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AKARI, formerly known as ASTRO-F, is the second Japanese space mission to perform infrared astronomical observations. AKARI was launched on 21 February 2006 (UT) and brought into a sun-synchronous polar orbit at an altitude of 700 km by a JAXA M-V rocket. AKARI has a telescope with a primary-mirror aperture size of 685 mm together with two focal-plane instruments on board: the Infrared Camera (IRC), which covers the spectral range 2–26 μm and the Far-Infrared Surveyor (FIS), which operates in the range 50–180 μm. The telescope mirrors are made of sandwich-type silicon carbide, specially developed for AKARI. The focal-plane instruments and the telescope are cooled by a unique cryogenic system that kept the telescope at 6K for 550 days with 180 l super-fluid liquid Helium (LHe) with the help of mechanical coolers on board. Despite the small telescope size, the cold environment and the state-of-the-art detectors enable very sensitive observations at infrared wavelengths. To take advantage of the characteristics of the sun-synchronous polar orbit, AKARI performed an all-sky survey during the LHe holding period in four far-infrared bands with FIS and two mid-infrared bands with IRC, which surpasses the IRAS survey made in 1983 in sensitivity, spatial resolution, and spectral coverage. AKARI also made over 5,000 pointing observations at given targets in the sky for approximately 10 min each, for deep imaging and spectroscopy from 2 to 180 μm during the LHe holding period. The LHe ran out on 26 August 2007, since which date the telescope and instrument are still kept around 40K by the mechanical cooler on board, and near-infrared imaging and spectroscopic observations with IRC are now being continued in pointing mode.

The near-infrared spectrum of Titan, Saturn's largest moon and one of the Cassini/Huygens' space mission primary targets, covers the 0.8 to 5 micron region in which it shows several weak CH 4 absorption regions, and in particular one centered near 2.75 micron. Due to the interference of telluric absorption, only part of this window region (2.9–3.1 μm) has previously been observed from the ground [Noll, K.S., Geballe, T.R., Knacke, R., Pendleton, F., Yvonne, J., 1996. Icarus 124, 625–631; Griffith, C.A., Owen, T., Miller, G.A., Geballe, T., 1998. Nature 395, 575–578; Griffith, C.A., Owen, T., Geballe, T.R., Rayner, J., Rannou, P., 2003. Science 300, 628–630; Geballe, T.R., Kim, S.J., Noll, K.S., Griffith, C.A., 2003. Astrophys. J. 583, L39–L42]. We report here on the first spectroscopic observations of Titan covering the whole 2.4–4.9 μm region by two instruments on board the Infrared Space Observatory (ISO) in 1997. These observations show the 2.75-μm window in its complete extent for the first time. In this study we have also used a high-resolution Titan spectrum in the 2.9–3.6 μm region taken with the Keck [Geballe, T.R., Kim, S.J., Noll, K.S., Griffith, C.A., 2003. Astrophys. J. 583, L39–L42; Kim, S.J., Geballe, T.R., Noll, K.S., Courtin, R., 2005. Icarus 173, 522–532] to infer information on the atmospheric parameters (haze extinction, single scattering albedo, methane abundance, etc.) by fitting the methane bands with a detailed microphysical model of Titan's atmosphere (updated from Rannou, P., McKay, C.P., Lorenz, R.D., 2003. Planet. Space Sci. 51, 963–976). We have included in this study an updated version of a database for the CH 4 absorption coefficients [STDS, Wenger, Ch., Champion, J.-P., 1998. J. Quant. Spectrosc. Radiat. Transfer 59, 471–480. See also http://www.u-bourgogne.fr/LPUB/TSM/sTDS.html for latest updates; Boudon, V., Champion, J.-P., Gabard, T., Loete, M., Michelot, F., Pierre, G., Rotger, M., Wenger, Ch., Rey, M., 2004. J. Mol. Spectrosc. 228, 620–634]. For the atmosphere we find that (a) the haze extinction profile that best matches the data is one with higher (by 40%) extinction in the atmosphere with respect to Rannou et al. (2003) down to about 30 km where a complete cut-off occurs; (b) the methane mixing ratio at Titan's surface cannot exceed 3% on a disk-average basis, yielding a maximum CH 4 column abundance of 2.27 km-am in Titan's atmosphere. From the derived surface albedo spectrum in the 2.7–3.08 micron region, we bring some constraints on Titan's surface composition. The albedo in the center of the methane window varies from 0.01 to 0.08. These values, compared to others reported in the other methane windows, show a strong compatibility with the water ice spectrum in the near-infrared. Without confirming its existence from this work alone, our data then appear to be compatible with water ice. A variety of other ices, such as CO 2 , NH 3 , tholin material or hydrocarbon liquid cannot be excluded from our data, but an additional unidentified component with a signature around 2.74 micron is required to satisfy the data.

