Identification of H(2)CCC as a diffuse interstellar band carrier

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DOIResolve DOI: http://doi.org/10.1088/0004-637X/726/1/41
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TypeArticle
Journal titleThe Astrophysical Journal
Volume726
Issue1
Article number41
Pages41-141-9; # of pages: 9
SubjectISM: general; ISM: lines and bands; ISM: molecules; methods: laboratory; techniques: spectroscopic
AbstractWe present strong evidence that the broad, diffuse interstellar bands (DIBs) at 4881 and 5450 angstrom are caused by the B(1)B(1) <- X(1)A(1) transition of H(2)CCC (l-C(3)H(2)). The large widths of the bands are due to the short lifetime of the B(1)B(1) electronic state. The bands are predicted from absorption measurements in a neon matrix and observed by cavity ring-down in the gas phase and show exact matches to the profiles and wavelengths of the two broad DIBs. The strength of the 5450 angstrom DIB leads to a l-C(3)H(2) column density of similar to 5 x 10(14) cm(-2) toward HD 183143 and similar to 2 x 10(14) cm(-2) to HD 206267. Despite similar values of E(B-V), the 4881 and 5450 angstrom DIBs in HD 204827 are less than one-third their strength in HD 183143, while the column density of interstellar C(3) is unusually high for HD 204827 but undetectable for HD 183143. This can be understood if C(3) has been depleted by hydrogenation to species such as l-C(3)H(2) toward HD 183143. There are also three rotationally resolved sets of triplets of l-C(3)H(2) in the 6150-6330 angstrom region. Simulations, based on the derived spectroscopic constants and convolved with the expected instrumental and interstellar line broadening, show credible coincidences with sharp, weak DIBs for the two observable sets of triplets. The region of the third set is too obscured by the alpha-band of telluric O(2).
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; NRC Herzberg Institute of Astrophysics
Peer reviewedYes
NPARC number19809243
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Record identifierfb6cce0e-4e68-417e-abef-a207e618ba28
Record created2012-04-13
Record modified2016-07-18
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