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THE AKARI PROJECT: LEGACY AND DATA PROCESSING STATUS
TAKAO NAKAGAWA,ISSEI YAMAMURA 한국천문학회 2017 天文學論叢 Vol.32 No.1
This paper provides an overview of the AKARI mission,which was the first Japanese satellitededicated to infrared astronomy. The \textit{AKARI} satellite was launched in 2006, and performed both an all-sky survey and pointedobservations during its 550 days in the He-cooled mission phases (Phases 1 and 2). After the He ranout, we continued near-infrared observations with mechanical cryocoolers (Phase 3). Due to a failureof its power supply, AKARI was turned off in 2011.
HIGHLY EXCITED CO LINES IN ACTIVE GALAXIES BOTH IN ABSORPTION AND IN EMISSION
TAKAO NAKAGAWA,Mai Shirahata,Tomonori Usuda 한국천문학회 2017 天文學論叢 Vol.32 No.1
In order to reveal physical conditions of molecular gas in active galaxies(“active galaxies” mean both starbursts and AGNs in this paper),we carried out systematic observations(R = 19 ~ 120) of CO fundamental band at 4.7 $\mu$m in absorption with\textit{AKARI}. We also made follow-upCO absorption observations at higher spectral resolution (R = 5000 ~ 1000) with \textit{Subaru}. Recently, \textit{Herschel}made extensive observations of highly-excited CO lines in emission in the far-infrared. The two datasets (absorption and emission) sometimes provide us with apparently inconsistent results. One case is starburst galaxies:\textit{Subaru} observations showed low temperature of molecular gas toward the starburstNGC253, while \textit{Herschel} detected highly excited CO lines in the starburst. This suggests that warmmolecular clouds are more deeply embedded than newly formed star clusters. The other case is obscured AGNs;\textit{Herschel} detected highly excited CO lines in emission in nearby AGNs,while \textit{AKARI} and\textit{Subaru} observations showed CO absorptiononly in some of the obscured AGNs. This could reflect the difference of nature of molecular tori in these AGNs. We propose the combination of the absorption and emission observationsas an effective tool to reveal geometry of warm molecular clouds in activegalaxies.
THE NEXT-GENERATION INFRARED SPACE MISSION SPICA: PROJECT UPDATES
TAKAO NAKAGAWA,Hiroshi Shibai,HIDEHIRO KANEDA,Kotaro Kohno,Hideo Matsuhara,Hiroyuki Ogawa,TAKASHI ONAKA,Peter Roelfsema,Toru Yamada 한국천문학회 2017 天文學論叢 Vol.32 No.1
We present project updates of the next-generationinfrared space mission SPICA (Space Infrared Telescope for Cosmology and Astrophysics)as of November 2015. SPICA isoptimized for mid- and far-infrared astronomy with unprecedented sensitivity, which will be achievedwith a cryogenically cooled (below 8 K), large (2.5~m) telescope. SPICA is expected to address a number ofkey questions in various fields of astrophysics, ranging from studies of the star-formation history in theuniverse to the formation and evolution of planetary systems. The international collaboration framework of SPICA has been revisited. SPICA under the new framework passed the Mission Definition Review by JAXA in 2015. A proposal under the new framework to ESA is being prepared. The target launch year in the new framework is 2027/28.
THE NEXT-GENERATION INFRARED ASTRONOMY MISSION SPICA UNDER THE NEW FRAMEWORK
NAKAGAWA, TAKAO,SHIBAI, HIROSHI,ONAKA, TAKASHI,MATSUHARA, HIDEO,KANEDA, HIDEHIRO,KAWAKATSU, YASUHIRO The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2
We present the current status (as of August 2014) of SPICA (Space Infrared Telescope for Cosmology and Astrophysics), which is a mission optimized for mid- and far-infrared astronomy with a cryogenically cooled 3m-class telescope. SPICA is expected to achieve high spatial resolution and unprecedented sensitivity in the mid- and far-infrared, which will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. We have carried out the "Risk Mitigation Phase" activity, in which key technologies essential to the realization of the mission have been extensively developed. Consequently, technical risks for the success of the mission have been significantly mitigated. Along with these technical activities, the international collaboration framework of SPICA has been revisited, which resulted in la arger contribution from ESA than that in the original plan. To enable the ESA participation under the new framework, a SPICA proposal to ESA is under consideration as a medium-class mission under the framework of the ESA Cosmic Vision. The target launch year of SPICA under the new framework is the mid-2020s.
First Near-infrared Imaging Polarimetry of Young Stellar Objects in the Circinus Molecular Cloud
Kwon, Jungmi,Nakagawa, Takao,Tamura, Motohide,Hough, James H.,Choi, Minho,Kandori, Ryo,Nagata, Tetsuya,Kang, Miju Published by the University of Chicago Press for t 2018 The Astrophysical journal Supplement series Vol.234 No.2
<P>We present the results of near-infrared (NIR) linear imaging polarimetry in the J, H, and K-s bands of the low-mass star cluster-forming region in the Circinus Molecular Cloud Complex. Using aperture polarimetry of point-like sources, positive detection of 314, 421, and 164 sources in the J, H, and Ks bands, respectively, was determined from among 749 sources whose photometric magnitudes were measured. For the source classification of the 133 point-like sources whose polarization could be measured in all 3 bands, a color-color diagram was used. While most of the NIR polarizations of point-like sources are well-aligned and can be explained by dichroic polarization produced by aligned interstellar dust grains in the cloud, 123 highly polarized sources have also been identified with some criteria. The projected direction on the sky of the magnetic field in the Cir-MMS region is indicated by the mean polarization position angles (70 degrees) of the point-like sources in the observed region, corresponding to approximately 1.6 x 1.6 pc(2). In addition, the magnetic field direction is compared with the outflow orientations associated with Infrared Astronomy Satellite sources, in which two sources were found to be aligned with each other and one source was not. We also show prominent polarization nebulosities over the Cir-MMS region for the first time. Our polarization data have revealed one clear infrared reflection nebula (IRN) and several candidate IRNe in the Cir-MMS field. In addition, the illuminating sources of the IRNe are identified with near-and mid-infrared sources.</P>
AN EXTENSION OF A RELIABLE WAVELENGTH COVERAGE OF THE AKARI NG GRISM MODE
Shunsuke Baba,TAKAO NAKAGAWA,NAIKI ISOBE,MAI SHIRAHATA,YOUICHI OHYAMA,KENICHI YANO,CHIHIRO KOCHI 한국천문학회 2017 天文學論叢 Vol.32 No.1
The Infrared Camera onboard the \textit{AKARI} satellite carried out spectroscopic observations with a grism mode named \textit{NG}, whose wavelength coverage was 2.5--5.0~$\mu$m. We reinvestigate the current flux calibration for the \textit{NG} grism mode, with which calculated flux density implausibly decreases at 4.9~$\mu$m especially for red objects due to the second-order light contamination. We perform a new spectral response calibration using blue and red standard objects simultaneously. New response curves which contain both the first- and second-order light are able to separate each contribution consistently and useful for studies of red objects such as CO ro-vibrational absorption in active galactic nuclei.