We present spectroscopic observations of the classical nova CP Crucis (Nova Crux 1996) obtained with the Infrared Space Observatory Short Wavelength Spectrometer (ISO SWS) and the Anglo-Australian Telescope using both the Infrared Imaging Spectrograph and the Royal Greenwich Observatory Spectrograph. From the expansion parallax, we find that CP Crucis lies at a distance of 2.6 ± 0.5 kpc and reached a maximum MV of -8.7 at 0.96 days after discovery. We find abundance enhancements versus solar by mass of 75, 17, and 27 for N, O, and Ne, respectively. Additionally, we constrain the Mg abundance in the ejecta to be approximately solar. Abundance analysis suggests CP Crucis is an old Population I binary system. Combining the strong N and Ne abundances with the relatively low Mg abundance and a Ne/O ratio of 0.5, we propose that CP Crucis is an example of the "missing link" between CO and ONeMg novae.

We have analyzed Titan observations performed by the Infrared Space Observatory (ISO) in the range 7–30 μm. The spectra obtained by three of the instruments on board the mission (the short wavelength spectrometer, the photometer, and the camera) were combined to provide new and more precise thermal and compositional knowledge of Titan’s stratosphere. With the high spectral resolution achieved by the SWS (much higher than that of the Voyager 1 IRIS spectrometer), we were able to detect and separate the contributions of most of the atmospheric gases present on Titan and to determine disk-averaged mole fractions. We have also tested existing vertical distributions for C2H2, HCN, C2H6, and CO2 and inferred some information on the abundance of the first species as a function of altitude. From the CH3D band at 1161 cm−1 and for a CH4 mole fraction assumed to be 1.9% in Titan’s stratosphere, we have obtained the monodeuterated methane-averaged abundance and retrieved a D/H isotopic ratio of 8.7−1.9+3.2 × 10−5. We discuss the implications of this value with respect to current evolutionary scenarios for Titan. The ν5 band of HC3N at 663 cm−1 was observed for the first time in a disk-averaged spectrum. We have also obtained a first tentative detection of benzene at 674 cm−1, where the fit of the ISO/SWS spectrum at R = 1980 is significantly improved when a constant mean mole fraction of 4 × 10−10 of C6H6 is incorporated into the atmospheric model. This corresponds to a column density of ∼ 2 × 1015 molecules cm−2 above the 30-mbar level. We have also tested available vertical profiles for HC3N and C6H6 and adjusted them to fit the data. Finally, we have inferred upper limits of a few 10−10 for a number of molecules proposed as likely candidates on Titan (such as allene, acetonitrile, propionitrile, and other more complex gases).

Several observational programmes were conducted with ISO (Kessler et al., 1996) aiming at the investigation of the near- and far- infrared spectrum of the satellites of the giant planets. Thus, Jupiter's satellites Callisto, Io and Ganymede were explored mainly with the spectrometers, while the spectrum of Titan, Saturn's largest satellite, was investigated thoroughly by all the instruments. The analysis of the data has provided original and precious information on the satellites' surfaces and Titan's atmosphere in particular.

We present observations of the classical nova V1425 Aquilae (Nova Aquila 1995) with the Infrared Space Observatory's (ISO) Short Wavelength Spectrometer, the Isaac Newton Telescope's Intermediate Dispersion Spectrograph, and the International Ultraviolet Explorer's Short-Wavelength Primary Spectrograph. Analysis of He II (1640 A) development constrains the white dwarf turnoff to ~400 days after outburst. Photoionization modeling of the optical and ISO spectra obtained during the late nebular phase constrains the mass of the ejecta between 2.5–4.2 × 10-5 M⊙. This modeling also suggests C and O in the ejecta were enhanced by a factor of ~9, and N was enhanced by a factor of ~100 with respect to solar, while Ne was only slightly enhanced. Based upon these analyses, we determine that the white dwarf in the V1425 Aql system has a CO composition and is at a distance of 3.0 ± 0.4 kpc.

