Setsuko Wada

A PLANETARY COMPANION TO THE G-TYPE GIANT STAR HD 104985

We report the detection of a planetary-mass companion to the G9 III giant star HD 104985 from precise Doppler velocity measurements made using the High Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory. The radial velocity variability of this star is best explained by an orbital motion with a period of 198.2 ± 0.3 days, a velocity semiamplitude of 161 ± 2 m s-1, and an eccentricity of 0.03 ± 0.02. Assuming a stellar mass of 1.6 M☉, we obtained a minimum mass and a semimajor axis of 6.3MJ and 0.78 AU, respectively, for the companion. A probable upper limit to the stellar mass of 3 M☉ yielded m2 sin i = 9.6MJ, which falls in the planetary-mass regime. This is the first discovery of a planetary companion orbiting a G-type giant star.

Infrared spectrum of quenched carbonaceous composite (QCC). II. A new identification of the 7. 7 and 8. 6 micron unidentified infrared emission bands

Infrared spectrum of oxidized quenched carbonaceous composite (QCC) is presented. In addition to the features seen in unoxidized QCC, new features appear at 7.7 and 8.6 microns and the strengths of the features at 6.2, 7.3, and 11.4 microns increase. The infrared features of oxidized QCC are in good agreement with nine of 11 members of the unidentified infrared (UIR) emission bands. The absorption bands of QCC are all broad without fine structure, clearly different from sharp bands of molecules. The 7.7 and 8.6 micron features can be attributed to a cross-conjugated ketone molecular structure. A possible identification of the UIR 7.7 and 8.6 micron bands with this structure is discussed. The present results indicate that oxygen can play an important role in the structures of the UIR emitting material as well as carbon and hydrogen. 29 references.

Quenched carbonaceous composite : fluorescence spectrum compared to the extended red emission observed in reflection nebulae

The photoluminescence (fluorescence) of a film of the laboratory-synthesized quenched carbonaceous composite (filmy QCC) is shown to have a single broad emission feature with a peak wavelength that varies from 670 to 725 nm, and coincides with that of the extended red emission observed in reflection nebulae. The rapid decay of the filmy QCC red fluorescence in air and of the stable blue fluorescence of the filmy QCC dissolved in liquid Freon suggests that the red fluorescence originates from the interaction of active chemical species and aromatic components in the filmy QCC. A material similar in nature to that of the filmy QCC may be a major component of interstellar dust.

Comparison of the absorption curves of soots, pitch samples and QCCs to the interstellar extinction curve

Abstract QCC (Quenched Carbonaceous Composite) is an amorphous carbonaceous material formed from a hydrocarbon plasma. In a previous paper (Sakata et al., Astrophys. J.430, 311–316, 1994), we have studied two forms of QCC: a dark QCC component located near the plasmic beam and a thermally-altered filmy QCC. Both types of QCC derivatives show an absorption feature near 217 nm, but with different extinction magnitude. A mixture of dark QCC and thermally-altered filmy QCC can explain the variations in the interstellar peak extinction. In this paper we show that soot produced from methane. methane-hydrogen gas mixtures and specially produced pitches have a broad extinction feature centered at about 217 nm. The extinction magnitude of the soots and the pitches is lower than that of the average interstellar extinction curve. We discuss the cause of the 217 nm extinction feature of soot, pitches and QCCs, and we suggest that short peripheral carbon chain structures containing π electron conjugation give rise to the 217 nm extinction feature.

Chemical, optical, and infrared properties of quenched carbonaceous composites (QCCS)

Quenched carbonaceous composite (QCC) was synthesized by quenching the plasma of methane gas. Chemical properties as well as optical and infrared spectra of the QCC and “oxidized” QCC were measured. Good agreement of the IR spectra of the QCCs to the unidentified infrared (UIR) emission bands was obtained. Correspondence of their features to molecular structures in the QCC was estimated. It is concluded that a “cross-conjugated ketone” structure (CCK) caused the 6.2, 7.7, and 8.6 μm features and “solo” H atoms on carbon are responsible for the 3.3 and 11.3 μm features.

Carbonaceous Onion-Like Particles: A Possible Component of the Interstellar Medium

A carbonaceous material formed from a hydrocarbon plasma called quenched carbonaceous composite (QCC) is shown to have functional groups that approximate the positions of the interstellar 217.5 nm absorption and the infrared emission features at 3.3—11.3 μm. A form of this material, called “dark-QCC” has abundant carbonaceous onion-like particles. We present the results of various experiments involving QCC and conjecture that the carbonaceous onion-like particles in QCC may be a good laboratory analog to the carrier of the interstellar absorption and emission features. A scenario for dust formation from carbonaceous onion-like particles is presented.

Simulation of the Formation of Dust Grains in Space by a Plasma Jet Apparatus

Using a vacuum-tight plasma jet apparatus operated below one atmosphere, the condensation of solid particles in space was experimentally simulated. Atomized reactant gases consisting of Si, O, C, and H atoms generated in the plasma flame were injected into a reactor chamber filled with Ar gas of 200 Torr, and quenched into solid particles. The formed grains had irregular shapes and their sizes were smaller than 20 nm. X-ray diffraction patterns of the condensed grains showed no sharp peaks. It was found from IR absorption spectra that the particles contained C-H, Si-O, and Si-C bonds, irrespective of their initial abundances. These characteristics of the condensates were clearly different from those expected from equilibrium calculations.

Grain Formation Experiments by a Plasma Jet Apparatus

The observational fact that the interstellar and circumstellar dust grains are not crystalline but amorphous has been accumulated and it leads to the idea that the grain formation in space is a non-equilibrium phenomenon. In order to investigate the non-equilibrium condensation, we have developed a plasma jet apparatus. The high power of the apparatus enables to dissociate molecular sample gas completely and to obtain condensates from atomized gas. The purpose of our experiments is to examine the condensates from rapidly cooled atomized gas with various abundance ratios. In the experiments, we first focused on the condensation from mixtures of H, C, O, and Si atoms. Three kinds of gas mixtures, a mixture af H and C atoms, that of H, C, and Si atoms, and that of H, C, O, and Si atoms, were chosen as reactant condensable gases. Our experiments were executed with entirely new features: (1) condensation from atomized gas and (2) condensation from mixtures of silicon, oxygen, carbon and hydrogen atoms.

In situ observation of structural alteration process of filmy quenched carbonaceous composite

The thermal alteration process of filmy quenched carbonaceous composite (filmy QCC) has been studied in situ by high-resolution transmission electron microscopy (HRTEM). HRTEM images of the as-prepared filmy QCC showed the typical amorphous carbon film structure. By heating above 300 ◦C, the structural alteration takes place. Curled graphene structure started to appear at 300 ◦C. Distorted onion-like structure similar to dark QCC appeared above 500 to 700 ◦C. The distorted onion-like structure that appears at 700 ◦C after heating for 30 minutes also appeared by heating at 450 ◦C for 2 hours.