Post on 22-Dec-2015
HD 204827, the C2, C3 rich sightline
The C2 Diffuse Interstellar Bands
Takeshi Oka
Department of Astronomy and AstrophysicsAnd Department of Chemistry
The Enrico Fermi Institute, University of Chicago
J. A. Thorburn, L. M. Hobbs, T. Oka, D. E. Welty, D. G. York B. J. McCall, S. D. Friedman, P. Sonnentrucker, T. P. Snow
ApJ 584, 339-356 (2003)
Carbon in space, Lago di Como, May 23, 2006
T. Oka, Thorburn, J. A., McCall, B. J., S. D. Friedman,L. M. Hobbs, P.Sonnentrucker, D. E. Welty, D. G. York
ApJ 582, 823-829 (2003)
HD 204827, the C2, C3 rich sightline
William Huggins, Comet Tebbutt, 1881
1942
1951 Alex Douglas C3
1966 IVR The Douglas effect
1975 HCCCCCN,
1977-8 HCCCCCCCN, HCCCCCCCCCN
Origin of diffuse interstellar linesNature, 269 130 (1977) Alex Douglas
Cn
Proc. R. Soc. London, A. 34, 148 (1881)4050 Å
• J. A. Thorburn, L. M. Hobbs, T. Oka, D. E. Welty, D. G. York, B. J. McCall, S. D. Friedman, P. Sonnentrucker, T. P. Snow
• Apache Point Observatory 3.5-meter• 3,800–10,000 Å ; / ~ 38,000 (8 km/s)• 53 stars, 0.11<E(B-V)<1.99, S/N > 800 at 5780 Å
Systematic observations of DIBs
HD 183143 versus HD 204827
E(B-V)= 1.27 1.11
C2 C3
N(C2) < 6 1012 cm-2
= 440 1012 cm-2
High discrimination
N(CH) = 50 1012 cm-2
= 80 1012 cm-2
Poor discrimination
C2 richC2 poor
C2 rich
C2 poor
C2 DIBs
Minority
Weak and sharp
Diffuse Interstellar Bands
W(DIB) versus N(C2)
4984.82 År = 0.857
5418.92 År = 0.905
C2 DIBs Non-C2 DIBs
5780.59 År = 0.305
6397.39 År = 0.416
)]([
)(log
)6196(
)(log 2
VBEN
CN
W
XW
C2 DIBs
λ(Å) Δλ(Å) r(C2) r(C3) Note
4363.81 0.50 0.623 0.559
4734.77 0.39 0.797 0.795
4963.88 0.73 0.757 0.668
4969.14 0.79 0.856 0.640
4979.61 0.47 0.762 0.734
4984.79 0.50 0.857 0.593
5170.57 0.44 0.634 0.413
5176.04 0.69 0.843 0.687
5418.87 0.85 0.905 0.693
5512.68 0.57 0.684 0.431
5541.87 0.45 0.742 0.576
5546.48 0.53 0.802 0.787
5762.76 0.48
5769.16 0.49 0.749 0.565
5793.22 0.71
6729.25 0.44 0.782 0.782
21.3 cm-1
20.9 cm-1
20.4cm-1
15.0 cm-1
19.1 cm-1
Doublet Lines
The Doublets
4963.99
4969.24
4979.64
4984.82
5170.57
5176.04
5541.87
5546.48
5762.76
5769.16
21.3 cm-1
20.9 cm-1
20.4 cm-1
15.0 cm-1
19.1 cm-1
Π
Π
Π
Σ
HC3 HC5 HC6 HC7 HC8 C3- C7
- A (cm-1) 14.4 23.7 -15.1 26.2 -19.3 26.6 27.4
λ (Å) Δ
4.03.83.82.41.82.23.12.81.61.01.11.01.52.01.3
Tex
22 K
34 K
26 K
Π←Σ
3 106 s
Is / Iw
A
HD 204827HD 147889HD 172028
Or inverted
C2-rich HD 204827Hot HD 34078
T = 301 K
T = 40.6 K
C2 rich
C2 poor
C2 DIBs
Minority
Weak ans sharp
Keck Adamkovics, Blake and McCall
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992
517951785177517651755174
2( )
8B
T
B = 365 MHz for T = 100 K 182 MHz 200 K 122 MHx 300 K
B = 564.00 MHz HC7N 290.52 MHz HC9N 169.06 MHz HC11N
2.60 cm-1
Summary
DIBs which correlate well with C2 and C3 C2 DIB
HD 204827, Minority, Weak and sharp
Doublet structure suggests spin-orbit splitting Linear carbon chain molecule
Relatively high density ?
DIBs for high temperature medium HD 34078
Rotational structure B n 8 – 12?
Big question: C2, C3 C2 DIB or C2 DIB C2, C3?
HD 34078
T = 301 K
HD 204827
T = 40.6 K
C3
Adamkovics, Blake, McCall RA 06
The high temperature sightline HD 34078
R head