We present ISO SWS and LWS observations of the symbiotic star HM Sge. The infrared emission longward of ~5μ m is dominated by a silicate dust shell. There is a number of high ionization emission lines superimposed on the dust continuum. The ISO continuum spectra can be fitted with a single, optically thick silicate dust shell but such a model does not fit other known properties of this system, such as the observed colours, the optical visibility of the red giant and the occurrence of a dust obscuration event. We favour a two component model in which in addition to a partial Mira dust shell, a second dust component is associated with the hot source. This second shell is located at the interface between the Mira dust shell and the dust free region carved out by the hot component. This picture corresponds closely to that deduced independently from radio observations. The two dust components are very different. The dust envelope associated with the Mira is very extended and optically thin, whereas the second dust component is geometrically rather thin but dust rich. The model not only fits the ISO data reasonably well, but is also compatible with other IR properties of HM Sge. The thin dust shell contributes strongly to the dust emission over most of the ISO range. It may be the combination of the two shells that makes a symbiotic a D type. The general agreement of the present models with ISO observations indicate that radiation (rather than collisions) as the main dust heating mechanism is sufficient.

We present a trend analysis of the ISO-SWS detector performance and a study of the space radiation effects on the SWS detectors. In particular, dark currents, dark current noise and detector responses have been checked as a function of time through the mission and as a function of time in arevolution. The results show that these parameters were stable during the mission in all bandsbut for band 3 (Si:As). Dark currents and responses were found to be higherin the first hours following the start of the science window,especially in band 2 (Si:Ga). We have studied the impacts of cosmic rays and radiation belt particles on the SWS detectors, as well as of the only large solar proton event on November 6, 1997,that occurred during the ISO mission (operated during solar minimum).The observed glitch rates in all SWS bands are found to be between 2 and4 times higher than the value predicted by the CREME96 model for the cosmic ray flux in the period considered. The bands that registered the highest glitch rates showed also a correlation with the electron fluxes measured on theGOES 9 spacecraft. From the distribution of glitchheights (voltage jumps in the detector signal), we have derived the deposited energy distributions of the particles hits. Our results lead to the conclusion that secondaryparticles produced in the shield and the detectors contributed at least as much as cosmic rays to the observed glitch rate. The effects on the detectors of the November 6, 1997 event, which caused that all observationsin a revolution were declared failed, are described in detail.

The: [O IV] lambda 25.89 fine-structure line has been detected in Nova Cassiopeiae 1993 (V705 Cas) by the Short Wavelength Spectrometer on the Infrared Space Observatory (ISO). Preliminary analysis using CLOUDY suggests that oxygen is overabundant relative to solar by at least 25 (by number), and that the abundance of neon is 0.5 x solar at most; the hydrogen density at the time of the ISO observation is in the range 10(4.1) less than or similar to n(H)(cm(-3)) less than or similar to 10(4.65). The dust shell, which was prominent in the near infrared in earlier ground-based observations, was not detected by:the ISO.

We present low resolution spectrophotometric and imaging ISO observations of a sample of 58 AGN's over the 2.5–11.6 μ range. The data strongly support unification schemes and set new constraints on models of the molecular torus.

We present near (ground-based) and far (ISO) infrared spectroscopy of Sakurai's object. As in the case of the optical spectrum, between 1996 and 1997 April the near-infrared spectrum underwent a dramatic change to later spectral type, and there is some evidence that the spectrum continued to evolve during 1997. Molecular features of carbon-bearing molecules (CN, C2, CO) — corresponding to those seen in cool carbon stars — are now prominent in the 1–2.5 μ m range, and the 12C/13C ratio is low. The ISO data demonstrate the presence of hot circumstellar dust at a temperature of ∼ 680 K. If the dust shell is optically thin, the dust mass is ∼ 2.8 × 10−8 M⊙.

