Evolution of PAH features from proto-PN to planetary nebulae

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Evolution of PAH features from proto-PN to
planetary nebulae

• Ryszard Szczerba
• N. Copernicus Astronomical Center
• Torun, Poland

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Collaborators
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• Mirek Schmidt (CAMK)
• Natasza Siódmiak (CAMK)
• Grazyna Stasinska (LUTH Obs. Paris-Meudon)
• Cezary Szyszka (UMK)

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Sir Frederick William Herschel
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• F.W. Herschel (1738 -1822) was born in Hanover.
• From 1757 he lived in England.
• A musician and an astronomer.
• In 1781 he discovered Uranus
• He created catalogs of double stars and nebulae
• In 1800 he discovered infrared radiation.....

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Discovery of IR radiation.
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Dust -
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• INTRODUCTION
• Existence of solid particles was demonstrated by
  Trumpler (1930) through the measurements of color
  excess between the photographic (4300 A) and V
  (5500 A) magnitudes.
• By the end of 30s, a l-1 extinction law in the
  wavelength range 1-3 mm-1 had been established.
• Greenstein (1938) proposed a power-law size
  distribution of dust grains (dn(a)/da a-3.6!)
  in the size range 80Altalt1 cm to explain the l-1
  extinction law.
• The discovery of interstellar polarization
  stimulated Cayrel Schatzman (1954) to consider
  graphite as interstellar dust component (strong
  optical anisotropy).

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Extinction law
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RA(V)/E(B-V)
N(H)/E(B-V)5.8 1021 cm-2 (Bohlin et al. 1978)
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graphitic structure
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Graphite is highly anisotropic material
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Dust -
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• INTRODUCTION cont.
• Hoyle Wickramasinghe (1962) proposed that
  graphite could form in the atmospheres of cool
  C-stars and be ejected into ISM.
• In 1960s and early 1970s UV space missions
  allowed to determine extinction law in the
  wavelength range 0.2-10 mm-1.
• The presence of 2200 A interstellar extinction
  bump (Stecher 1965) was interpreted as
  reinforcement of the graphite proposal. However,
  exact nature of this bump still remains
  unidentified!
• Gilman (1969) proposed that grains around M-type
  stars are mainly silicates (Al2SiO3, Mg2SiO4,
  ...).
• Interstellar silicates were first detected in
  emission in Orion Nebula (Stein Gillett 1969)
  and in absorption toward the Galactic Center
  (Hackwell et al. 1970).

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amorphous silicate features
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9.7 mm Si-O stretching mode 18 mm O-Si-O bending
mode
Dust thermal emission lmm x TK 3000 ISM
T20 K lmax150 mm CS T150 K lmax20 mm
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Dust -
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• INTRODUCTION cont.
• In mid-1970s the interstellar extinction curve
  had been determined in the whole wavelengths
  range the main dust components had been
  determined (graphite silicates).
• Mathis et al. (1977) proposed a model of
  interstellar dust composed of silicates and
  graphite with grain size distribution dn(a)/da
  a-3.5 in the size range 50 A lt a lt 0.25 mm (MRN
  model)
• MRN model is very successful 1250 citations in
  ADS (56 in 2005).

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MRN model of interstellar dust
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• Silicates graphite
• dn(a)/da a-3.5
• 50Altalt0.25 mm

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Dust -
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• Very Small Grains (VSGs)
• Donn (1968) proposed that particles like
  Policyclic Aromatic Hydrocarbons (PAHs) may be
  responsible for the UV interstellar extinction.
• Greenberg (1968) first pointed out that VSGs with
  a heat content comparable to the energy of a
  single photon, cannot be characterized by an
  equilibrium temperature but are subject to
  fluctuations in temperature.
• Observational arguments that VSGs are present in
  Interstellar Space

