FLIERs and other microstructures in planetary nebulae, 2

Balick, Bruce; Perinotto, M.; Maccioni, A.; Terzian, Yervant; Hajian, Arsen R.

doi:10.1086/173932

Cited by 117 publications

(143 citation statements)

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“…The parameters chosen for the cloudlet are within the observed parameter range of FLIERs (see, e.g., Balick et al 1994;Gonçalves 2007). The remainder of the computational domain is filled with a uniform, stationary medium of density n env = 100 cm −3 and temperature T env = 10 4 .…”

Section: The Numerical Simulationsmentioning

confidence: 99%

“…In (Riera et al 1995(Riera et al , 2006, triangles: M 1-92, M 2-56 and OH 238.1+4.2 (Trammell et al 1993;Sánchez Contreras et al 2000), stars: CRL 618 (Riera et al, in prep.)]. The red symbols correspond to ground-based spectroscopic data of NGC 6543 (circles), NGC 7009 (triangles) and IC 4634 (squares) are taken from Balick et al (1994), Gonçalves et al (2001), Guerrero et al (2008). Green symbols: synthesized spectra of different regions of NGC 6543, NGC 7009 and IC 4634 obtained from WFPC2 HST images (Lame et al 1997;.…”

Section: A Comparison With Observed Line Ratiosmentioning

confidence: 99%

“…Balick and coworkers explored the spectroscopic properties of FLIERs in a group of PNe (reported in a series of four papers: Balick et al 1993Balick et al , 1994Balick et al , 1998and Hajian et al 1997) and found that the physical conditions (electron density and temperature) in the high-velocity knots and jets are, in most cases, similar to the conditions in the surrounding nebula (see Gonçalves 2007, for a review of the physical conditions in microstructures of PNe). discussed the spectral features that separate FLIERs from shock-excited objects and "normal" photoionized regions.…”

Section: Introductionmentioning

confidence: 99%

“…Several models were developed to reproduce their main observational charateristics. FLIERs were modeled as ionization fronts, bowshocks (analogous to HH objects), and photo-evaporated clumps (Balick et al 1993(Balick et al , 1994Mellema et al 1998). FLIERs show unusual excitation conditions if these are identified with ionization fronts, apart from the fact that they move supersonically.…”

Section: Introductionmentioning

confidence: 99%

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Line ratios from shocked cloudlets in planetary nebulae

Raga

Riera

Mellema

et al. 2008

A&A

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Context. Some PNe and PPNe show compact knots, travelling at high velocities away from the central sources.Aims. We compute a number of models from which we obtain predictions of the emission-line spectrum, which can be compared with the spectra of the observed knots. Methods. We completed a series of 11 axisymmetric simulations of an initially spherical cloudlet, travelling away from a photoionizing source, into a uniform medium. The simulations included a multi-frequency transfer of the ionizing radiation, and a 33 species non-equilibrium ionization network. Results. From our simulations, we computed emission maps and spatially-integrated emission-line spectra. The predictions show a transition from spectra similar to those of shock wave models (for simulations with lower photoionization rates) to spectra similar to those of photoionized regions (for simulations with higher photoionization rates). Conclusions. The spectra from our photoionized cloudlet models have a range of line ratios that agree approximately with the observed spectra when shown in two-line ratio diagnostic diagrams. The predicted and observed spatial distributions of the emission (with high ionization lines extending more towards the source than lower ionization lines) agree in a qualitative way.

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Section: The Numerical Simulationsmentioning

confidence: 99%

Section: A Comparison With Observed Line Ratiosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Line ratios from shocked cloudlets in planetary nebulae

Raga

Riera

Mellema

et al. 2008

A&A

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“…In addition, some of these nebulae display small-scale features known as FLIERS, tails etc. (Balick 1987;Balick et al 1994). …”

Section: Introductionmentioning

confidence: 99%

The physical structure of the planetary nebula NGC 6781

Mavromatakis

Papamastorakis

Paleologou

2001

A&A

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Abstract. The planetary nebula NGC 6781 was imaged in major optical emission lines. These lines allow us to construct maps of the projected, two dimensional Balmer decrement, electron density, electron temperature, ionization and abundance structure. The average electron density, determined from the [S ii] lines, is ∼500 cm −3 , while the electron temperature distribution, determined from the [N ii] lines, is flat at ∼10 000 K. The Balmer decrement map shows that there are variations in extinction between the north and south areas of the planetary nebula. The higher extinction observed to the north of the central star is probably caused by dust spatially associated with CO emission at blue-shifted velocities. The [N ii] image reveals the known optical halo, at a flux level of ∼0.2% of the strong shell emission in the east, but now the angular extent of 216 ×190 is much larger than previous measurements. The halo is also present in [O iii], where we measure an extent of 190 ×162 . The ionization maps indicate substantial ionization along the caps of the ellipsoid as well as in the halo. The maps also show a sharp decrease in ionization along the outer edge of the shell in the west and the east, south-east. The typical log abundances measured for He, N, O and S are 10.97, 8.14, 8.72 and 6.90, respectively.

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Bipolar Outflows in Stellar Astrophysics

Frank

2002

Origin of Elements in the Solar System

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FLIERs and other microstructures in planetary nebulae, 2

Cited by 117 publications

References 0 publications

Line ratios from shocked cloudlets in planetary nebulae

Line ratios from shocked cloudlets in planetary nebulae

The physical structure of the planetary nebula NGC 6781

Bipolar Outflows in Stellar Astrophysics

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