J/A+A/423/235 C5H2 Radiatively allowed transitions (Chandra+, 2004)
Suggestions for an interstellar C5H2 search
Chandra S., Shine S.A.
<Astron. Astrophys. 423, 235 (2004)>
=2004A&A...423..235C 2004A&A...423..235C
ADC_Keywords: Atomic physics ; Interstellar medium
Keywords: ISM: molecules
Abstract:
Laboratory detection of four isomers of C5H2 molecule have been
reported by Travers et al. (1997ApJ...483L.135T 1997ApJ...483L.135T), McCarthy et al.
(1997, Science, 275, 518), and Gottlieb et al. (1998ApJ...509L.141G 1998ApJ...509L.141G).
They suggested for detection of the ring-chain isomer of C5H2
(c-C5H2) in cosmic objects, as it is the most stable one in
comparison to the others. Two transitions 313-212 and 303-202
at 19.147GHz and 19.606GHz, respectively, of c-C5H2 have been
detected in TMC-1. We suggest that the c-C5H2 may be identified in
cool cosmic objects through its transition 313-404 at 4.3GHz
in absorption against the cosmic microwave background. Since in
absence of availability of the collisional rates, we have used scaled
values for them, we have checked the sensitivity of the lines on the
rates by enhancing the rate for the transitions with Δka=0 by
a factor of 10. Though the transitions are not found sensitive, our
results ma y be treated as qualitative in nature. This absorption line
may play an important role for identification of c-C5H2 in cosmic
objects.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 41 274 Radiatively allowed transitions
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See also:
J/A+A/402/1 : Einstein A-coefficients for C3H2 and C2CH4O (Chandra, 2003)
J/A+A/376/333 : Einstein A-coefficients for C3H4 (Sharma+, 2001)
J/A+AS/117/557 : Einstein A-coefficients for CO transitions (Chandra+ 1996)
J/A+AS/131/137 : Einstein A-Coefficients in SiC2 transitions (Chandra+ 1998)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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5- 13 A9 --- Ulevel Upper level
15- 17 A3 --- --- [⟹]
19- 27 A9 --- Llevel Lower Level
34- 41 E8.2 s-1 A Einstein A-coefficient for the transition
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Acknowledgements: Suresh Chandra
(End) Patricia Vannier [CDS] 07-Jul-2004