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INFRARED – X-RAY CONNECTION IN NEARBY ACTIVE GALACTIC NUCLEI; AKARI AND MAXI RESULTS
Naoki Isobe,TAKAONAKAGAWA,Kenichi Yano,Shunsuke Baba,SHINKI OYABU,Yoshiki Toba,Yoshihiro Ueda,Taiki Kawamuro 한국천문학회 2017 天文學論叢 Vol.32 No.1
Combining the AKARI Point Source Catalog andthe 37-month Monitor of All-sky X-ray Image (MAXI) catalog,the infrared and X-ray properties of nearby active galactic nucleiwere investigated. The 37-month MAXI catalog tabulates 100 nearby Seyfert galaxies,73 of which are categorized into Seyfert I galaxies. Among these Seyfert galaxies,69 ones were found to have an AKARI infrared counterpart. For the Seyfert I galaxies in this sample,a well-known correlation was found between the infrared and X-ray luminosities. However, the observed X-ray luminosity of the Seyfert II galaxiestends to be lower for the infrared luminosity than the Seyfert I galaxies. This suggests thatthe X-ray absorption is significant in the Seyfert II galaxies. The Seyfert II galaxies seem to havea bimodal distribution of the IR color between $18~\mu$m and $90~\mu$m. Especially, a large fraction of the Seyfert II galaxiesexhibits a redder IR color than the Seyfert I galaxies. A possible origin of the redder IR color is briefly discussed,in relation to the star formation activity in the host galaxy,and to the X-ray absorption.
Hidenori KAI,Naoki TANI,Minoru ISOBE 한국곤충학회 2008 Entomological Research Vol.38 No.3
The significance of winter cold in the termination of diapause was investigated with regards to TIME and PIN in eggs of the silkworm Bombyx mori. TIME (time interval measuring enzyme) is an ATPase that can measure time intervals by exhibiting a transitory burst of activation of the enzyme in accordance with diapause development, which requires cold for resumption of embryonic development in the silkworm. The possible timer function of TIME comprises a built-in mechanism in the protein structure. TIME is a metallo-glycoprotein consisting of 156 amino acid residues with a unique sequence in the N-terminal region to which a sugar chain is attached. PIN (peptidyl inhibitory needle) inhibits the ATPase activity of TIME. PIN is not a simple enzyme inhibitor, but holds the timer by forming a timeregulatory complex with TIME. The carbohydrate moiety of TIME is essential for the assembly of a high-affinity PIN-binding site within the timer motif of the TIME structure. The binding interaction between TIME and PIN was much tighter (nearly 1000 times) at 25°C than that at 4°C, as measured by fluorescence polarization. Because the logEC50 at 4°C was approximately 7 nmol/L, PIN must dissociate from TIME at the physiological concentration of TIME in eggs in the winter cold. Based on the results of our study, we propose that the dissociation of the TIME–-PIN complex in the winter cold cues a series of conformational changes of TIME, ultimately reaching the active form of ATPase which in turn causes the completion of diapause development and initiates new developmental programs.
