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Дата изменения: Unknown Дата индексирования: Tue Oct 2 15:15:48 2012 Кодировка: Поисковые слова: внешние планеты |
Your main research interests concern galactic structure.
The study of high redshift galaxies has become enormously trendy in recent years. Researchers are flooding into the field from all directions, gobbling up vast amounts of telescope time, and now are asking for yet more money to build some huge and expensive facilities to indulge their hobby.
You find this all rather premature. Sure: if we understood galaxies in the local universe well, it might be time to go out and study more distant ones. But, as it happens, we really don't know very much even about our very own galaxy, the Milky Way! How can we possibly hope to understand some little smudge in the corner of a CCD frame, a high redshift galaxy, when we have so little idea about what is going on right here?
Surely, if you want to investigate what happened 10 billion years ago, one sensible way is to look at what that period produced: ie. galaxies like our own. This has been the tried and tested way of studying galaxy formation, and has led to most of the current theories. For example, the division of stars in our galaxy into dynamically and chemically different populations (the thin and thick disks, halo and bulge) is surely telling us something crucial about how our galaxy formed. A good example is the famous G-dwarf problem: even the oldest, lowest metallicity stars in our galaxy are not that metal poor. Somehow, the cloud that formed our galaxy must have already been metal enriched. How did this happen? There must presumably have been some primordial, pre-galactic population of stars that did the enrichment and then disappeared.
By looking at the different stellar populations, we could determine when different bits of gas arrived in our galaxy, and what types of stars they formed. The dynamics of the different populations and their metalicities and abundances tell us how and where they formed. We are never going to be able to learn this much about galaxy formation by looking at some smudge at the edge of the universe.