We report accurate new wavelengths for 29 mid-infrared ionic fine-structure lines, based on observations with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). Our results originate from observations of NGC 7027, NGC 6543, NGC 6302, the Circinus galaxy, Sgr A West, and W51 IRS 2. The obtained accuracies (λ/Δλ) range from 3 × 104 to 1 × 105, depending on instrumental mode and uncertainty in radial velocities.

Bright source catalogues based on the new mid- and far-infrared all-sky survey by the infrared astronomical satellite AKARI were released into the public domain in March 2010. The mid-infrared catalogue contains more than 870 thousand sources observed at 9 and 18 μm, and the far-infrared catalogue provides information of about 427 thousand sources at 65, 90, 140, and 160 μm. The AKARI catalogues will take over the IRAS catalogues and will become one of the most important catalogues in astronomy. We present the characteristics of the AKARI infrared source catalogues as well as current activity for the future versions.

著者人数：33名, Accepted: 2010-02-17, 資料番号: SA1001050000

Almost 5 billion years ago, the Sun formed in a local contraction of a cloud of molecular gas. A rotating disk of gas and dust is believed to have fed material onto the proto-Sun for the first few million years of its life, and to have formed the planets, comets and other Solar System objects. Similar disks, but with less mass, have been observed around a few main-sequence stars such as Vega1. The dust particles orbiting stars like Vega will be removed on timescales of the order of 1 Myr (Vega is about 350 Myr old), and therefore must be resupplied1, at least for a time. But earlier surveys2,3 lacked the sensitivity to determine how many nearby stars have dust disks, and to investigate how long such disks survive. Here we report infrared observations indicating that most stars younger than 300 Myr have dust disks, while most older than 400 Myr do not: ninety per cent of the disks disappear when the star is between 300 and 400 Myr old. Several events that are related to the ‘clean up’ of debris in the early history of our Solar System have a similar timescale.

AKARI is the first Japanese astronomical infrared satellite mission orbiting around the Earth in a sun-synchronous polar orbit at the altitude of 700 km. One of the major observation programs of the AKARI is an all-sky survey in the mid- to far-infrared spectral regions with 6 photometric bands. The mid-infrared part of the AKARI All-Sky Survey was carried out with the Infrared Camera (IRC) at the 9 and 18 µm bands with the sensitivity of about 50 and 120 mJy (5σ per scan), respectively. The spatial resolution is about 9.4" at both bands. AKARI mid-infrared (MIR) all-sky survey substantially improves the MIR dataset of the IRAS survey of two decades ago and provides a significant database for studies of various fields of astronomy ranging from star-formation and debris disk systems to cosmology. This paper describes the current status of the data reduction and the characteristics of the AKARI MIR all-sky survey data.

ESA Science Archives for ISO and XMM-Newton have been developed by the Science Operations and Data Systems Division in Villafranca, Spain. By using an open 3-tier architecture (Data Products and Database, Business Logic, User Interface) together with Java and XML technology, inter-operability has been achieved from these archives to external archives (NED/ SIMBAD, ADS, IRAS). Furthermore, that has allowed external archives (CDS, ADS, IRSA, HEASARC) to directly access ISO and XMM-Newton data without going through their standard user interfaces.

As part of the Astrophysical Virtual Observatory (AVO) we are developing an interoperability prototype which aims to federate a set of astronomical archives, representative of a variety of techniques (space/ground, images/spectra, X-ray to radio wavelengths) into the CDS VizieR and Aladin tools. The target archives for federation are: VLT, NTT, EIS (ESO), HST/ECF, ISO, XMM (ESA), Wide field UK archives, MERLIN, and Terapix. We demonstrate the interoperability of these federated archives with examples using multi-wavelength image data and catalog overlays, and highlight new functionalities of the federation and integration tools.

