The Tenorio Tagle scenario

Figures 42.1-42.5 present the T-T96 scenario in cartoon format.

giant H ii region giant H ii region

Figure 42.1. At time t = 0, a burst of star formation occurs and a giant H ii region forms.

Figure 42.1. At time t = 0, a burst of star formation occurs and a giant H ii region forms.

superbubble superbubble

supershell t = 1-40 Myr

Figure 42.2. During the next ~40 Myr, supernovae explode, creating a hot super-bubble confined within a large expanding supershell that bursts into the galactic halo. The superbubble contains the matter from the oxygen-rich supernova ejecta mixed with the matter from the stellar winds and with the matter thermally evaporated from the surrounding supershell.

supershell t = 1-40 Myr

Figure 42.2. During the next ~40 Myr, supernovae explode, creating a hot super-bubble confined within a large expanding supershell that bursts into the galactic halo. The superbubble contains the matter from the oxygen-rich supernova ejecta mixed with the matter from the stellar winds and with the matter thermally evaporated from the surrounding supershell.

galactic fountain with a spray galactic fountain with a spray

Figure 42.3. After the last supernova has exploded, the gas in the superbubble begins to cool down. Loci of higher densities cool down quicker. Owing to a sequence of fast repressurizing shocks, this leads to the formation of metal-rich cloudlets. The cooling timescale is of the order of 100 Myr.

Figure 42.3. After the last supernova has exploded, the gas in the superbubble begins to cool down. Loci of higher densities cool down quicker. Owing to a sequence of fast repressurizing shocks, this leads to the formation of metal-rich cloudlets. The cooling timescale is of the order of 100 Myr.

warm oxygen-rich cloudlets cold oxygen-rich cloudlets cold oxygen-rch droplets

Figure 42.4. The now-cold metal-rich cloudlets fall onto the galactic disk. They are further fragmented into metal-rich droplets by Rayleigh-Taylor instabilities. This metal-rich rain affects a region whose extent is of the order of kiloparsecs, i.e. much larger than the size of the initial H ii region.

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