accretion rate onto the star (Hayashi et al 1996;Romanova et al 2002).…”

Section: Time Dependent Modelsmentioning

confidence: 99%

Magnetically Channeled Accretion in T Tauri Stars

Bouvier¹,

Alencar

Dougados³

2003

Open Issues in Local Star Formation

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“…Either centrifugal stresses or magnetic/thermal pressure are involved in the acceleration of the outflows, but it remains unclear which mechanism is dominant, whether it is universal, and how this mechanism acts when radiation pressure becomes significant as in Herbig Ae/Be stars. Numerical simulations predict temperatures between ∼10 000 K for the inner-disk winds up to ∼10 6 -10 7 K close to the magnetic reconnection boundary (Goodson et al, 1997). The X-rays (and the high-energy particles) produced in the reconnection areas will be redistributed towards lower energies due to the densities involved.…”

Section: Signatures Of Windsmentioning

confidence: 97%

“…During the last 5 years, numerical research on this interaction region has gone into outburst (see, e.g., Goodson et al, 1997Goodson et al, , 1999. So far, most studies have analysed the interaction between a dipolar stellar magnetic field and a Kepplerian accretion disk.…”

Section: The Physics Of Accretion and Outflowmentioning

confidence: 99%

UV Capabilities to Probe the Formation of Planetary Systems: From the ISM to Planets

Castro

Lecavelier

D’Avillez

et al.

Fundamental Questions in Astrophysics: Guidelines for Future UV Observatories

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Planetary systems are angular momentum reservoirs generated during star formation. Solutions to three of the most important problems in contemporary astrophysics are needed to understand the entire process of planetary system formation:The physics of the ISM. Stars form from dense molecular clouds that contain ∼30% of the total interstellar medium (ISM) mass. The structure, properties and lifetimes of molecular clouds are determined by the overall dynamics and evolution of a very complex system -the ISM. Understanding the physics of the ISM is of prime importance not only for Galactic but also for extragalactic and cosmological studies. Most of the ISM volume (∼65%) is filled with diffuse gas at temperatures between 3000 and 300 000 K, representing about 50% of the ISM mass. ing star formation, the so-called accretion-outflow engine. Elementary physical considerations show that, to be efficient, the acceleration region for the outflows must be located close to the star (within 1 AU) where the gravitational field is strong. According to recent numerical simulations, this is also the region where terrestrial planets could form after 1 Myr. One should keep in mind that today the only evidence for life in the Universe comes from a planet located in this inner disk region (at 1 AU) from its parent star. The temperature of the accretion-outflow engine is between 3000 and 10 7 K. After 1 Myr, during the classical T Tauri stage, extinction is small and the engine becomes naked and can be observed at ultraviolet wavelengths. The physics of planet formation. Observations of volatiles released by dust, planetesimals and comets provide an extremely powerful tool for determining the relative abundances of the vaporizing species and for studying the photochemical and physical processes acting in the inner parts of young planetary systems. This region is illuminated by the strong UV radiation field produced by the star and the accretion-outflow engine. Absorption spectroscopy provides the most sensitive tool for determining the properties of the circumstellar gas as well as the characteristics of the atmospheres of the inner planets transiting the stellar disk. UV radiation also pumps the electronic transitions of the most abundant molecules (H 2 , CO, etc.) that are observed in the UV.Here we argue that access to the UV spectral range is essential for making progress in this field, since the resonance lines of the most abundant atoms and ions at temperatures between 3000 and 300 000 K, together with the electronic transitions of the most abundant molecules (H 2 , CO, OH, CS, Springer 34 Astrophys Space Sci (2006) 303:33-52 S 2 , CO + 2 , C 2 , O 2 , O 3 , etc.) are at UV wavelengths. A powerful UV-optical instrument would provide an efficient mean for measuring the abundance of ozone in the atmosphere of the thousands of transiting planets expected to be detected by the next space missions (GAIA, Corot, Kepler, etc.). Thus, a follow-up UV mission would be optimal for identifying Earth-like candidates.

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Time‐dependent Accretion by Magnetic Young Stellar Objects as a Launching Mechanism for Stellar Jets

Cited by 226 publications

References 30 publications

Jets from Accreting Magnetic Young Stellar Objects. II. Mechanism Physics

Jets from Accreting Magnetic Young Stellar Objects. II. Mechanism Physics

Magnetically Channeled Accretion in T Tauri Stars

UV Capabilities to Probe the Formation of Planetary Systems: From the ISM to Planets

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