K. Kawaguchi

Observations of some oxygen-containing and sulfur-containing organic molecules in cold dark clouds.

Observations of nine oxygen- and sulfur-containing organic molecules have been made toward the cold dark clouds TMC-1 and L134N. We have confirmed the presence of para-ketene (H2C2O) in TMC-1, have for the first time observed ortho-ketene, and find a total ketene column density approximately 1 x 10(13) cm-2. Thioformaldehyde (H2CS) is easily detectable in both TMC-1 and L134N, with a column density about 5 times larger in the former source (approximately 3 x 10(13) cm-2). The fractional abundance of ketene is comparable to the predictions of ion-molecule chemistry, while that of thioformaldehyde in TMC-1 is one to two orders of magnitude greater than that expected from such models at steady state. Interstellar sulfur chemistry thus continues to be poorly understood. We set upper limits for the column densities of formic acid (HCOOH), vinyl alcohol (CH2CHOH), methyl formate (HCO2CH3), formamide (NH2CHO), methyl mercaptan (CH3SH), isothiocyanic acid (HNCS), and thioketene (H2C2S) in both sources.

SUBMILLIMETER-WAVE ROTATIONAL SPECTROSCOPY OF H2F+

Author Institution: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1; Tsushima-Naka, Okayama 700-8530, Japan; Department of Chemistry and Department of Physics and Astronomy; University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada

Detection of extragalactic CF+ toward PKS 1830−211 - Chemical differentiation in the absorbing gas

We report the first extragalactic detection of CF+, the fluoromethylidynium ion, in the z=0.89 absorber toward PKS1830-211. We estimate an abundance of ~3E-10 relative to H2 and that ~1% of fluorine is captured in CF+. The absorption line profile of CF+ is found to be markedly different from that of other species observed within the same tuning, and is notably anti-correlated with CH3OH. On the other hand, the CF+ profile resembles that of [C I]. Our results are consistent with expected fluorine chemistry and point to chemical differentiation in the column of absorbing gas.

Detection of ammonia in M 51

Aims. To study the abundance and temperature of ammonia in the center of a nearby galaxy M 51 and to compare them with those in other nearby galaxies, we observed its (J,K) = (1, 1), (2, 2), (3, 3), and (4, 4) inversion transitions at the wavelength of 1.3 cm. Methods. The observations were carried out with the Effelsberg 100-m radio telescope. Results. The (1, 1), (2, 2), and (3, 3) transitions are clearly detected, but the (4, 4) transition is barely detected. The rotational temperature obtained from the (1, 1) and (2, 2) transitions of para-ammonia is 25 ± 2 K, which is similar to those of M 82 and the Large Magellanic Cloud (N 159 W), but significantly lower than those of IC 342 and NGC 1068 among the nearby galaxies. The column density of ammonia is (8.1 ± 2.4) × 10 13 cm −2 , and the abundance relative to H2 is ∼4.5 × 10 −9 . The abundance in M 51 is about a factor of 5 lower than those of NGC 253 and IC 342, but about one order of magnitude higher than those of M 82 and the Large Magellanic Cloud. The addition of the data of M 51 further supports the exceptionally low abundances of ammonia reported previously in these two galaxies. For understanding the abundance of ammonia in M 51 and other nearby galaxies, their temperatures were compared. As a result, we found that the galaxies with low temperature tend to have low abundance of ammonia. In addition, the photodissociation rate of ammonia was compared to those of related molecules detected in the nearby galaxies to discuss the effect of photodissociation. We found that the low abundance of ammonia in some galaxies cannot be explained only by the effect of photodissociation.

Development of a mid-infrared high dispersion spectrograph (IRHS) for the Subaru telescope

A design of prototype Infra-Red High-dispersion Spectrograph (IRHS) is described. IRHS is a cryogenic echelle spectrometer for 8.2-m Subaru Telescope, which will operate at 8 to 13 μm with resolving power of 200,000. To achieve such a high dispersion and broad bandwidth, a Germanium immersion echelle grating was adopted. As a preliminary step, we started to develop the proto-type of IRHS (ProtoIRHS) with currently available Ge immersion grating (30x30x72 mm) and one 512x412 Si:As impurity band detector array, which will provide the maximum resolving power of 50,000 at 10 μm with slit width of 0.612 arcseconds (0.48 mm) and two-pixels sampling.

First light observation of GIGMICS (germanium immersion grating mid-infrared cryogenic spectrograph) by Kanata 1.5-m Telescope at Higashi-Hiroshima Observatory

We have developed a germanium immersion grating mid-infrared cryogenic spectrograph (GIGMICS) designed for the Nasmyth focus stage of NAOJ Subaru 8.2-m telescope, which operates at N-band (8-13 μm) in wavelength (λ) with maximum resolving power R（≡λ/Δλ） ~ 50,000. A single crystal germanium echelle immersion grating (30 × 30 × 72 mm) for collimated beam size of 28 mmφ was fabricated by utilizing ultra precision micro-grinding method coupled with the ELID (ELectrolytic In-process Dressing) technique (Ohmori, H. 1992, Ebizuka et al. 2003, Tokoro et al. 2003). After the critical test for the application to the laboratory gas-phase IR high-resolution spectroscopy(Hirahara et al. 2010), we have conducted the “first light” astronomical observation of GIGMICS by the Kanata 1.5-m telescope at Higashi- Hiroshima Observatory from January to April, 2011. Toward many astronomical objects such as the Moon, Venus, Jupiter, circumstellar envelopes of late-type stars, proto-planetary nebulae, and interstellar molecular clouds in the vicinity of star-forming regions, we conducted spectroscopic observations in the N-band region.

Systematically Peculiar Molecular Composition in M 82: Regarding the Formation Mechanisms

A systematically peculiar molecular composition has been found in a nearby starburst galaxy M 82. Molecules related to grain surface formation and to production reactions favorable at high-temperature are deficient in M 82 among nearby galaxies with rich gas. These molecules are SO, SiO, NH 3 , HNCO, CH 3 OH, and CH 3 CN. Possible reasons for this peculiarity are discussed.