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The Red Rectangle
“Bizarro” Star?
OR
“Rosetta Stone”?
The Backdrop
Mysteries of Interstellar Chemistry
“Diffuse Interstellar Bands” (DIBs)
•Discovered in 1943 by
Paul Merrill
•300+ now known
•Positive ID for carrier
for only 2-3 lines
(maybe)!! Others
“possible”
“Unidentified Infrared Bands” (UIBs):
PAHs? HACs? QCCs?
The 2175 Å UV Extinction Band
The Story
Phase I - Era of Discovery
Discovery by Cohen + 15 (1975)
Extended Red Emission by Schmidt, Cohen & Margon (1980)
UV Bands by Sitko, Savage & Meade (1981)
Discovery by Cohen et al. 1975
Red Rectangle
Not
Blue Blob
UIBs
?????
“Extended Red
Emission”
Schmidt, Cohen
& Margon
(1980)
IUE Spectra
by SSM
(1981)
Unidentified
bands
between
1400-1800 Å
Organics or CO Fluorescence?
CO 4th Positive Absorption Bands: A1X1+
The IR
(“The GOOD”)
Waters et al. 1998 (ISO)
Mg2SiO4
UIBs
The Visible
(“The BAD”)
Red-degraded, Blue degraded and
Symmetric profiles
Fluorescence, Phosphorescence,
Inter-System Transitions
1 - fluorescence
2 - phosphorescence
3 - HPB in matrix
Related to DIBs?!
Van Winkel et al. (2002)
ERE band shapes:
2.9” (lowest)-5.6” (highest)
Approach (but not
always equal) DIB
wavelengths
The UV
(“The UGLY”)
“Blue
Luminescence”,
small PAHs, and
the UV cutoff Vijh, Witt &
Gordon (2005)
CO (0,0) and (1,0) 4th Positive (1996, unpub.)
T=3000 K
4-Component Model
Bob Glinski - TN Tech.
Cold Low-v Emission
Cold High-v Absorption
Cold Higher-v Emission
Hot Low-v Emission
Cameron Bands
Possible Source for Cameron Bands?
(c) HCO+ + e-  H + CO(a3Π,v’)
(more likely based on abundances)
(d) CO2+ + e-  CO(a3 Π,v’) + O
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Where is the CO Located?
4P is less polarized than the continuum
Cameron Bands & OH are essentially the same as continuum
OH
Emission
- UV pumped “cold fluorescence”
- “Prompt Emission” photodissociation of H2O
Larry Bernstein, Spectral Sciences, Inc.
Inventory
•Silicate dust (C/O < 1)
•Organic (PAH?) molecules (C/O > 1)
•ERE broad feature
•ERE narrow bands - related to DIBs?
•CO - 4th Positive, Cameron
•OH - Mixture of UV-pumped Cold OH and
Photodissociated H2O?
Interesting Curiosity:
Who else shows CO A1Π-X1Σ+, CO a3Π-X1Σ+, & OH A1Π-X1Σ+??
COMETS!
Photodestruction of the disk
(analogous to a Kuiper Belt/Oort Cloud
in the Red Rectangle?)
Interesting Aside:
UV photolysis of ice mixtures of
H2O, NH3, CH3OH, HCN (ISM and
comets) produces amino acids….
What About That Crazy Shape?
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It’s never really
THE END