We have used ISO to observe the Magnetic Cataclysmic Variable AE Aquarii in the previously unexplored range from 4.8 $\mu$m up to 170 $\mu$m in the framework of a coordinated multi-wavelength campaign from the radio to optical wavelengths. We have obtained for the first time a spectrum between 4.8 and 7.3 $\mu$m with ISOCAM and ISOPHOT-P: the major contribution comes from the secondary star spectrum, with some thermal emission from the accretion stream, and possibly some additional cyclotron radiation from the post-shock accretion material close to the magnetised white dwarf. Having reprocessed ISOPHOT-C data, we confirm AE Aqr detection at $90~\mu$m and we have re-estimated its upper limit at 170 $\mu$m. In addition, having re-processed IRAS data, we have detected AE Aqr at 60 $\mu$m and we have estimated its upper limits at 12, 25, and 100 $\mu$m. The literature shows that the time-averaged spectrum of AE Aqr increases roughly with frequency from the radio wavelengths up to ${\sim} 761~ \mu$m; our results indicate that it seems to be approximately flat between ~761 and ${\sim} 90 ~\mu$m, at the same level as the 3$\sigma$ upper limit at 170 $\mu$m; and it then decreases from ${\sim} 90 ~\mu$m to ${\sim} 7~ \mu$m. Thermal emission from dust grains or from a circum-binary disc seems to be very unlikely in AE Aqr, unless such a disc has properties substantially different from those predicted recently. Since various measurements and the usual assumptions on the source size suggest a brightness temperature below 109 K at $\lambda \leq 3.4$ mm, we have reconsidered also the possible mechanisms explaining the emission already known from the submillimetre to the radio. The complex average spectrum measured from ${\sim} 7~ \mu$m to the radio must be explained by emission from a plasma composed of more than one "pure" non-thermal electron energy distribution (usually assumed to be a power-law): either a very large volume (diameter $\geq$ 80 times the binary separation) could be the source of thermal bremsstrahlung which would dominate from ${\sim} 10 ~\mu$m to the ~millimetre, with, inside, a non-thermal source of synchrotron which dominates in radio; or, more probably, an initially small infrared source composed of several distributions (possibly both thermal, and non-thermal, mildly relativistic electrons) radiates gyro-synchrotron and expands moderately: it requires to be re-energised in order to lead to the observed, larger, radio source of highly relativistic electrons (in the form of several non-thermal distributions) which produce synchrotron.

We present observations of the classical nova V723 Cassiopeiae (Nova Cas 1995), obtained both with the Infrared Space Observatory (ISO) and from the ground. The infrared spectrum was dominated in the first year by H and He recombination lines, and at later times by coronal lines. The H recombination lines imply a reddening of E(B-V) = 0.78, an electron temperature of 7000 K, and an electron density of 2 × 108 cm-3 on day 250. We argue that the high-ionization species in the infrared are most likely the result of collisional ionization rather than photoionization and are therefore truly "coronal"; we estimate a temperature of 3.2 × 105 K in the coronal region and abundance ratios of S/Si 2.1, Ca/Si 1.6, and Al/Si 1.5. The ejected mass as determined from the Brα line was 2.6 × 10-5 M⊙ for a distance of 4 kpc; however, the mass deduced from the free-free emission, which we conclude arises primarily in the coronal zone, is 4.3 × 10-4 M⊙. V723 Cas did not display the [O IV] 25.89 μm fine-structure line, which was typically seen in the spectra of novae observed with ISO. There was no evidence of dust emission in V723 Cas.

Publisher Summary This chapter discusses the infrared spectroscopy of comets with Infrared Space Observatory (ISO). The ISO offers the opportunity to observe the spectrum of celestial bodies from 2.4 to 196 μm. This spectral range is of interest for the study of cometary dust. The chapter describes the IS0 observations of comets C/1995 O1 (Hale–Bopp) and 103P/Hartley 2, and discusses the nature of cometary dust. The apparition of the long-period, exceptional comet C/1995 01 (Hale–Bopp) coincided with the IS0 operation. The spectrum of this comet was observed as part of a target-of-opportunity program by an international team. The short-period comet 103P/Hartley 2 was observed in December 1997 to January 1998, close to its perihelion at 1 AU, as part of a guaranteed time program. 103P/Hartley 2 is a Jupiter-family comet that supposedly originated from the Edgeworth–Kuiper belt.

