The Red Rectangle Nebula

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The Red Rectangle Nebula

• excited by excited species

Nadine Wehres, Claire Romanzin, Hans Van
Winckel, Harold Linnartz, Xander Tielens
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The Red Rectangle Nebula

• excited by excited species

Nadine Wehres, Claire Romanzin, Hans Van
Winckel, Harold Linnartz, Xander Tielens
identify molecules in space and laboratory ?
constraining physical and chemical conditions in
RR
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identify molecules in space and laboratory ?
constraining physical and chemical conditions in
RR
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Outline

• The Red Rectangle proto-planetary nebula
• The observations
• The laboratory experiments
• Simulations
• Conclusion

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The Red Rectangle Nebula
Van Winckel et al., AA, 2002, 390, 147
The post AGB star shows episodic mass loss that
still enriches the surrounding nebula and is a
great laboratory for ongoing molecule formation
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The optical emission features of the Red Rectangle
Extended Red Emission and molecular bands solid
state species and gas phase molecules
Van Winckel et al., AA, 2002, 390, 147
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Molecules in the Red Rectangle

• Small molecules have been identified
• 12CO 13CO CO2 OH CH CH CN
• Larger species have not been identified sofar,
  however
• Typical PAH emission features are observed
• 3.3 6.2 7.7 8.6 and 11.3 µm
• Silicate emission features

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New Technology Telescope, La Silla, Chile
Obtain complete and medium resolution data-set of
spectral progression with distance from central
star
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Observations of the Red Rectangle emission
features Using the New Technology Telescope at
La Silla, Chile
Very faint object long slit spectroscopy for
better S/N Measurements performed for Central
Star 3 6 7 11 14 16 and 20
Van Winckel et al., AA, 2002, 390, 147
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Laser Induced Fluorescence Spectroscopy Search
for Carriers

• Open Questions
• What is causing the observed features ?
• Can we simulate the Red Rectangle in the
  laboratory?
• Can we conclude on the actual physical
  conditions?

• Emission Spectroscopy vs.
• Absorption Spectroscopy

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Discharge Source expanding acetylene (C2H2)
plasma

• - Carbon radicals
• - Transient species
• Ions and radicals
• - Rovibronically excited
• species
• Nevertheless,
• rotationally cold species
• because of adiabatic
• expansion

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C2 Swan-Band transitions
d3pg (v1) a3pu (v2)
d3pg (v0) a3pu (v1)
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Peak Positions
C2?
C2?
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Simulations Rotational contour fitting routines
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Simulations Rotational contour fitting routines
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Simulations Rotational contour fitting routines
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Conclusions

• Unambiguous identification of excited C2 in the
  Red Rectangle at several distances in the
  outflows (at 3, 6 and 7)
• Corresponding with Swan band transitions
• d3pg a3pu (v,v) (1,0) and (2,1)
• Rotational contour simulations show a temperature
  of about 550 /- 200 K in the nebula at closer
  distances

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Work in progress

• CH has been identified Trot of only 120 K
  50 K
• (Hall et al. (1992), Nature, Vol 358)
• ? Why is C2 warmer a chemical reason ?
• statistical equilibrium equations (radiative
  transfer mechanism) of the excitation pathways of
  C2
• Formation and destruction scheme of C2
• Spectral dynamics of other observed bands as
  function of the distance to the central star.
• and as emission probe for absorption features

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Seen in interstellar clouds towards reddened stars
DIBs
Sarre et al., Science 1995, 269, 674
Red Rectangle
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Thank you for your Attention