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VSGs in Inter- CS-stellar Space
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1. The discovery of presolar nanodiamonds (Lewis et
   al. 1987) and TiC nanocrystals (Bernatowicz et
   al. 1996).
2. The ubiquitous distinctive set of UIR emission
   bands _at_ 3.3, 6.2, 7.7, 8.6 and 11.3 mm (UIR
   bands were discoverd first by Gillet et al.
   (1973) in planetary nebulae). This emission can
   be explained by transiently heating PAHs (e.g
   model of Li Draine 2001 for ISM, where UIRs
   account 20 of the total power radiated by
   dust).
3. The mid-IR emission at llt60 mm, discovered by
   IRAS (12 25 mm bands) and confirmed by
   COBE-DIRBE and IRTS observations (see e.g. Draine
   2003 and references therein). This emission can
   be explained also by transiently heating PAHs
   (Weingartner Draine 2001).

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Presolar grains from meteorites
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Presolar grains
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typical dust particle (top) Presolar SiC
(right)
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PAH features in
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reflection nebulae
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PAHs aromatic rings H
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• Leger Puget (1984)
• Allamandola et al. (1989)
• C-H stretch _at_ 3.3 mm
• C-C stretch _at_ 6.2 mm
• C-C stretch _at_ 7.7 mm
• C-H in-plane bend _at_ 8.6 mm
• C-H out of plane bend _at_ 11.3 mm for mono H
• _at_ 12.0 mm for duo H
• _at_ 12.7 mm for trio H
• _at_ 13.6 mm for quartet H
• aliphatic (chain-like) C-H stretch _at_ 3.4 mm

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graphitic structure
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Graphite is highly anisotropic material
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PAH features in
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galaxies (top) HII regions (right)
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PAH features in
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WR planetary nebulae Szczerba et al. (2001)
The detection by ISO ofcrystalline silicates
marks begining of ASTROCRYSTALOGRAPHY
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The mid-IR emission at llt60mm
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Observed (left) Model (bottom) Weigartner
Draine (2001)
For T15-25 K, emission from large grains is
lower by several orders of magnitude!
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VSGs in Inter- CS-stellar Space
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1. The far-UV extinction rise (Donn 1968 see also
   Kruegel 2003). Dust grains absorbs and scatters
   light most effectively _at_l2pa.
2. The anomalous Galactic foreground microwave
   emission in th 10-100 GHz region. Discovered
   during studies of CMB is probably due to the fats
   rotation fo nanoparticles (Draine Lazarian
   1998).
3. The Extended Red Emission (ERE), first discovered
   in Red Rectangle (Schmidt et al. 1980). The ERE
   is attributed to PL of (possibly?) crystalline
   nano-silicon clusters (Witt et al. 1998).
4. The photoelectric heating of the diffuse ISM.
   VSGs are more efficient in heating the gas than
   large grains. VSGs are responsible for gt 95 of
   the total photoelectric heating of the gas in ISM
   (Weingartner Draine 2001) .

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PAHs in LMC Ciska Markwick-Kemper et al.
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PAHs in LMC
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3.3 3.4 mm bands in PN BD 30 3639
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7.7 8.6 mm bands in PN BD 30 3639
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6.2, 7.7 8.6 mm bands in PN BD 30 3639
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7.7 mm band shape in proto-PN
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6.2 mm band shape in galactic objects
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3.3 mm C-H stretching mode
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6.2 mm C-C stretching mode
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7.7 mm C-C stretching mode
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Ratio of 7.7 an 6.2 mm bands
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8.6 mm C-H in-plane bending mode
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Correlation between 3.3 6.2 mm bands
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Correlation between 7.7 8.6 mm bands
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3.3 mm band in proto-PN
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6.2 mm band in proto-PN
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7.7 mm band in proto-PN
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8.6 mm band in proto-PN
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• Stasinska, Szczerba, Schmidt, Siódmiak
• Post-AGB objects as testbeds of nuclosynthesis
  in AGB stars
• submitted to AA
• We can investigate chemistry in objects with
  smaller mass
• C smaller uncertainty than in PNe
• ....

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CNO in post-AGB objects
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CNO in post-AGB objects
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