First Light is a book about how the first stars formed, and how they're quite different from our sun and the stars being formed today. I read it on a plane and it was relatively light and didn't keep me from napping when I needed to.
The earliest stars were formed when most of the universe was either Hydrogen or Helium. By definition there weren't other elements since those had yet to have been forged in the hearts of stars.What I enjoyed about this book is that it takes pains to reveal mysteries that we still don't understand:
It wasn’t until the 1930s that it was realised that this absorption line was not due to a new element at all, but was instead a different form of the already familiar element, iron. Iron usually has 26 electrons and is associated with a well-known set of absorption lines. If we take away some of those electrons (we ionise the iron), then those absorption lines change. The absorption line linked to the mythical element coronium was identical to the absorption line produced by an iron atom that has had 13 electrons removed. Removing electrons is no easy job and requires very high temperatures to create high-energy collisions capable of dislodging electrons. To remove 13 electrons requires blisteringly high temperatures, indicating that the corona is millions of degrees Kelvin compared to the comparatively chilly 5,800K photosphere. So the Sun does indeed get hotter as you venture into the corona, an entirely unintuitive situation. Perhaps the high temperatures are produced by complicated magnetic fields violently throwing charged particles up from the photosphere into the corona, or perhaps bomb-like explosions called nano-flares throw heat up into the atmosphere. The theories are being narrowed down, but the Coronal Heating Problem remains an unsolved quandary. * * * It might disappoint you that I haven’t been able to tie up the Coronal Heating Problem in a neat and satisfying way. It’s annoying not knowing the answer, isn’t it? And surprising considering the resources we command. We have built probes that have travelled all the way into interstellar space, and Hubble can see well outside the Milky Way to a multitude of other galaxies. We understand how our Universe evolved, even right back to having a solid theory for its creation, the Big Bang. Yet we still race to exploit every bit of scientific understanding we can from seven minutes of totality, just as scientists were doing in 1925, albeit now with more advanced technology. We add to our knowledge in one sense (the corona isn’t made of an unusual element – it’s just really hot!), then add to our questions in another (wait, how is it that hot?!). I will admit that the Coronal Heating Problem was fairly new to me at the time of the Great American Eclipse. As an astrophysicist studying the first stars, it hadn’t ever occurred to me to pay much attention to the nearest star – the mundane, predictable Sun. (kindle loc 406)
The book describes how it's taken years and they've still not discovered a generation 1 star (one that has a very low percentage of non hydrogen/helium). That's because those very old stars were mostly very big and hence had a short lifespan. In addition, to look for those old stars you have to look back in time a long way,
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