Hiroshi Shibai

Infrared polarimetry of the NGC 6334 V bipolar nebula

Exceptionally high degrees (up to about 100 percent) of polarization were observed in the L-prime band (3.8 microns) toward the NGC 6334 V bipolar nebula. The observed symmetric polarization pattern indicates that the nebula is a reflection nebula consisting of two lobes illuminated by a central obscured star. The distribution of polarization requires that one of the lobes consist of a lemon-shaped cavity which scatters light mainly at its surface, whereas a conical cavity model is appropriate for the other lobe. This asymmetry of the lobes is probably due to a density gradient in the ambient cloud material in this region. 17 refs.

Liquid-helium-cooled Fabry-Perot spectrometer and the frequency switching method for far-infrared spectroscopic observations

The Fabry-Perot spectrometer designed for NIR spectroscopic observations on the Balloon-borne Infrared Telescope (BIRT) is described in detail. Particular attention is given to the newly developed frequency switching method used in the BIRT, which is especially suitable for observations of spatially extended emission because the frequency switching mode does not require spacial chopping. Observations are described from two successful experiments conducted in 1988 using the Fabry-Perot spectrometer on the BIRT, in both the spatial chopping mode and the frequency switching mode.

Balloon-Borne Infrared Telescope for far-infrared spectroscopy

The Japanese-made Balloon-borne Infrared Telescope (BIRT) designed for FIR astronomy is described. The BIRT system includes a 50-cm-diam telescope; an attitude-control system consisting of an attitude stabilization and a pointing and tracking subsystems; the ground support system consisting of four personal-computer systems; and electronics consisting of three small computer systems, servo circuits, power amplifiers, and other small circuits. Between 1985 and 1988, the BIRT has flown eight times, demonstrating that it is able to provide a suitable telescope observations on a stable platform with a long integration time. Structural diagrams of the BIRT overall system, the optical system, and the wobbling mechanism are presented along with a block diagram of the on-board electronics.

A highly stable spectrophotometric capability for the Origins Space Telescope (OST) mid-infrared imager, spectrometer, coronagraph (MISC)

This paper describes the transit spectrograph designed for the Origins Space Telescope mid-infrared imager, spectrometer, coronagraph (MISC) and its performance derived through analytical formulation and numerical simulation. The transit spectrograph is designed based on a densified pupil spectroscopy design that forms multiple independent spectra on the detector plane and minimizes the systematic noise in the optical system. This design can also block any thermal light incoming into pixels around the transit spectra. The gain fluctuations occurring in the detector and readout electronics are accurately corrected by use of a number of blanked-off pixels. We found that the transit spectrograph for the OST concept 1 with a diameter of 9.3m potentially achieves the photon-noise-limited performance and allows detection of biosignature gases through transmission spectroscopy of transiting planets orbiting late- and middle-M type stars at 10 pc with 60 transit observations.

IS THE ANOMALOUS MICROWAVE EMISSION DUE TO THE ROTATION OF INTERSTELLAR PAHS? PLANCK RESULTS: PLANCK - AKARI PROJECT

We show how the rotation emission from isolated interstellar Polycyclic Aromatic Hydrocarbons (PAHs) can explain the so-called anomalous microwave emission (AME). AME has been discovered in the last decade as microwave interstellar emission (10 to 70 GHz) that is in excess compared to the classical emission processes: thermal dust, free-free and synchrotron. The PAHs are the interstellar planar nano-carbons responsible for the near infrared emission bands in the 3 to 15 micron range. Theoretical studies show that under the physical conditions of the interstellar medium (radiation and density) the PAHs adopt supra-thermal rotation velocities, and consequently they are responsible for emission in the microwave range. The first results from the PLANCK 1 mission unexpectedly showed that the AME is not only emitted by specific galactic interstellar clouds, but it is present throughout the galactic plane, and is particularly strong in the cold molecular gas. The comparison of theory and observations shows that the measured emission is fully consistent with rotation emission from interstellar PAHs. We draw the main lines of our PLANCK-AKARI collaborative program which intends to progress on this question by direct comparison of the near infrared (AKARI) and microwave (PLANCK) emissions of the galactic plane.

SPICA coronagraph instrument: characterization of atmospheres and physical parameters of giant planets by direct imaging and spectroscopy

We present the current status of the development of the SPICA Coronagraph Instrument (SCI). SPICA is a next-generation 3-meter class infrared telescope, which will be launched in 2022. SCI is high-contrast imaging, spectroscopic instrument mainly for direct detection and spectroscopy of extra-solar planets in the near-to-mid infrared wavelengths to characterize their atmospheres, physical parameters and evolutionary scenarios. SCI is now under the international review process. In this paper, we present a science case of SCI. The main targets of SCI, not only for direct imaging but also for spectroscopy, are young to matured giant planets. We will also show that some of known exoplanets by ground-based direct detection are good targets for SCI, and a number of direct detection planets that are suitable for SCI will be significantly increased in the next decade. Second, a general design of SCI and a key technology including a new high-throughput binary mask coronagraph, will be presented. Furthermore, we will show that SCI is potentially capable of achieving 10-6 contrast by a PSF subtraction method, even with a telescope pointing error. This contrast enhancement will be important to characterize low-mass and cool planets.

Astronomical Far-Infrared FTS of the FIS Instrument onboard the ASTRO-F satellite

The far-infrared Fourier transform spectrometer is developed for an application of the astronomical satellite ASTRO-F. FIS-FTS is the unique instrument which covers 50 - 200 μm wavelength range with spectral resolution of 0.3cm-1.