Vincent Icke's

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Vincent Icke's

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eMail: icke@strw.LeidenUniv.nl


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Background material for press release

Recent observations of the Red Rectangle, made with the Hubble Space Telescope, show exquisite detail of the outflow from the central double star. I predicted this double-cone pattern in the 1981 Astrophysical Journal. The development of extremely fast computers has enabled me to revisit this work. The computed flow patterns match the observations in great detail. I have written a popular account for all to read, and to enjoy! The attached page of links to Scientific Details goes into the subject more deeply.


Planetary Nebula Hydrodynamics:

Movies of Numerical Work

See the printed papers on my PN site, or browse in the electronic issues of Astronomy &Astrophysics. Caution Websurfers: these movies take quite a while to download! They are given in two formats: one low-quality at high compression, and one high quality that has about twice the size of the compressed version. For people with slower line connections, I have included a few movies of low-resolution simulations. All movies are in QuickTime format (Movie JPEG A-compression).

The Red Rectangle: Observations in H-band by Menschchikov et al.

I have a long-standing interest in this peculiar object; see

Are Bipolar Nebulae Biconical?, 1981 Astrophys.J. 247, 152

 

Currently, I am working on extracting realistic appearances from the hydro simulations shown below. This includes computing the appearance in reflected light, and the ionization structure (to apply to cases like this with hot central stars).

The Red Rectangle: Conical Outflow

In these computations, the fast-wind flow from the central star is supposed to be strongly focused by the reverse shock around the white dwarf. This causes `shock refraction', so that the flow leaves the central region in essentially a biconical shape. The inner regions cannot be resolved simultaneously with the outer flow without extreme computational expense. Therefore, the biconical flow is taken as given. The flow is pulsed, because Van Winckel's observations clearly indicate the presence of a train of shocks propagating outward. The computations were done with my FCT/LCD hydrocode on an Apple Macintosh G4.

Biconical Nebula Shaped by a Biconical Supersonic Outflow: B

Click to enlarge
Numerical computation of a pulsed biconical gas stream shooting into a homogeneous atmosphere. Grid size 120x240 cells, quadrupled. The flow is adiabatic with Poisson index 5/3 (monatomic gas). In this composite image, red indicates the density, green the temperature, and blue the velocity of the gas. The image is cylindrically symmetric about the horizontal axis. The dying star, which is now a young white dwarf, is in the centre of the image. You can download a medium quality movie (1.0 Mb) in QuickTime format.

Biconical Nebula Shaped by a Biconical Supersonic Outflow: B

Click to enlarge
Outflow model B (see above). In this composite image, red indicates the density, green the gas pressure, and blue the velocity of the gas. The image is cylindrically symmetric about the horizontal axis. The dying star, which is now a young white dwarf, is in the centre of the image. You can download a medium quality movie (1.2 Mb) in QuickTime format.

Biconical Nebula Shaped by a Biconical Supersonic Outflow: A

Click to enlarge
Numerical computation of a biconical gas stream shooting into a homogeneous atmosphere. Grid size 250x500 cells, quadrupled. The flow is adiabatic with Poisson index 1.1 (to simulate the effects of cooling by assuming high compressibility). In this composite image, red indicates the density, green the temperature, and blue the velocity of the gas. The image is cylindrically symmetric about the horizontal axis. The dying star, which is now a young white dwarf, is in the centre of the image. You can download a medium quality movie (3.3 Mb) in QuickTime format.

Biconical Nebula Shaped by a Biconical Supersonic Outflow: A

Click to enlarge
Outflow model A (see above). In this composite image, red indicates the density, green the gas pressure, and blue the velocity of the gas. The image is cylindrically symmetric about the horizontal axis. The dying star, which is now a young white dwarf, is in the centre of the image. You can download a medium quality movie (3.4 Mb) in QuickTime format.

Biconical Nebula Model A: Gas Density

Click to enlarge
Outflow model A (see above). This image shows the gas density: red indicates high values, and blue low. The image is cylindrically symmetric about the horizontal axis. The dying star, which is now a young white dwarf, is in the centre of the image. You can download a high quality movie (8.4 Mb) in QuickTime format.

Biconical Nebula Model A: Pressure

Click to enlarge
Outflow model A (see above). This image shows the gas pressure: red indicates high values, and blue low. The image is cylindrically symmetric about the horizontal axis. The dying star, which is now a young white dwarf, is in the centre of the image. You can download a high quality movie (9 Mb) in QuickTime format.

Biconical Nebula Model A: Temperature

Click to enlarge
Outflow model A (see above). This image shows the gas temperature: red indicates high values, and blue low. The image is cylindrically symmetric about the horizontal axis. The dying star, which is now a young white dwarf, is in the centre of the image. You can download a high quality movie (9 Mb) in QuickTime format.

Biconical Nebula Model A: Velocity

Click to enlarge
Outflow model A (see above). This image shows the gas velocity: red indicates high values, and blue low. The image is cylindrically symmetric about the horizontal axis. The dying star, which is now a young white dwarf, is in the centre of the image. You can download a high quality movie (8.1 Mb) in QuickTime format.

 


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