PROBING STAR FORMATION IN ULTRALUMINOUS INFRARED GALAXIES USING AKARI NEAR-INFRARED SPECTROSCOPY
Kenichi Yano,TAKAO NAKAGAWA,Naoki Isobe,MAI SHIRAHATA 한국천문학회 2017 天文學論叢 Vol.32 No.1
We performed systematic observations of the \ion{H}{i} Br$\alpha$ line (4.05 $\mu$m)in 51 nearby (z<0.3) ultraluminous infrared galaxies(ULIRGs), using AKARI near-infrared spectroscopy. The Br$\alpha$ line is predicted to be the brightest among the \ion{H}{i} recombination linesin ULIRGs with visual extinction higher than 15 mag. We detected the Br$\alpha$ line in 33 ULIRGs. In these galaxies, the relative contribution ofstarburst to the total infrared luminosity ($L_\mathrm{IR}$)is estimated on the basis of the ratio ofthe Br$\alpha$ line luminosity ($L_{\mathrm{Br}\alpha}$) to $L_\mathrm{IR}$. The mean $L_{\mathrm{Br}\alpha}/L_\mathrm{IR}$ ratioin LINERs or Seyfertsis significantly lower (~ 50%)than that in \ion{H}{ii} galaxies. This result indicates that active galactic nuclei contributesignificantly (~ 50%) to $L_\mathrm{IR}$ in LINERs,as well as Seyferts. We also estimate the absolutecontribution of starburst to $L_\mathrm{IR}$ using the ratio of star formation rates (SFRs)derived from $L_{\mathrm{Br}\alpha}$ (SFR$_{\mathrm{Br}\alpha}$) and those neededto explain $L_\mathrm{IR}$ (SFR$_\mathrm{IR}$). The mean SFR$_{\mathrm{Br}\alpha}/$SFR$_\mathrm{IR}$ratio is only 0.33 even in\ion{H}{ii} galaxies,where starburst is supposed to dominate the luminosity. We attribute this apparently low SFR$_{\mathrm{Br}\alpha}/$SFR$_\mathrm{IR}$ratio to the absorption ofionizing photons by dust within \ion{H}{ii} regions.
STUDY OF SPECTRAL ENERGY DISTRIBUTION OF GALAXIES WITH PRINCIPAL COMPONENT ANALYSIS
Chihiro Kochi,TAKAO NAKAGAWA,Naoki Isobe,MAI SHIRAHATA,Kenichi Yano,Shunsuke Baba 한국천문학회 2017 天文學論叢 Vol.32 No.1
We performed Principle Component Analysis\,(PCA) over 264 galaxies in the {\it IRAS} Revised Bright Galaxy \blue{Sample \citep{Sanders2003}} using 12, 25, 60 and 100\,$\mu$m flux data observed by {\it IRAS} and 9, 18, 65, 90 and 140\,$\mu$m flux data observed by {\it AKARI}. We \blue{found} that (i)the first principle component \blue{was} largely contributed by infrared to visible flux ratio, (ii)the second principal component \blue{was} largely contributed by the flux ratio between {\it IRAS} and {\it AKARI}, (iii)the third principle component \blue{was} largely contributed by infrared colors.
DEVELOPMENT OF NEW STITCHING INTERFEROMETRY FOR THE SPICA TELESCOPE
Asa Yamanaka,HIDEHIRO KANEDA,MITSUYOSHI YAMAGISHI,TORU KONDO,Takuma Kokusho,Kotomi Tanaka,Misaki Hanaoka,TAKAO NAKAGAWA,Mitsunobu Kawada,Naoki Isobe,Toshiaki Arai,TAKASHI ONAKA 한국천문학회 2017 天文學論叢 Vol.32 No.1
The telescope to be onboard SPICA (Space Infrared Telescope for Cosmology and Astrophysics) has an aperture diameter of 2.5 m and its imaging performance is to be diffraction-limited at a wavelength of 20 μm at the operating temperature of < 8 K. Because manufacturing precise autocollimating flat mirrors (ACFs) with sizes comparable to the SPICA telescope is not technically feasible, we plan to use sub-aperture stitching interferometry through ACFs for optical testing of the telescope. We have verified the applicability of the sub-aperture stitching technique to the SPICA telescope by performing stitching experiments in a vacuum at a room temperature, using the 800-mm telescope and a 300-mm ACF. We have also developed a new method to reduce uncertainties possibly caused by cryogenic and gravitational deformations of ACFs.
Probing the precise location of the radio core in the TeV blazar Mrk 501 with VERA at 43 GHz
Koyama, Shoko,Kino, Motoki,Doi, Akihiro,Niinuma, Kotaro,Hada, Kazuhiro,Nagai, Hiroshi,Honma, Mareki,Akiyama, Kazunori,Giroletti, Marcello,Giovannini, Gabriele,Orienti, Monica,Isobe, Naoki,Kataoka, Jun Astronomical Society of Japan 2015 Publications of the Astronomical Society of Japan Vol.67 No.4