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SPECTRAL EVOLUTION OF NOVAE IN THE NEAR-INFRARED BASED ON AKARI OBSERVATIONS
ITSUKI SAKON,TAKASHI ONAKA,Fumihiko Usui,SAYAKA SHIMAMOTO,RYOU OHSAWA,Takehiko Wada,Hideo Matsuhara,AKIRA ARAI 한국천문학회 2017 天文學論叢 Vol.32 No.1
We have carried out the near-infrared spectroscopic observations of recent classical novae (e.g., V2468Cyg, V1280Sco) within a few years from the outburst with AKARI as a part of AKARI Open Time Observing Program for Phase 3-II "Spectral Evolution of Novae in the Near-Infrared based on AKARI Observations (Proposal ID: SENNA)". The homogeneous datasets of near-infrared spectra from 2.5 $\mu$m to 5 $\mu$m with AKARI/IRC collected in this program are useful to infer the physical conditions of the shell formed by the ejected materials, to examine the chemical properties of the ejecta gas, and to examine the properties of dust formed in the nova ejecta.
AARON C. BELL,TAKASHI ONAKA,YASUO DOI,ITSUKI SAKON,Fumihiko Usui,DAISUKE ISHIHARA,HIDEHIRO KANEDA,MARTIN GIARD,RONIN WU,RYOU OHSAWA,TAMAMI MORI-ITO,MARK HAMMONDS,이호규,Itsuki Sakon 한국천문학회 2017 天文學論叢 Vol.32 No.1
Our understanding of dust emission, interaction, and evolution, is evolving. In recent years, electric dipole emission by spinning dust has been suggested to explain the anomalous microwave excess (AME), appearing between 10 and 90 Ghz. The observed frequencies suggest that spinning grains should be on the order of 10nm in size, hinting at polycyclic aromatic hydrocarbon molecules (PAHs). We present data from the AKARI/Infrared Camera (IRC) due to its high sensitivity to the PAH bands. By inspecting the IRC data for a few AME regions, we find a preliminary indication that regions well-fitted by a spinning-dust model have a higher 9~$\mu$m than 18~$\mu$m intensity vs. non-spinning-dust regions. Ongoing efforts to improve the analysis by using DustEM and including data from the AKARI Far Infrared Surveyor (FIS), IRAS, and Planck High Frequency Instrument (HFI) are described.
INFRARED OBSERVATIONS OF DUST AROUND HELIUM NOVA V445 PUPPIS
SAYAKA SHIMAMOTO,ITSUKI SAKON,TAKASHI ONAKA,Fumihiko Usui,TAKAFUMI OOTSUBO,YASUO DOI,RYOU OHSAWA,DAISUKE ISHIHARA 한국천문학회 2017 天文學論叢 Vol.32 No.1
We detected bright mid- to far-infrared emission from the helium nova V445 Puppis in the AKARI all-sky survey data taken in 2006. Assuming an optically thin condition, we decomposed the spectral energy distribution (SED) of V445 Puppis in October 2006 by model fitting and found that the SED can be explained by a combination of cold amorphous carbon (125~K and the mass of $4.5^{+6.6}_{-2.7}\times 10^{-4} ~{\rm M}_{\odot}$) and warm amorphous carbon (250~K and the mass of $1.8^{+1.0}_{-0.5}\times 10^{-5} ~{\rm M}_{\odot}$). Assuming that the former is pre-existing dust formed in the past nova outbursts and the latter is newly formed dust in December 2000's nova wind, this result suggests that the amount of dust formed around V445 Puppis in a single outburst is larger than $10^{-5} ~{\rm M}_{\odot}$, which is larger than those in any other classical novae ever reported.
PROCESSING OF INTERSTELLAR MEDIUM AS DIVULGED BY AKARI
TAKASHI ONAKA,TAMAMI I. MORI,RYOU OHSAWA,ITSUKI SAKON,AARON C. BELL,MARK HAMMONDS,TAKASHI SHIMONISHI,DAISUKE ISHIHARA,HIDEHIRO KANEDA,YOKO OKADA,MASAHIRO TANAKA 한국천문학회 2017 天文學論叢 Vol.32 No.1
A wide spectral coverage from near-infrared (NIR) to far-infrared (FIR) of {\it AKARI} both for imaging and spectroscopy enablesus to efficiently study the emission from gas and dust in the interstellar medium (ISM). In particular, the Infrared Camera(IRC) onboard {\it AKARI}offers a unique opportunity to carry out sensitive spectroscopy in the NIR (2--5\,$\mu$m) for the first time from a spaceborn telescope. This spectral range contains a number of important dust bands and gas lines, such as the aromatic and aliphatic emissionbands at 3.3 and 3.4--3.5\,$\mu$m, H$_2$O and CO$_2$ ices at 3.0 and 4.3\,$\mu$m, CO, H$_2$, and \ion{H}{I} gas emission lines. In this paper we concentrate on the aromatic and aliphatic emission and ice absorption features. The balance between dust supply and destruction suggests significant dust processing takingplace as well as dust formation in the ISM. Detailed analysis of the aromatic and aliphatic bands of {\it AKARI} observations for a number of\ion{H}{ii} regions and \ion{H}{ii} region-like objectssuggests processing of carbonaceous dust in the ISM. The ice formation process canalso be studied with IRC NIR spectroscopy efficiently. In this review, dust processing in the ISM divulged by recentanalysis of {\it AKARI} data is discussed.
