Detalles de publicación
PP 010037
A search for interstellar anthracene toward the Perseus anomalous microwave emission region
Instituto de Astrofisíca de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain;
Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain;
Consejo Superior de Investigaciones Científicas, Spain;
Dpto. de Astrofísica y Ciencias de la Atmósfera, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, E-28040
Madrid, Spain;
The W.J. McDonald Observatory, University of Texas, Austin, TX 78712-1083, USA
We report the discovery of a new broad interstellar (or circumstellar) band at 7088.8+/-2.0 A coincident to within the measurement uncertainties with the strongest band of the anthracene cation (C_{14}H_{10}^+) as measured in gas-phase laboratory spectroscopy at low temperatures (Sukhorukov et al.2004). The band is detected in the line of sight of star Cernis 52, a likely member of the very young star cluster IC 348, and is probably associated with cold absorbing material in a intervening molecular cloud of the Perseus star forming region where various experiments have recently detected anomalous microwave emission. From the measured intensity and available oscillator strength we find a column density of N_{an^+}= 1.1(+/-0.4) x 10^{13} cm^{-2} implying that ~ 0.008 % of the carbon
in the cloud could be in the form of C_{14}H_{10}^+. A similar abundance has been recently claimed for the naphthalene cation (Iglesias-Groth et al. 2008)
in this cloud. This is the first location outside the Solar System where specific PAHs are identified. We report observations of interstellar lines of CH
and CH^+ that support a rather high column density for these species and
for molecular hydrogen. The strength ratio of the two prominent diffuse
interstellar bands at 5780 and 5797 A suggests the presence of a ``zeta'' type cloud in the line of sight (consistent with steep far-UV extinction and high molecular content). The presence of PAH cations and other related hydrogenated carbon molecules which
are likely to occur in this type of clouds reinforce the suggestion that
electric dipole radiation from fast spinning PAHs is responsible of the anomalous microwave emission detected toward Perseus.
in the cloud could be in the form of C_{14}H_{10}^+. A similar abundance has been recently claimed for the naphthalene cation (Iglesias-Groth et al. 2008)
in this cloud. This is the first location outside the Solar System where specific PAHs are identified. We report observations of interstellar lines of CH
and CH^+ that support a rather high column density for these species and
for molecular hydrogen. The strength ratio of the two prominent diffuse
interstellar bands at 5780 and 5797 A suggests the presence of a ``zeta'' type cloud in the line of sight (consistent with steep far-UV extinction and high molecular content). The presence of PAH cations and other related hydrogenated carbon molecules which
are likely to occur in this type of clouds reinforce the suggestion that
electric dipole radiation from fast spinning PAHs is responsible of the anomalous microwave emission detected toward Perseus.