We present an atlas of near-infrared spectra (2.36m-4.1m) of300 stars at moderate resolution (/ 1500- 2000). The spectra were recorded using the Short-Wavelength Spectrometer aboard the Infrared Space Observatory (ISO-SWS). The bulk of the observations were performed during a dedicated observation campaign after the liquid helium depletion of the ISO satellite, the so-called post-helium programme. This programme was aimed at extending the MK-classification to the near- infrared. Therefore the programme covers a large range of spectral types and luminosity classes. The 2.36m-4.05 mr egion is a valuable spectral probe for both hot and cool stars. H I lines (Bracket, Pfund and Humphreys series), He I and He II lines, atomic lines and molecular lines (CO, H2O, NH, OH, SiO, HCN, C2H2, ...) are sensitive to temperature, gravity and/or the nature of the outer layers of the stellar atmosphere (outflows, hot circumstellar discs, etc.). Another objective of the programme was to construct a homogeneous dataset of near-infrared stellar spectra that can be used for population synthesis studies of galaxies. At near-infrared wavelengths these objects emit the integrated light of all stars in the system. In this paper we present the dataset of post-helium spectra completed with observations obtained during the nominal operations of the ISO-SWS. We discuss the calibration of the SWS data obtained after the liquid helium boil-o and the data reduction. We also give a first qualitative overview of how the spectral features in this wavelength range change with spectral type. The dataset is scrutinised in two papers on the quantitative classification of near-infrared spectra of early-type stars (Lenorzer et al. 2002) and late-type stars (Vandenbussche et al., in prep).

We have used ISO, the Infrared Space Observatory, to perform a systematic search for protoplanetary discs around nearby main-sequence stars. We find a strong correlation with stellar age: more than half of the stars younger than 400 Myr do have such a disc, whereas less than 10% of the older stars exhibit disc emission. Such discs seem thus to decay on a timescale of a few hundred Myr. Both the stability of the discs during this period and their decay can be explained by collisions of planetesimals. Such collisions produce the dust which is necessary to replenish the disc. The process stops as soon as the planetesimals run out, either because they are all destroyed, have escaped, or merged into planets, which implies the decay of the disc. The timescale for the dissipation of protoplanetary discs is remarkably similar to the timescale of the heavy bombardment in our Solar System. The cratering of the Moon is a clear signature of the heavy bombardment which may provide further fundamental clues to the formation of planetary systems.

We present N , 8.7 μ m, 9.8 μ m 12.5 μ m and Q bolometry of 26 stars which were observed on the IRTF. These are primarily K giants which have been well measured at other wavelengths and are chosen to be single and non-variable. Hence the data presented provides a new homogeneous set of mid IR standards. As a test of part of the calibration strategy of ISO over this wavelength range, the zero points have been set using the Kurucz model grids (1993) to predict the mid IR magnitudes from near IR data. An analysis of the errors involved is presented and a comparison with more direct methods for the determination of the zero points suggest an possible error of 0.015 mags, although the source of this error is unclear as it is at the level of the uncertainty in the more direct methods. The effect of the SiO fundamental on the spectral energy distributions of K giants is discussed.

A number of symbiotic stars have been observed with ISO. In addition to a number of emission lines, SWS observations of the symbiotic novae RR Tel and V1016 Cyg reveal prominent, broad 10 & 18 µm silicate dust features. The 10 µm, features are similar to the crystalline silicate profiles seen in classical novae. There is some evidence that the silicate brightness in V1016 Cyg varies with Mira-component phase. However, the silicate feature in RR Tel also showed some variation even though observations were made at very similar Mira-component phases. PHT observations of S-type symbiotic stars show the IR emission to be dominated by the red-giant component. However, an excess in the PHT-P filters from 10 to 15 µm is evident in all the stars, and there may be a broad 3.2 µm absorption feature or a broad 3.8 µm emission feature. At this time we have no adequate physical explanations for any of these features.

We describe the ISO programme to observe classical novae. The programme includes observations of novae during and shortly after eruption, and old novae. ISO observations of far infrared fine structure lines are providing us with information about physical conditions in nova ejecta which complement and extend knowledge obtained from ground-based observations. Surprisingly, we are getting little information about dust in nova systems, despite the fact that many novae are prolific dust-producers.