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تسجيل مستخدم جديدDust in the Wheel: The Cartwheel Galaxy in the Mid-IR
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We present mid-infrared images at $6.7 mu m$ and $15 mu m$ of ``The Cartwheel (AM~0035-33), the prototypical collisional ring galaxy. The observations, taken with ISOCAM, reveal the distribution of hot dust in the galaxy and its two companions in the north-east. The intensity of the mid-IR emission from the outer star forming ring of the Cartwheel shows considerable azimuthal variation and peaks at the most active H$alpha$ region of the ring. The 15 $mu m$ to 6.7 $mu m$ flux ratio of 5.2 is the highest among all the galaxies of our sample. A surprising result of our observations is the discovery of significant emission from the inner regions of the galaxy, including the inner ring, spokes and nucleus, where previously only low level H$alpha$ emission had been reported. At 6.7 $mu m$, this emission is stronger than the one from the outer star forming ring, and at 15 $mu m$, it represents 40% of the emission from the outer ring. The H$alpha$ to mid-IR flux ratios from the inner regions are consistent with the heating of grains from weak star formation activity.
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