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176 - S. Komugi , T. Tosaki , K. Kohno 2011
We present wide-field 1.1 mm continuum imaging of the nearby spiral galaxy M 33, conducted with the AzTEC bolometer camera on ASTE. We show that the 1.1 mm flux traces the distribution of dust with T ~20 K. Combined with far-infrared imaging at 160um , we derive the dust temperature distribution out to a galactic radius of ~7 kpc with a spatial resolution of ~100 parsecs. Although the 1.1 mm flux is observed predominantly near star forming regions, we find a smooth radial temperature gradient declining from ~20 K to ~13 K, consistent with recent results from the Herschel satellite. Further comparison of individual regions show a strong correlation between the cold dust temperature and the Ks band brightness, but not with the ionizing flux. The observed results imply that the dominant heating source of cold dust at few hundred parsec scales are due to the non-OB stars, even when associated with star forming regions.
214 - K. Kohno , T. Tosaki , R. Miura 2008
We present CO(3-2) emission observations toward the 3x3 (or 20x20kpc at a distance of 23Mpc) region of the southern barred spiral galaxy NGC 986 using the Atacama Submillimeter Telescope Experiment (ASTE). This effort is a part of our on-going extrag alactic CO(3-2) imaging project ADIoS (ASTE Dense gas Imaging of Spiral galaxies). Our CO(3-2) image revealed the presence of a large (the major axis is 14 kpc in total length) gaseous bar filled with dense molecular medium along the dark lanes observed in optical images. This is the largest ``dense-gas rich bar known to date. The dense gas bar discovered in NGC 986 could be a huge reservoir of possible ``fuel for future starbursts in the central region, and we suggest that the star formation in the central region of NGC 986 could still be in a growing phase. We found a good spatial coincidence between the overall distributions of dense molecular gas traced by CO(3-2) and the massive star formation depicted by H$alpha$. The global CO(3-2) luminosity $L_{rm CO(3-2)}$ of NGC 986 was determined to be $(5.4 pm 1.1) times 10^8$ K km s$^{-1}$ pc$^2$. The CO(3-2)/CO(1-0) integrated intensity ratio was found to be 0.60 +/- 0.13 at a spatial resolution of 44 or 5 kpc, and a CO(3-2)/CO(2-1) ratio was 0.67 +/- 0.14 at a beam size of ~25 or ~2.8 kpc. These line ratios suggest moderate excitation conditions of CO lines ($n_{rm H_2} sim 10^{3-4}$ cm$^{-3}$) in the central a few kpc region of NGC 986.
282 - M. Tsuboi , T. Tosaki , N. Kuno 2007
We present the results of the multi-frequency observations of radio outburst of the microquasar Cyg X-3 in February and March 2006 with the Nobeyama 45-m telescope, the Nobeyama Millimeter Array, and the Yamaguchi 32-m telescope. Since the prediction of a flare by RATAN-600, the source has been monitored from Jan 27 (UT) with these radio telescopes. At the eighteenth day after the quench of the activity, successive flares exceeding 1 Jy were observed successfully. The time scale of the variability in the active phase is presumably shorter in higher frequency bands. We also present the result of a follow-up VLBI observation at 8.4 GHz with the Japanese VLBI Network (JVN) 2.6 days after the first rise. The VLBI image exhibits a single core with a size of <8 mas (80 AU). The observed image was almost stable, although the core showed rapid variation in flux density. No jet structure was seen at a sensitivity of $T_b = 7.5times 10^5$ K.
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