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We have mapped the edge-on galaxy NGC3628 in the 12CO(2−1) and 13CO(2−1) lines with the IRAM 30m MRT and in radio continuum at λ20 cm with the VLA. The 12CO(2−1) spectra were obtained out to a distance of 3 kpc east and 2 kpc west of the edge-on galaxy (resolution 0.4 kpc) with supplementary spectra ≃ 9 kpc east and west (1 arcmin ≃ 2 kpc at a distance of 6.7 Mpc). The resulting map shows a central peak of CO emission but also a multiple peaked structure from which we deduce a ringlike enhancement of molecular gas with a diameter of ≃ 400 pc and two outer maxima likely indicating spiral arms of the galaxy. The view of a molecular “ring” is supported by the fact that the maxima of the CO intensity are located close to the turnover radius where rigid rotation passes into differential rotation. Lesch et al. (1990) found for a number of galaxies with molecular rings that these rings can be formed by viscous accretion of molecular gas even at these radii. We find for the rigid rotating disk a molecular mass of m ≃ 108M⊙ assuming a conventional conversion factor. From our channelmaps we were able to distinguish between six unresolved clumps in the central region with comparable CO emissivity and masses of ≃ 106M⊙.
The rotation velocity of molecular gas in the halos of M82 and NGC4631 decreases with the height from the galactic plane. The slower rotation of halo gas can be explained if the gas is supplied from the central region of the galaxies due to some ejection.
1) C18O(1−0) OBSERVATIONS. We observed 13 points of C18O(1−0) (resolution 22″) around the nucleus of M82 and obtained typical main beam brightness temperatures of 20-50 mK. The intensity distribution reveals a clear double–peaked structure with the maxima seperated by 25″. The relative strength of the peaks w.r.t. the emission from the center is consistent with the presence of two point–like sources located at the peak positions. We compared our data with the 17″ CO(1−0) observations of Nakai et al. (1987) and found a strong contrast for the CO(1−0)/C18O(1−0) ratio with high values (≃30) in the center and low values (≃15) at the peak positions. This result is consistent with that of Loiseau et al. (1990) who also found with 12″ resolution for the ratios of CO(2−1)/13CO(2−1) minima at the ring locations, although not as strong as we found for the CO(1−0)/C18O(1−0) ratio. This high contrast indicates the presence of opically thick gas within the molecular ring and supports the view that the main part of the star forming process occurs in the ring.
Intense star formation activity, in the absence of interactions, occurs nearly always in barred spiral systems, but many barred galaxies do not show especially enhanced activity. On the other hand bars provide an efficient mechanism of transport of gas from the disk into the active star forming circumnuclear region (Combes and Gerin, 1987). The type of activity in the circumnuclear regions would also depend on the characteristics of the bars (Arsenault, 1989). The dynamics of the gas inside the bars could also be related to outflows of gas into the halo detected in some barred galaxies with intense nuclear activity.
We have mapped the southern galaxies NGC 613, 1313, 1433, 1566, 1672, and 2442 in the 12CO(1-0) line with the SEST telescope. The sample bases on galaxies observed previously in radio continuum at the Molonglo Observatory (Harnett, 1985).
We report multifrequency observations of the γ-ray blazar 0528+134 with the Effelsberg 100-m telescope, the IRAM 30-m telescope at Pico Veleta and the NRL Green Bank Interferometer. The observing methods are described elsewhere (Reich et al., 1993; Pohl et al., 1995). The radio lightcurves are given in Fig.1 in comparison to the status of 0528+134 in the EGRET energy range. The uncertainties in the flux densities quoted there are less than 5% at 10.55 GHz and lower frequencies, while slightly exceeding this value at 32 GHz and 86 GHz.
We have mapped the southern galaxies NGC 613, 1313, 1433, 1566, 1672 and 2442 in the 12CO(J = 1 → 0) transition with the 15-m Swedish European Submillimetre Telescope (SEST). The sample is based on galaxies previously observed in radio continuum with the Molonglo Observatory Synthesis Telescope (MOST). Strong emission is seen from the barred galaxies NGC 613 and NGC 2442 and from the active galaxies NGC 1566 and 1672. The weakest emission was from NGC 1433, while the Sd spiral NGC 1313 was not detected.
A trench-first dual damascene process has been developed for fat wires (1.26 μm pitch, 1.1 μm thickness) in a 0.18 μm CMOS process with copper/fluorosilicate glass (FSG) interconnect technology. The process window for the patterning of vias in such deep trenches depends on the trench depth and on the line width of the trench, with the worse case being an intermediate line width (lines that are 3X the via diameter). Compared to a single damascene process, the dual damascene process has comparable yield and reliability, with lower via resistance and lower cost.
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