THE DIFFUSE NEAR-INFRARED BACKGROUND SPECTRUM FROM AKARI
Tsumura Kohji,Matsumoto Toshio,Matsuura Shuji,Sakon Itsuki,Wada Takehiko 한국천문학회 2017 天文學論叢 Vol.32 No.1
We analyzed spectral data of the astrophysical diffuse emission obtained with the low-resolution spectroscopy mode on the AKARI InfraRed Camera (IRC) in the 1.8-5.3 μm wavelength region. Advanced reduction methods specialized for slit spectroscopy of diffuse sky spectra have been developed,and a catalog of 278 spectra of the diffuse sky covering a wide range of Galactic and ecliptic latitudes was constructed. Using this catalog, two other major foreground components, the zodiacal light (ZL) and the diffuse Galactic light (DGL),were separated and subtracted by taking correlations with ZL brightness estimated by the DIRBE ZL model and with the 100 μm dust thermal emission, respectively. The isotropic emission was interpreted as the extragalactic background light (EBL), which shows significant excess over the integrated light of galaxies at < 4 μm.
ICE ABSORPTION FEATURES IN NIR SPECTRA OF GALACTIC OBJECTS
TAMAMI I. MORI,TAKASHI ONAKA,ITSUKI SAKON,RYOU OHSAWA,HIDEHIRO KANEDA,MITSUYOSHI YAMAGISHI,YOKO OKADA,MASAHIRO TANAKA,TAKASHI SHIMONISHI 한국천문학회 2017 天文學論叢 Vol.32 No.1
We present results of AKARI/IRC near-infrared (NIR) slit-spectroscopy (2.5--5.0\,$\mu$m, $R \sim 100$) of Galactic sources,focusing on ice absorption features. We investigate the abundance of H$_2$O and CO$_2$ ices and other ice species (CO and XCN ices)along lines of sight towards Galactic \ion{H}{ii} regions, massive YSOs, and infrared diffuse sources. Even among those different kinds of astronomical objects,the abundance ratio of CO$_2$ to H$_2$O ices does not vary significantly,suggesting that the pathway to CO$_2$ ice formation driven by UV irradiation is not effectiveat least among the present targets.
AKARI INFRARED CAMERA SURVEY OF THE LARGE MAGELLANIC CLOUD. I. POINT-SOURCE CATALOG
Kato, Daisuke,Ita, Yoshifusa,Onaka, Takashi,Tanabé,, Toshihiko,Shimonishi, Takashi,Sakon, Itsuki,Kaneda, Hidehiro,Kawamura, Akiko,Wada, Takehiko,Usui, Fumihiko,Koo, Bon-Chul,Matsuura, Mikako,Tak American Institute of Physics 2012 The Astronomical journal Vol.144 No.6
<P>We present a near- to mid-infrared point-source catalog of five photometric bands at 3.2, 7, 11, 15, and 24 μm for a 10 deg<SUP>2</SUP> area of the Large Magellanic Cloud (LMC) obtained with the Infrared Camera on board the AKARI satellite. To cover the survey area the observations were carried out at three separate seasons from 2006 May to June, 2006 October to December, and 2007 March to July. The 10σ limiting magnitudes of the present survey are 17.9, 13.8, 12.4, 9.9, and 8.6 mag at 3.2, 7, 11, 15, and 24 μm, respectively. The photometric accuracy is estimated to be about 0.1 mag at 3.2 μm and 0.06-0.07 mag in the other bands. The position accuracy is 0<img entity='farcs' SRC='http://ej.iop.org/icons/Entities/farcs.gif' ALT='farcs' ALIGN='BOTTOM' />3 at 3.2, 7, and 11 μm and 1<img entity='farcs' SRC='http://ej.iop.org/icons/Entities/farcs.gif' ALT='farcs' ALIGN='BOTTOM' />0 at 15 and 24 μm. The sensitivities at 3.2, 7, and 24 μm are roughly comparable to those of the Spitzer SAGE LMC point-source catalog, while the AKARIcatalog provides the data at 11 and 15 μm, covering the mid-infrared spectral range contiguously. Two types of catalog are provided: a Catalog and an Archive. The Archive contains all the detected sources, while the Catalog only includes the sources that have a counterpart in the Spitzer SAGE point-source catalog. The Archive contains about 650,000, 140,000, 97,000, 43,000, and 52,000 sources at 3.2, 7, 11, 15, and 24 μm, respectively. Based on the catalog, we discuss the luminosity functions at each band, the color-color diagram, and the color-magnitude diagram using the 3.2, 7, and 11 μm band data. Stars without circumstellar envelopes, dusty C-rich and O-rich stars, young stellar objects, and background galaxies are located at distinct regions in the diagrams, suggesting that the present catalog is useful for the classification of objects toward the LMC.</P>