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: http://www.stsci.edu/~kgordon/papers/2006ApJ...652.1170C.html
Дата изменения: Thu Jan 21 20:00:03 2016 Дата индексирования: Sun Apr 10 16:20:55 2016 Кодировка: Windows-1251 |
We present Spitzer imaging of the metal-deficient (Z~=30% Zsolar) Local Group dwarf galaxy NGC 6822. On spatial scales of ~130 pc, we study the nature of IR, HО+, H I, and radio continuum emission. Nebular emission strength correlates with IR surface brightness; however, roughly half of the IR emission is associated with diffuse regions not luminous at HО+ (as found in previous studies). The global ratio of dust to H I gas in the ISM, while uncertain at the factor of ~2 level, is ~25 times lower than the global values derived for spiral galaxies using similar modeling techniques; localized ratios of dust to H I gas are about a factor of 5 higher than the global value in NGC 6822. There are strong variations (factors of ~10) in the relative ratios of HО+ and IR flux throughout the central disk; the low dust content of NGC 6822 is likely responsible for the different HО+/IR ratios compared to those found in more metal-rich environments. The HО+ and IR emission is associated with high column density (>~1021 cm-2) neutral gas. Increases in IR surface brightness appear to be affected by both increased radiation field strength and increased local gas density. Individual regions and the galaxy as a whole fall within the observed scatter of recent high-resolution studies of the radio-far-IR correlation in nearby spiral galaxies; this is likely the result of depleted radio and far-IR emission strengths in the ISM of this dwarf galaxy.
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