Details
| Original language | English |
|---|---|
| Pages (from-to) | 1053-1060 |
| Number of pages | 8 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 397 |
| Issue number | 2 |
| Early online date | 17 Jul 2009 |
| Publication status | Published - Aug 2009 |
Abstract
Polycyclic Aromatic Hydrocarbons (PAHs) are widely accepted as the carriers of the Aromatic Infrared Bands (AIBs), but an unambiguous identification of any specific interstellar PAH is still missing. For polar PAHs, pure rotational transitions can be used as spectral fingerprints for identification. Combining dedicated experiments, detailed simulations and observations, we explore d the mm wavelength domain to search for specific rotational transitions of corannulene (C 20H 10). We performed high-resolution spectroscopic measurements and a simulation of the emission spectrum of ultraviolet-excited C 20H 10 in the environment of the Red Rectangle (RR), calculating its synthetic rotational spectrum. Based on these results, we conducted a first observational campaign at the IRAM 30-m telescope towards this source to search for several high-J rotational transitions of C 20H 10. The laboratory detection of the J = 112 ← 111 transition of corannulene showed that no centrifugal splitting is present up to this line. Observations with the IRAM 30-m telescope towards the RR do not show any corannulene emission at any of the observed frequencies, down to a rms noise level of T mb = 8 mK for the J =135 → 134 transition at 137.615 GHz. Comparing the noise level with the synthetic spectrum, we are able to estimate an upper limit to the fraction of carbon locked in corannulene of about 1.0 × 10 -5 relative to the total abundance of carbon in PAHs. The sensitivity achieved in this work shows that radio spectroscopy can be a powerful tool to search for polar PAHs. We compare this upper limit with models for the PAH size distribution, emphasizing that small PAHs are much less abundant than predicted. We show that this cannot be explained by destruction but is more likely related to the chemistry of their formation in the environment of the RR.
Keywords
- Astrochemistry, ISM: abundances, ISM: individual: Red Rectangle, ISM: lines and bands, ISM: molecules
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Astronomy and Astrophysics
- Earth and Planetary Sciences(all)
- Space and Planetary Science
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In: Monthly Notices of the Royal Astronomical Society, Vol. 397, No. 2, 08.2009, p. 1053-1060.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Search for corannulene (C 20H 10) in the Red Rectangle
AU - Pilleri, P.
AU - Herberth, D.
AU - Giesen, T. F.
AU - Gerin, M.
AU - Joblin, C.
AU - Mulas, G.
AU - Malloci, G.
AU - Grabow, J. U.
AU - Brünken, S.
AU - Surin, L.
AU - Steinberg, B. D.
AU - Curtis, K. R.
AU - Scott, L. T.
PY - 2009/8
Y1 - 2009/8
N2 - Polycyclic Aromatic Hydrocarbons (PAHs) are widely accepted as the carriers of the Aromatic Infrared Bands (AIBs), but an unambiguous identification of any specific interstellar PAH is still missing. For polar PAHs, pure rotational transitions can be used as spectral fingerprints for identification. Combining dedicated experiments, detailed simulations and observations, we explore d the mm wavelength domain to search for specific rotational transitions of corannulene (C 20H 10). We performed high-resolution spectroscopic measurements and a simulation of the emission spectrum of ultraviolet-excited C 20H 10 in the environment of the Red Rectangle (RR), calculating its synthetic rotational spectrum. Based on these results, we conducted a first observational campaign at the IRAM 30-m telescope towards this source to search for several high-J rotational transitions of C 20H 10. The laboratory detection of the J = 112 ← 111 transition of corannulene showed that no centrifugal splitting is present up to this line. Observations with the IRAM 30-m telescope towards the RR do not show any corannulene emission at any of the observed frequencies, down to a rms noise level of T mb = 8 mK for the J =135 → 134 transition at 137.615 GHz. Comparing the noise level with the synthetic spectrum, we are able to estimate an upper limit to the fraction of carbon locked in corannulene of about 1.0 × 10 -5 relative to the total abundance of carbon in PAHs. The sensitivity achieved in this work shows that radio spectroscopy can be a powerful tool to search for polar PAHs. We compare this upper limit with models for the PAH size distribution, emphasizing that small PAHs are much less abundant than predicted. We show that this cannot be explained by destruction but is more likely related to the chemistry of their formation in the environment of the RR.
AB - Polycyclic Aromatic Hydrocarbons (PAHs) are widely accepted as the carriers of the Aromatic Infrared Bands (AIBs), but an unambiguous identification of any specific interstellar PAH is still missing. For polar PAHs, pure rotational transitions can be used as spectral fingerprints for identification. Combining dedicated experiments, detailed simulations and observations, we explore d the mm wavelength domain to search for specific rotational transitions of corannulene (C 20H 10). We performed high-resolution spectroscopic measurements and a simulation of the emission spectrum of ultraviolet-excited C 20H 10 in the environment of the Red Rectangle (RR), calculating its synthetic rotational spectrum. Based on these results, we conducted a first observational campaign at the IRAM 30-m telescope towards this source to search for several high-J rotational transitions of C 20H 10. The laboratory detection of the J = 112 ← 111 transition of corannulene showed that no centrifugal splitting is present up to this line. Observations with the IRAM 30-m telescope towards the RR do not show any corannulene emission at any of the observed frequencies, down to a rms noise level of T mb = 8 mK for the J =135 → 134 transition at 137.615 GHz. Comparing the noise level with the synthetic spectrum, we are able to estimate an upper limit to the fraction of carbon locked in corannulene of about 1.0 × 10 -5 relative to the total abundance of carbon in PAHs. The sensitivity achieved in this work shows that radio spectroscopy can be a powerful tool to search for polar PAHs. We compare this upper limit with models for the PAH size distribution, emphasizing that small PAHs are much less abundant than predicted. We show that this cannot be explained by destruction but is more likely related to the chemistry of their formation in the environment of the RR.
KW - Astrochemistry
KW - ISM: abundances
KW - ISM: individual: Red Rectangle
KW - ISM: lines and bands
KW - ISM: molecules
UR - http://www.scopus.com/inward/record.url?scp=67651102673&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2966.2009.15067.x
DO - 10.1111/j.1365-2966.2009.15067.x
M3 - Article
AN - SCOPUS:67651102673
VL - 397
SP - 1053
EP - 1060
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 2
ER -