Two jets from the Orion nebula (M42) 'proplyds': kinematics, morphologies and origins |
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| Authors: | J Meaburn M F Graham M P Redman |
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| Institution: | Jodrell Bank Observatory, Department of Physics &Astronomy, University of Manchester, Macclesfield, Cheshire SK11 9DL;Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BE |
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| Abstract: | A spatially unresolved velocity feature, with an approaching radial velocity of ≈100 km s−1 with respect to the systemic radial velocity, in a position–velocity array of O iii ] 5007-Å line profiles is identified as the kinematical counterpart of a jet from the proplyd LV 5 (158–323) in the core of the Orion nebula. The only candidate in Hubble Space Telescope ( HST ) imagery for this jet appears to be a displaced, ionized knot. Also an elongated jet projects from the proplyd GMR 15 (161–307). Its receding radial velocity difference appears at ≈80 km s−1 in the same position–velocity array.
A 'standard' model for jets from young, low-mass stars invokes an accelerating, continuous flow outwards with an opening angle of a few degrees. Here an alternative explanation is suggested which may apply to some, if not all, of the proplyd jets. In this, a 'bullet' of dense material is ejected which ploughs through dense circumstellar ambient gas. The decelerating tail of material ablated from the surface of the bullet would be indistinguishable from a continuously emitted jet in current observations. |
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| Keywords: | line: profiles stars: winds outflows ISM: individual: Orion nebula (M42) ISM: jets and outflows |
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