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Title: THE SHAPING OF THE MULTIPOLAR PRE-PLANETARY NEBULA CRL 618 BY MULTIDIRECTIONAL BULLETS

In order to understand the formation of the multipolar structures of the pre-planetary nebula CRL 618, we perform 3D simulations using a multidirectional bullet model. The optical lobes of CRL 618 and fast molecular outflows at the tips of the lobes have been found to have similar expansion ages of ∼100 yr. Additional fast molecular outflows were found near the source along the outflow axes with ages of ∼45 yr, suggesting a second episode of bullet ejections. Thus, in our simulations, two episodes of bullet ejections are assumed. The shaping process is simulated using the ZEUS-3D hydrodynamics code that includes molecular and atomic cooling. In addition, molecular chemistry is also included to calculate the CO intensity maps. Our results show the following: (1) Multiepoch bullets interacting with the toroidal dense core can produce the collimated multiple lobes as seen in CRL 618. The total mass of the bullets is ∼0.034 M{sub ⊙}, consistent with the observed high-velocity (HV) CO emission in fast molecular outflows. (2) The simulated CO J = 3–2 intensity maps show that the low-velocity cavity wall and the HV outflows along the lobes are reasonably consistent with the observations. The position–velocity diagram of the outflows along the outflow axesmore » shows a linear increase of velocity with distance, similar to the observations. The ejections of these bullets could be due to magnetorotational explosions or nova-like explosions around a binary companion.« less
Authors:
; ;  [1] ;  [2]
  1. Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China)
  2. Centre for Astrophysics and Space Science, University of Kent, Canterbury CT2 7NH (United Kingdom)
Publication Date:
OSTI Identifier:
22518534
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 820; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; COMPUTERIZED SIMULATION; DIAGRAMS; DISTANCE; HYDRODYNAMICS; MASS TRANSFER; PLANETARY NEBULAE; STARS; STELLAR WINDS; VELOCITY; Z CODES